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philperry9
Joined: 23 Nov 2011
Posts: 381
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 Posted: Thu Feb 25, 2016 7:50 am Post subject: Control Stick Slop - Bushings |
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Also, by putting the motion on the bolt, any future replacement of parts from wear would involve a new bushing and potentially new bolt. Cheap and easy to replace.
Putting be motion on the welded piece would lead to a new bushing and potentially new weldment. Expensive and more complex to repair.
Phil
Sent from my iPhone
On Feb 25, 2016, at 9:45 AM, Phillip Perry <philperry9(at)gmail.com (philperry9(at)gmail.com)> wrote:
| Quote: | You want the pivot point on the bolt and not the steel welded part. That welded part isn't perfectly round (oblong) from the heat and it's also rough, abrasive, and susceptible to rust - contributing for abrasion and wear.
If you keep the motion on the bolt, you have a perfectly round and smooth pivot point. The nut is pinned so there's no chance of running the nut off.
Phil
Sent from my iPhone
On Feb 25, 2016, at 9:10 AM, Carl Froehlich <carl.froehlich(at)verizon.net (carl.froehlich(at)verizon.net)> wrote:
| Quote: | v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} <![endif]--> <![endif]--> <![endif]-->
”I tuned this part of the system like you would a wheel bearing. I rotated the sticks left and right while tightening the nut one flat at a time. Once I began to feel tension on the sticks, I stopped and backed off one flat where I then dropped in the cotter key in to lock it into position.”
Perhaps I’m reading this wrong. I thought the objective was for the bolt to capture the bushing so that there is no relative motion between the bolt and the bushing. All relative motion should be between the outside of the bushing and the weldment (in this case the Control Stick Base Pivot Tube).
I also believe adding a light grease for the bushing to weldment provides for reduced corrosion between the dissimilar metals – obviously not an issue when using delrin but perhaps would help keep dirt out of the bearing surface.
Carl
From: owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com) [mailto:owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com)] On Behalf Of Phillip Perry
Sent: Thursday, February 25, 2016 12:53 AM
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Subject: Re: RV10-List: Re: Control Stick Slop - Bushings
I thought I'd follow up on the control stick slop issue that I had in my system since I promised a post-bushing report. I had some major play in my control sticks and ended up following Sean's advice and replaced the brass bushings with delrin. I attached a couple of photos of the plans to help with the explanation.
After discovering the slop, I ordered delrin rods from Aircraft Spruce. I ordered 3/8" hoping they'd be a drop-in replacement for a tight fit without any machining and 7/16" in case I had to machine them down to something closer to proper size for a good fit in the control stick base. Each stick was about $3 for a 3 ft stick, so there was no harm in ordering both.
I pulled the sticks, stick bases, and control column out of the plane and put it on the bench. On disassembly, I found that there was play between the brass bushing and the welded part of the stick bases. I tried the 3/8" rod to see how well it fit and it dropped straight through unrestricted. The inside of the welded stick bases were way more than the spec'd 3/8". That was one part of the problem. The other part of the problem was the slop on the inside of the bushing between the bushing and the 1/4" bolt. That slop was worse than the welded part. Additionally I found one more location for slop and that was the ability to slide the stick forward and aft on the 1/4" bolt between the stick bases and the control column that the stick bases mount to.
The first order of business was to get new bushings machined out. Since the stick bases were more than 3/8" I used the 7/16" delrin rod and turned it down on a lathe that another guy on the airport had. It was turned down until it was a thumb-press fit into the stick bases.
The next step was to drill and ream the hole for the 1/4" bolt down the center. I initially tried to ream it to 15/64 (1/64" undersized for the 1/4" bolt) to get a snug fit in the event that the bolt was on the skinny side of the tolerance. That didn't work out and I ultimately had to open it to a full 1/4" to get the bolt to slide through.
Back to the work bench where I installed the new bushings. The fit was free of any play between that bases and the bushing and between the bushing and the bolt.
The final task was to eliminate the sliding motion of the sticks forward and aft on the 1/4" bolt between the stick bases and the control column. This was a pretty simple task of inserting AN960-416 and 416L washers to shim as much of the gaps away as possible. Obviously you can't get all of the gap out, so you have to take care of the last little bit by tightening the nut and pulling the control column in tighter on the stick bases.
I tuned this part of the system like you would a wheel bearing. I rotated the sticks left and right while tightening the nut one flat at a time. Once I began to feel tension on the sticks, I stopped and backed off one flat where I then dropped in the cotter key in to lock it into position.
The system linkages are tight (meaning no play) and very smooth (minus the drag of the TruTrak servos). You can work the left and right sticks in opposition directions, like driving a bull dozer, and you won't find any play. You can go all the way out to the control surface and hold it tight while wiggling the stick and not find any play between the control surface and stick. I'm very happy with the outcome.
This wasn't a terrible change to make and if you have the seats out and access to a lathe, you could probably do it in less than a day. You certainly could do it on a drill press with some forethought. creative jigs, patience, and a few sacrificed pieces of delrin while you traverse the learning curve, but the lathe is certainly the fastest and easiest.
I'd do it again... Glad it turned out the way it did.
Phil
<image001.png>
<image002.png>
On Sat, Feb 13, 2016 at 8:08 PM, Phillip Perry <philperry9(at)gmail.com (philperry9(at)gmail.com)> wrote:
I have some delrin coming and I'm planning on making them for my sloppiness.
I'm planning on reaming the bell crank to 3/8 and then seeing how well a 3/8 delrin rod fits. If it's still too loose, I have a 7/16 rod coming in the mail too. I'll be able turn it down to fit or possibly it would fit without any working (though I doubt it).
Once I find the rod that fits best, then I'll ream the center on a friends lathe. I have a 3/16" reamer that will work, but I plan on using another reamer that's 11/64 (1/64 under sized) to see how it fits first. Then if it's too tight I'll open it up to the full 3/16 with the other reamer.
I'll probably have a report on how well it works in the next 2 weeks or possibly late next week.
Phil
Sent from my iPhone
h --
EE Gifts!)
on
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ion" rel="noreferrer" target="_blank">http://www.matronics.com/contribution
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ion" rel="noreferrer" target="_blank">http://www.matronics.com/contribution
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Tim Olson
Joined: 25 Jan 2007
Posts: 2872
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| Posted: Thu Feb 25, 2016 8:20 am Post subject: Control Stick Slop - Bushings |
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Phil beat me to it. You're absolutely right.
(I like yours and Seans solution by the way)
The housing on the outside of the bushing isn't
really round, so you wouldn't want it to rotate on the
bushing there. If it DID wear, it could potentially wear
a larger hole in the housing, which would then be harder
to fix later. If you rotate it on the bolt, a simple
change of bolt and you're back to normal specs. The
Delrin should work real well.
This whole mess happened on mine, and I used a filler to
surround the bushing and basically "epoxy" it in to the
weldment. That way it can only rotate on the bolt.
And I took up the end slop as well...also out in the
aileron bellcranks. You should look at those areas and
think about where wear is going to happen, and try to
ensure that any surface that will wear, is a replaceable
part. You will find there are a few places that can
be improved upon from the plans...just like the
original nose gear axle...that was a horrible design
until they went with thicker spacer...then it was just
a bad design. The Matco axle is a great improvement.
Tim
On 2/25/2016 9:50 AM, Phillip Perry wrote:
| Quote: | Also, by putting the motion on the bolt, any future replacement of parts
from wear would involve a new bushing and potentially new bolt. Cheap
and easy to replace.
Putting be motion on the welded piece would lead to a new bushing and
potentially new weldment. Expensive and more complex to repair.
Phil
Sent from my iPhone
On Feb 25, 2016, at 9:45 AM, Phillip Perry <philperry9(at)gmail.com
<mailto:philperry9(at)gmail.com>> wrote:
> You want the pivot point on the bolt and not the steel welded part.
> That welded part isn't perfectly round (oblong) from the heat and
> it's also rough, abrasive, and susceptible to rust - contributing for
> abrasion and wear.
>
> If you keep the motion on the bolt, you have a perfectly round and
> smooth pivot point. The nut is pinned so there's no chance of running
> the nut off.
>
> PhilI'm very happy with the
>> outcome.
>>
>> This wasn't a terrible change to make and if you have the seats out
>> and access to a lathe, you could probably do it in less than a day.
>> You certainly could do it on a drill press with some forethought.
>> creative jigs, patience, and a few sacrificed pieces of delrin while
>> you traverse the learning curve, but the lathe is certainly the
>> fastest and easiest.
>>
>> I'd do it again... Glad it turned out the way it did.
>>
>> Phil
>>
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carl.froehlich(at)verizon
Guest
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| Posted: Thu Feb 25, 2016 8:28 am Post subject: Control Stick Slop - Bushings |
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Thanks Phil – but I’ll have to disagree.
Relative motion between the bushing and bolt means you have small bearing surfaces, and a nice hard steel bolt wearing steel mating surfaces (the bolt holes in the weldment). The function of the bushing is to provide a large bearing surface (between the bushing and the pivot tube). The larger surface area contributes to why we enjoy such smooth controls in our RVs. The same principle applies to bell cranks and rod end bearings – no relative motion around the bolt.
There is need from time to time to shorten either the pivot tube or bushing to achieve slop free operation. You rare cases you may also find need to ream out the pivot tube. The bushing, when firmly captured in the weldment, should have perhaps 1/32” exposed on each side of the pivot tube. If needed washers are added to make sure the weldment is not deformed when the bolt is tightened – thus maintaining this small gap and preventing binding. Again a little grease between the bushing and pivot tube is recommended.
Carl
From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Phillip Perry
Sent: Thursday, February 25, 2016 10:50 AM
To: rv10-list(at)matronics.com
Subject: Re: Re: Control Stick Slop - Bushings
Also, by putting the motion on the bolt, any future replacement of parts from wear would involve a new bushing and potentially new bolt. Cheap and easy to replace.
Putting be motion on the welded piece would lead to a new bushing and potentially new weldment. Expensive and more complex to repair.
Phil
Sent from my iPhone
On Feb 25, 2016, at 9:45 AM, Phillip Perry <philperry9(at)gmail.com (philperry9(at)gmail.com)> wrote:
| Quote: |
You want the pivot point on the bolt and not the steel welded part. That welded part isn't perfectly round (oblong) from the heat and it's also rough, abrasive, and susceptible to rust - contributing for abrasion and wear.
If you keep the motion on the bolt, you have a perfectly round and smooth pivot point. The nut is pinned so there's no chance of running the nut off.
Phil
Sent from my iPhone
On Feb 25, 2016, at 9:10 AM, Carl Froehlich <carl.froehlich(at)verizon.net (carl.froehlich(at)verizon.net)> wrote:
| Quote: |
”I tuned this part of the system like you would a wheel bearing. I rotated the sticks left and right while tightening the nut one flat at a time. Once I began to feel tension on the sticks, I stopped and backed off one flat where I then dropped in the cotter key in to lock it into position.”
Perhaps I’m reading this wrong. I thought the objective was for the bolt to capture the bushing so that there is no relative motion between the bolt and the bushing. All relative motion should be between the outside of the bushing and the weldment (in this case the Control Stick Base Pivot Tube).
I also believe adding a light grease for the bushing to weldment provides for reduced corrosion between the dissimilar metals – obviously not an issue when using delrin but perhaps would help keep dirt out of the bearing surface.
Carl
From: owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com) [mailto:owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com)] On Behalf Of Phillip Perry
Sent: Thursday, February 25, 2016 12:53 AM
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Subject: Re: Re: Control Stick Slop - Bushings
I thought I'd follow up on the control stick slop issue that I had in my system since I promised a post-bushing report. I had some major play in my control sticks and ended up following Sean's advice and replaced the brass bushings with delrin. I attached a couple of photos of the plans to help with the explanation.
After discovering the slop, I ordered delrin rods from Aircraft Spruce. I ordered 3/8" hoping they'd be a drop-in replacement for a tight fit without any machining and 7/16" in case I had to machine them down to something closer to proper size for a good fit in the control stick base. Each stick was about $3 for a 3 ft stick, so there was no harm in ordering both.
I pulled the sticks, stick bases, and control column out of the plane and put it on the bench. On disassembly, I found that there was play between the brass bushing and the welded part of the stick bases. I tried the 3/8" rod to see how well it fit and it dropped straight through unrestricted. The inside of the welded stick bases were way more than the spec'd 3/8". That was one part of the problem. The other part of the problem was the slop on the inside of the bushing between the bushing and the 1/4" bolt. That slop was worse than the welded part. Additionally I found one more location for slop and that was the ability to slide the stick forward and aft on the 1/4" bolt between the stick bases and the control column that the stick bases mount to.
The first order of business was to get new bushings machined out. Since the stick bases were more than 3/8" I used the 7/16" delrin rod and turned it down on a lathe that another guy on the airport had. It was turned down until it was a thumb-press fit into the stick bases.
The next step was to drill and ream the hole for the 1/4" bolt down the center. I initially tried to ream it to 15/64 (1/64" undersized for the 1/4" bolt) to get a snug fit in the event that the bolt was on the skinny side of the tolerance. That didn't work out and I ultimately had to open it to a full 1/4" to get the bolt to slide through.
Back to the work bench where I installed the new bushings. The fit was free of any play between that bases and the bushing and between the bushing and the bolt.
The final task was to eliminate the sliding motion of the sticks forward and aft on the 1/4" bolt between the stick bases and the control column. This was a pretty simple task of inserting AN960-416 and 416L washers to shim as much of the gaps away as possible. Obviously you can't get all of the gap out, so you have to take care of the last little bit by tightening the nut and pulling the control column in tighter on the stick bases.
I tuned this part of the system like you would a wheel bearing. I rotated the sticks left and right while tightening the nut one flat at a time. Once I began to feel tension on the sticks, I stopped and backed off one flat where I then dropped in the cotter key in to lock it into position.
The system linkages are tight (meaning no play) and very smooth (minus the drag of the TruTrak servos). You can work the left and right sticks in opposition directions, like driving a bull dozer, and you won't find any play. You can go all the way out to the control surface and hold it tight while wiggling the stick and not find any play between the control surface and stick. I'm very happy with the outcome.
This wasn't a terrible change to make and if you have the seats out and access to a lathe, you could probably do it in less than a day. You certainly could do it on a drill press with some forethought. creative jigs, patience, and a few sacrificed pieces of delrin while you traverse the learning curve, but the lathe is certainly the fastest and easiest.
I'd do it again... Glad it turned out the way it did.
Phil
<image001.png>
<image002.png>
On Sat, Feb 13, 2016 at 8:08 PM, Phillip Perry <philperry9(at)gmail.com (philperry9(at)gmail.com)> wrote:
I have some delrin coming and I'm planning on making them for my sloppiness.
I'm planning on reaming the bell crank to 3/8 and then seeing how well a 3/8 delrin rod fits. If it's still too loose, I have a 7/16 rod coming in the mail too. I'll be able turn it down to fit or possibly it would fit without any working (though I doubt it).
Once I find the rod that fits best, then I'll ream the center on a friends lathe. I have a 3/16" reamer that will work, but I plan on using another reamer that's 11/64 (1/64 under sized) to see how it fits first. Then if it's too tight I'll open it up to the full 3/16 with the other reamer.
I'll probably have a report on how well it works in the next 2 weeks or possibly late next week.
Phil
Sent from my iPhone
h --
EE Gifts!)
on
r> ed
://www.buildersbooks.com" rel="noreferrer" target="_blank">www.buildersbooks.com
ion" rel="noreferrer" target="_blank">http://www.matronics.com/contribution
-Matt Dralle, List Admin.
=============
br> ?RV10-List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?RV10-List
=============
S WEB FORUMS -
="noreferrer" target="_blank">http://forums.matronics.com
=============
on Web Site -
-Matt Dralle, List Admin.
ion" rel="noreferrer" target="_blank">http://www.matronics.com/contribution
=============
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http://www.matronics.com/Navigator?RV10-List |
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philperry9
Joined: 23 Nov 2011
Posts: 381
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| Posted: Thu Feb 25, 2016 8:36 am Post subject: Control Stick Slop - Bushings |
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I thought about JB welding my bushing to the weldment or Lok-Tite. Both would have helped significantly reduce the play. But I had so much slop on the inside of the bushing that it still would have been notable.
If you don't have that much slop on the inside of the bushing, Tim's solution to permanently place the bushing inside he weldment could work really well for you.
Phil
Sent from my iPhone
| Quote: | On Feb 25, 2016, at 10:19 AM, Tim Olson <Tim(at)MyRV10.com> wrote:
Phil beat me to it. You're absolutely right.
(I like yours and Seans solution by the way)
The housing on the outside of the bushing isn't
really round, so you wouldn't want it to rotate on the
bushing there. If it DID wear, it could potentially wear
a larger hole in the housing, which would then be harder
to fix later. If you rotate it on the bolt, a simple
change of bolt and you're back to normal specs. The
Delrin should work real well.
This whole mess happened on mine, and I used a filler to
surround the bushing and basically "epoxy" it in to the
weldment. That way it can only rotate on the bolt.
And I took up the end slop as well...also out in the
aileron bellcranks. You should look at those areas and
think about where wear is going to happen, and try to
ensure that any surface that will wear, is a replaceable
part. You will find there are a few places that can
be improved upon from the plans...just like the
original nose gear axle...that was a horrible design
until they went with thicker spacer...then it was just
a bad design. The Matco axle is a great improvement.
Tim
> On 2/25/2016 9:50 AM, Phillip Perry wrote:
> Also, by putting the motion on the bolt, any future replacement of parts
> from wear would involve a new bushing and potentially new bolt. Cheap
> and easy to replace.
>
> Putting be motion on the welded piece would lead to a new bushing and
> potentially new weldment. Expensive and more complex to repair.
>
> Phil
>
>
>
> Sent from my iPhone
>
> On Feb 25, 2016, at 9:45 AM, Phillip Perry <philperry9(at)gmail.com
> <mailto:philperry9(at)gmail.com>> wrote:
>
>> You want the pivot point on the bolt and not the steel welded part.
>> That welded part isn't perfectly round (oblong) from the heat and
>> it's also rough, abrasive, and susceptible to rust - contributing for
>> abrasion and wear.
>>
>> If you keep the motion on the bolt, you have a perfectly round and
>> smooth pivot point. The nut is pinned so there's no chance of running
>> the nut off.
>>
>> PhilI'm very happy with the
>>> outcome.
>>>
>>> This wasn't a terrible change to make and if you have the seats out
>>> and access to a lathe, you could probably do it in less than a day.
>>> You certainly could do it on a drill press with some forethought.
>>> creative jigs, patience, and a few sacrificed pieces of delrin while
>>> you traverse the learning curve, but the lathe is certainly the
>>> fastest and easiest.
>>>
>>> I'd do it again... Glad it turned out the way it did.
>>>
>>> Phil
|
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Tim Olson
Joined: 25 Jan 2007
Posts: 2872
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| Posted: Thu Feb 25, 2016 8:47 am Post subject: Control Stick Slop - Bushings |
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|
Yeah, except I think Delrin is a better solution for the long
term. Cheap, and easy to replace.
I did see Carl's reply about the outer surface being required
to be the pivot point for smooth control operation, but I
just have to totally disagree. The controls when pivoting
on the bolt are very very smooth. And when you get the play
out of the system it's just sweet. My sticks flop around
easily with no effort. And, if the bolt does start to wear,
it will be easy to detect because the slop will come back.
In either the case of the Delrin, or the brass/bronze,
I think it'll be a long long time to wait to worry
about it. I lube mine occasionally but I'm up to over
1100 hours and have found no slop yet. I'll be surprised
if the bolt doesn't last 2000+ hours.
Tim
On 2/25/2016 10:34 AM, Phillip Perry wrote:
| Quote: |
<philperry9(at)gmail.com>
I thought about JB welding my bushing to the weldment or Lok-Tite.
Both would have helped significantly reduce the play. But I had so
much slop on the inside of the bushing that it still would have been
notable.
If you don't have that much slop on the inside of the bushing, Tim's
solution to permanently place the bushing inside he weldment could
work really well for you.
Phil
Sent from my iPhone
> On Feb 25, 2016, at 10:19 AM, Tim Olson <Tim(at)MyRV10.com> wrote:
>
>
>
> Phil beat me to it. You're absolutely right. (I like yours and
> Seans solution by the way) The housing on the outside of the
> bushing isn't really round, so you wouldn't want it to rotate on
> the bushing there. If it DID wear, it could potentially wear a
> larger hole in the housing, which would then be harder to fix
> later. If you rotate it on the bolt, a simple change of bolt and
> you're back to normal specs. The Delrin should work real well.
>
> This whole mess happened on mine, and I used a filler to surround
> the bushing and basically "epoxy" it in to the weldment. That way
> it can only rotate on the bolt. And I took up the end slop as
> well...also out in the aileron bellcranks. You should look at
> those areas and think about where wear is going to happen, and try
> to ensure that any surface that will wear, is a replaceable part.
> You will find there are a few places that can be improved upon from
> the plans...just like the original nose gear axle...that was a
> horrible design until they went with thicker spacer...then it was
> just a bad design. The Matco axle is a great improvement. Tim
|
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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philperry9
Joined: 23 Nov 2011
Posts: 381
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| Posted: Thu Feb 25, 2016 8:54 am Post subject: Control Stick Slop - Bushings |
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|
As Tim said, according to the plans you're right.
But after digging into the problem in more detail and understanding the issues with the inconsistent weldment and poor fit of the bushing, I believe the plans are the worst possible solution and can be improved on.
Will the plans work? Yes, for most people. But in my case I had tolerance stacking with multiple loose surfaces compounding into a more significant and noticeable problem.
Now the controls have zero slop and are silky smooth and consistent through full movement in all directions.
There's no doubt that the modification to the plans improved the control system in my plane greatly.
Phil
Sent from my iPhone
On Feb 25, 2016, at 10:28 AM, Carl Froehlich <carl.froehlich(at)verizon.net (carl.froehlich(at)verizon.net)> wrote:
| Quote: | <![endif]--> <![endif]-->
Thanks Phil – but I’ll have to disagree.
Relative motion between the bushing and bolt means you have small bearing surfaces, and a nice hard steel bolt wearing steel mating surfaces (the bolt holes in the weldment). The function of the bushing is to provide a large bearing surface (between the bushing and the pivot tube). The larger surface area contributes to why we enjoy such smooth controls in our RVs. The same principle applies to bell cranks and rod end bearings – no relative motion around the bolt.
There is need from time to time to shorten either the pivot tube or bushing to achieve slop free operation. You rare cases you may also find need to ream out the pivot tube. The bushing, when firmly captured in the weldment, should have perhaps 1/32” exposed on each side of the pivot tube. If needed washers are added to make sure the weldment is not deformed when the bolt is tightened – thus maintaining this small gap and preventing binding. Again a little grease between the bushing and pivot tube is recommended.
Carl
From: owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com) [mailto:owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com)] On Behalf Of Phillip Perry
Sent: Thursday, February 25, 2016 10:50 AM
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Subject: Re: Re: Control Stick Slop - Bushings
Also, by putting the motion on the bolt, any future replacement of parts from wear would involve a new bushing and potentially new bolt. Cheap and easy to replace.
Putting be motion on the welded piece would lead to a new bushing and potentially new weldment. Expensive and more complex to repair.
Phil
Sent from my iPhone
On Feb 25, 2016, at 9:45 AM, Phillip Perry <philperry9(at)gmail.com (philperry9(at)gmail.com)> wrote:
| Quote: |
You want the pivot point on the bolt and not the steel welded part. That welded part isn't perfectly round (oblong) from the heat and it's also rough, abrasive, and susceptible to rust - contributing for abrasion and wear.
If you keep the motion on the bolt, you have a perfectly round and smooth pivot point. The nut is pinned so there's no chance of running the nut off.
Phil
Sent from my iPhone
On Feb 25, 2016, at 9:10 AM, Carl Froehlich <carl.froehlich(at)verizon.net (carl.froehlich(at)verizon.net)> wrote:
| Quote: |
”I tuned this part of the system like you would a wheel bearing. I rotated the sticks left and right while tightening the nut one flat at a time. Once I began to feel tension on the sticks, I stopped and backed off one flat where I then dropped in the cotter key in to lock it into position.”
Perhaps I’m reading this wrong. I thought the objective was for the bolt to capture the bushing so that there is no relative motion between the bolt and the bushing. All relative motion should be between the outside of the bushing and the weldment (in this case the Control Stick Base Pivot Tube).
I also believe adding a light grease for the bushing to weldment provides for reduced corrosion between the dissimilar metals – obviously not an issue when using delrin but perhaps would help keep dirt out of the bearing surface.
Carl
From: owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com) [mailto:owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com)] On Behalf Of Phillip Perry
Sent: Thursday, February 25, 2016 12:53 AM
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Subject: Re: Re: Control Stick Slop - Bushings
I thought I'd follow up on the control stick slop issue that I had in my system since I promised a post-bushing report. I had some major play in my control sticks and ended up following Sean's advice and replaced the brass bushings with delrin. I attached a couple of photos of the plans to help with the explanation.
After discovering the slop, I ordered delrin rods from Aircraft Spruce. I ordered 3/8" hoping they'd be a drop-in replacement for a tight fit without any machining and 7/16" in case I had to machine them down to something closer to proper size for a good fit in the control stick base. Each stick was about $3 for a 3 ft stick, so there was no harm in ordering both.
I pulled the sticks, stick bases, and control column out of the plane and put it on the bench. On disassembly, I found that there was play between the brass bushing and the welded part of the stick bases. I tried the 3/8" rod to see how well it fit and it dropped straight through unrestricted. The inside of the welded stick bases were way more than the spec'd 3/8". That was one part of the problem. The other part of the problem was the slop on the inside of the bushing between the bushing and the 1/4" bolt. That slop was worse than the welded part. Additionally I found one more location for slop and that was the ability to slide the stick forward and aft on the 1/4" bolt between the stick bases and the control column that the stick bases mount to.
The first order of business was to get new bushings machined out. Since the stick bases were more than 3/8" I used the 7/16" delrin rod and turned it down on a lathe that another guy on the airport had. It was turned down until it was a thumb-press fit into the stick bases.
The next step was to drill and ream the hole for the 1/4" bolt down the center. I initially tried to ream it to 15/64 (1/64" undersized for the 1/4" bolt) to get a snug fit in the event that the bolt was on the skinny side of the tolerance. That didn't work out and I ultimately had to open it to a full 1/4" to get the bolt to slide through.
Back to the work bench where I installed the new bushings. The fit was free of any play between that bases and the bushing and between the bushing and the bolt.
The final task was to eliminate the sliding motion of the sticks forward and aft on the 1/4" bolt between the stick bases and the control column. This was a pretty simple task of inserting AN960-416 and 416L washers to shim as much of the gaps away as possible. Obviously you can't get all of the gap out, so you have to take care of the last little bit by tightening the nut and pulling the control column in tighter on the stick bases.
I tuned this part of the system like you would a wheel bearing. I rotated the sticks left and right while tightening the nut one flat at a time. Once I began to feel tension on the sticks, I stopped and backed off one flat where I then dropped in the cotter key in to lock it into position.
The system linkages are tight (meaning no play) and very smooth (minus the drag of the TruTrak servos). You can work the left and right sticks in opposition directions, like driving a bull dozer, and you won't find any play. You can go all the way out to the control surface and hold it tight while wiggling the stick and not find any play between the control surface and stick. I'm very happy with the outcome.
This wasn't a terrible change to make and if you have the seats out and access to a lathe, you could probably do it in less than a day. You certainly could do it on a drill press with some forethought. creative jigs, patience, and a few sacrificed pieces of delrin while you traverse the learning curve, but the lathe is certainly the fastest and easiest.
I'd do it again... Glad it turned out the way it did.
Phil
<image001.png>
<image002.png>
On Sat, Feb 13, 2016 at 8:08 PM, Phillip Perry <philperry9(at)gmail.com (philperry9(at)gmail.com)> wrote:
I have some delrin coming and I'm planning on making them for my sloppiness.
I'm planning on reaming the bell crank to 3/8 and then seeing how well a 3/8 delrin rod fits. If it's still too loose, I have a 7/16 rod coming in the mail too. I'll be able turn it down to fit or possibly it would fit without any working (though I doubt it).
Once I find the rod that fits best, then I'll ream the center on a friends lathe. I have a 3/16" reamer that will work, but I plan on using another reamer that's 11/64 (1/64 under sized) to see how it fits first. Then if it's too tight I'll open it up to the full 3/16 with the other reamer.
I'll probably have a report on how well it works in the next 2 weeks or possibly late next week.
Phil
Sent from my iPhone
h --
EE Gifts!)
on
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ion" rel="noreferrer" target="_blank">http://www.matronics.com/contribution
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carl.froehlich(at)verizon
Guest
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| Posted: Thu Feb 25, 2016 9:25 am Post subject: Control Stick Slop - Bushings |
|
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Ok Phil & Tim.
For those reading however I want to emphasize you have transformed a large surface area soft brass bushing (the wear element) in a steel tube bearing to a “knife edge” bearing with a steel bolt riding on the small steel weldment bolt hole tabs. It will work, but for most I offer careful assembly of these bearings, bell cranks and such per plans would be the best option. For both of my planes I too enjoy smooth, no slop controls.
Now going back into the woodwork…..
Carl
From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Phillip Perry
Sent: Thursday, February 25, 2016 11:54 AM
To: rv10-list(at)matronics.com
Subject: Re: Re: Control Stick Slop - Bushings
As Tim said, according to the plans you're right.
But after digging into the problem in more detail and understanding the issues with the inconsistent weldment and poor fit of the bushing, I believe the plans are the worst possible solution and can be improved on.
Will the plans work? Yes, for most people. But in my case I had tolerance stacking with multiple loose surfaces compounding into a more significant and noticeable problem.
Now the controls have zero slop and are silky smooth and consistent through full movement in all directions.
There's no doubt that the modification to the plans improved the control system in my plane greatly.
Phil
Sent from my iPhone
On Feb 25, 2016, at 10:28 AM, Carl Froehlich <carl.froehlich(at)verizon.net (carl.froehlich(at)verizon.net)> wrote:
| Quote: |
Thanks Phil – but I’ll have to disagree.
Relative motion between the bushing and bolt means you have small bearing surfaces, and a nice hard steel bolt wearing steel mating surfaces (the bolt holes in the weldment). The function of the bushing is to provide a large bearing surface (between the bushing and the pivot tube). The larger surface area contributes to why we enjoy such smooth controls in our RVs. The same principle applies to bell cranks and rod end bearings – no relative motion around the bolt.
There is need from time to time to shorten either the pivot tube or bushing to achieve slop free operation. You rare cases you may also find need to ream out the pivot tube. The bushing, when firmly captured in the weldment, should have perhaps 1/32” exposed on each side of the pivot tube. If needed washers are added to make sure the weldment is not deformed when the bolt is tightened – thus maintaining this small gap and preventing binding. Again a little grease between the bushing and pivot tube is recommended.
Carl
From: owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com) [mailto:owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com)] On Behalf Of Phillip Perry
Sent: Thursday, February 25, 2016 10:50 AM
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Subject: Re: Re: Control Stick Slop - Bushings
Also, by putting the motion on the bolt, any future replacement of parts from wear would involve a new bushing and potentially new bolt. Cheap and easy to replace.
Putting be motion on the welded piece would lead to a new bushing and potentially new weldment. Expensive and more complex to repair.
Phil
Sent from my iPhone
On Feb 25, 2016, at 9:45 AM, Phillip Perry <philperry9(at)gmail.com (philperry9(at)gmail.com)> wrote:
| Quote: |
You want the pivot point on the bolt and not the steel welded part. That welded part isn't perfectly round (oblong) from the heat and it's also rough, abrasive, and susceptible to rust - contributing for abrasion and wear.
If you keep the motion on the bolt, you have a perfectly round and smooth pivot point. The nut is pinned so there's no chance of running the nut off.
Phil
Sent from my iPhone
On Feb 25, 2016, at 9:10 AM, Carl Froehlich <carl.froehlich(at)verizon.net (carl.froehlich(at)verizon.net)> wrote:
| Quote: |
”I tuned this part of the system like you would a wheel bearing. I rotated the sticks left and right while tightening the nut one flat at a time. Once I began to feel tension on the sticks, I stopped and backed off one flat where I then dropped in the cotter key in to lock it into position.”
Perhaps I’m reading this wrong. I thought the objective was for the bolt to capture the bushing so that there is no relative motion between the bolt and the bushing. All relative motion should be between the outside of the bushing and the weldment (in this case the Control Stick Base Pivot Tube).
I also believe adding a light grease for the bushing to weldment provides for reduced corrosion between the dissimilar metals – obviously not an issue when using delrin but perhaps would help keep dirt out of the bearing surface.
Carl
From: owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com) [mailto:owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com)] On Behalf Of Phillip Perry
Sent: Thursday, February 25, 2016 12:53 AM
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Subject: Re: Re: Control Stick Slop - Bushings
I thought I'd follow up on the control stick slop issue that I had in my system since I promised a post-bushing report. I had some major play in my control sticks and ended up following Sean's advice and replaced the brass bushings with delrin. I attached a couple of photos of the plans to help with the explanation.
After discovering the slop, I ordered delrin rods from Aircraft Spruce. I ordered 3/8" hoping they'd be a drop-in replacement for a tight fit without any machining and 7/16" in case I had to machine them down to something closer to proper size for a good fit in the control stick base. Each stick was about $3 for a 3 ft stick, so there was no harm in ordering both.
I pulled the sticks, stick bases, and control column out of the plane and put it on the bench. On disassembly, I found that there was play between the brass bushing and the welded part of the stick bases. I tried the 3/8" rod to see how well it fit and it dropped straight through unrestricted. The inside of the welded stick bases were way more than the spec'd 3/8". That was one part of the problem. The other part of the problem was the slop on the inside of the bushing between the bushing and the 1/4" bolt. That slop was worse than the welded part. Additionally I found one more location for slop and that was the ability to slide the stick forward and aft on the 1/4" bolt between the stick bases and the control column that the stick bases mount to.
The first order of business was to get new bushings machined out. Since the stick bases were more than 3/8" I used the 7/16" delrin rod and turned it down on a lathe that another guy on the airport had. It was turned down until it was a thumb-press fit into the stick bases.
The next step was to drill and ream the hole for the 1/4" bolt down the center. I initially tried to ream it to 15/64 (1/64" undersized for the 1/4" bolt) to get a snug fit in the event that the bolt was on the skinny side of the tolerance. That didn't work out and I ultimately had to open it to a full 1/4" to get the bolt to slide through.
Back to the work bench where I installed the new bushings. The fit was free of any play between that bases and the bushing and between the bushing and the bolt.
The final task was to eliminate the sliding motion of the sticks forward and aft on the 1/4" bolt between the stick bases and the control column. This was a pretty simple task of inserting AN960-416 and 416L washers to shim as much of the gaps away as possible. Obviously you can't get all of the gap out, so you have to take care of the last little bit by tightening the nut and pulling the control column in tighter on the stick bases.
I tuned this part of the system like you would a wheel bearing. I rotated the sticks left and right while tightening the nut one flat at a time. Once I began to feel tension on the sticks, I stopped and backed off one flat where I then dropped in the cotter key in to lock it into position.
The system linkages are tight (meaning no play) and very smooth (minus the drag of the TruTrak servos). You can work the left and right sticks in opposition directions, like driving a bull dozer, and you won't find any play. You can go all the way out to the control surface and hold it tight while wiggling the stick and not find any play between the control surface and stick. I'm very happy with the outcome.
This wasn't a terrible change to make and if you have the seats out and access to a lathe, you could probably do it in less than a day. You certainly could do it on a drill press with some forethought. creative jigs, patience, and a few sacrificed pieces of delrin while you traverse the learning curve, but the lathe is certainly the fastest and easiest.
I'd do it again... Glad it turned out the way it did.
Phil
<image001.png>
<image002.png>
On Sat, Feb 13, 2016 at 8:08 PM, Phillip Perry <philperry9(at)gmail.com (philperry9(at)gmail.com)> wrote:
I have some delrin coming and I'm planning on making them for my sloppiness.
I'm planning on reaming the bell crank to 3/8 and then seeing how well a 3/8 delrin rod fits. If it's still too loose, I have a 7/16 rod coming in the mail too. I'll be able turn it down to fit or possibly it would fit without any working (though I doubt it).
Once I find the rod that fits best, then I'll ream the center on a friends lathe. I have a 3/16" reamer that will work, but I plan on using another reamer that's 11/64 (1/64 under sized) to see how it fits first. Then if it's too tight I'll open it up to the full 3/16 with the other reamer.
I'll probably have a report on how well it works in the next 2 weeks or possibly late next week.
Phil
Sent from my iPhone
h --
EE Gifts!)
on
r> ed
://www.buildersbooks.com" rel="noreferrer" target="_blank">www.buildersbooks.com
ion" rel="noreferrer" target="_blank">http://www.matronics.com/contribution
-Matt Dralle, List Admin.
=============
br> ?RV10-List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?RV10-List
=============
S WEB FORUMS -
="noreferrer" target="_blank">http://forums.matronics.com
=============
on Web Site -
-Matt Dralle, List Admin.
ion" rel="noreferrer" target="_blank">http://www.matronics.com/contribution
=============
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Tim Olson
Joined: 25 Jan 2007
Posts: 2872
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| Posted: Thu Feb 25, 2016 9:45 am Post subject: Control Stick Slop - Bushings |
|
|
I think if they REALLY wanted it to be that way, the way
the weldment is produced is very poor. They should have a
machined hole through the weldment, not that bent metal
seam where the parts come together. It would need to be
made with much more precision. If nothing else, a
different solution would be to glue in a stainless or
steel sleeve of some sort, that is thinner, to provide a
nice consistent bore. Then the bushing could be sized to
fit and it would be more precise. But the weldment isn't
a precision bore of any sort.
And so, as we talked about, you consider the long term wear
implications, it's just much easier for long term maintenance
to make the bolt (and bushing) be the easily replaceable items.
And, while I haven't tried this, it certainly would be possible
to use a larger diameter bolt and bore out the delrin bushing,
if you want to use a thicker bolt...but I see no point in that.
Tim
On 2/25/2016 10:54 AM, Phillip Perry wrote:
| Quote: | As Tim said, according to the plans you're right.
But after digging into the problem in more detail and understanding the
issues with the inconsistent weldment and poor fit of the bushing, I
believe the plans are the worst possible solution and can be improved on.
Will the plans work? Yes, for most people. But in my case I had
tolerance stacking with multiple loose surfaces compounding into a more
significant and noticeable problem.
Now the controls have zero slop and are silky smooth and consistent
through full movement in all directions.
There's no doubt that the modification to the plans improved the control
system in my plane greatly.
Phil
|
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http://www.matronics.com/Navigator?RV10-List |
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philperry9
Joined: 23 Nov 2011
Posts: 381
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| Posted: Thu Feb 25, 2016 9:50 am Post subject: Control Stick Slop - Bushings |
|
|
I understand what you're saying now. You're worried about he bolt rotating on the steel weldment and having a knife edge wear point. That makes sense.
However, I should point out that the bolt is not rotating at all. Just like the plans.
Because the bolt doesn't rotate, all of the rotation occurs inside the bushing. The wear surface is the smooth interface between the bolt and the bushing and not the bolt and the weldment edges. That would be a mistake as you could saw the bolt right in two and it would be inconsistent too.
The case you're describing isn't an issue.
Here's a video I just shot showing where the rotation occurs.
http://youtu.be/SaywmrHZW24
Phil
Sent from my iPhone
On Feb 25, 2016, at 11:24 AM, Carl Froehlich <carl.froehlich(at)verizon.net (carl.froehlich(at)verizon.net)> wrote:
| Quote: | <![endif]--> <![endif]-->
Ok Phil & Tim.
For those reading however I want to emphasize you have transformed a large surface area soft brass bushing (the wear element) in a steel tube bearing to a “knife edge” bearing with a steel bolt riding on the small steel weldment bolt hole tabs. It will work, but for most I offer careful assembly of these bearings, bell cranks and such per plans would be the best option. For both of my planes I too enjoy smooth, no slop controls.
Now going back into the woodwork…..
Carl
From: owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com) [mailto:owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com)] On Behalf Of Phillip Perry
Sent: Thursday, February 25, 2016 11:54 AM
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Subject: Re: Re: Control Stick Slop - Bushings
As Tim said, according to the plans you're right.
But after digging into the problem in more detail and understanding the issues with the inconsistent weldment and poor fit of the bushing, I believe the plans are the worst possible solution and can be improved on.
Will the plans work? Yes, for most people. But in my case I had tolerance stacking with multiple loose surfaces compounding into a more significant and noticeable problem.
Now the controls have zero slop and are silky smooth and consistent through full movement in all directions.
There's no doubt that the modification to the plans improved the control system in my plane greatly.
Phil
Sent from my iPhone
On Feb 25, 2016, at 10:28 AM, Carl Froehlich <carl.froehlich(at)verizon.net (carl.froehlich(at)verizon.net)> wrote:
| Quote: |
Thanks Phil – but I’ll have to disagree.
Relative motion between the bushing and bolt means you have small bearing surfaces, and a nice hard steel bolt wearing steel mating surfaces (the bolt holes in the weldment). The function of the bushing is to provide a large bearing surface (between the bushing and the pivot tube). The larger surface area contributes to why we enjoy such smooth controls in our RVs. The same principle applies to bell cranks and rod end bearings – no relative motion around the bolt.
There is need from time to time to shorten either the pivot tube or bushing to achieve slop free operation. You rare cases you may also find need to ream out the pivot tube. The bushing, when firmly captured in the weldment, should have perhaps 1/32” exposed on each side of the pivot tube. If needed washers are added to make sure the weldment is not deformed when the bolt is tightened – thus maintaining this small gap and preventing binding. Again a little grease between the bushing and pivot tube is recommended.
Carl
From: owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com) [mailto:owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com)] On Behalf Of Phillip Perry
Sent: Thursday, February 25, 2016 10:50 AM
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Subject: Re: Re: Control Stick Slop - Bushings
Also, by putting the motion on the bolt, any future replacement of parts from wear would involve a new bushing and potentially new bolt. Cheap and easy to replace.
Putting be motion on the welded piece would lead to a new bushing and potentially new weldment. Expensive and more complex to repair.
Phil
Sent from my iPhone
On Feb 25, 2016, at 9:45 AM, Phillip Perry <philperry9(at)gmail.com (philperry9(at)gmail.com)> wrote:
| Quote: |
You want the pivot point on the bolt and not the steel welded part. That welded part isn't perfectly round (oblong) from the heat and it's also rough, abrasive, and susceptible to rust - contributing for abrasion and wear.
If you keep the motion on the bolt, you have a perfectly round and smooth pivot point. The nut is pinned so there's no chance of running the nut off.
Phil
Sent from my iPhone
On Feb 25, 2016, at 9:10 AM, Carl Froehlich <carl.froehlich(at)verizon.net (carl.froehlich(at)verizon.net)> wrote:
| Quote: |
”I tuned this part of the system like you would a wheel bearing. I rotated the sticks left and right while tightening the nut one flat at a time. Once I began to feel tension on the sticks, I stopped and backed off one flat where I then dropped in the cotter key in to lock it into position.”
Perhaps I’m reading this wrong. I thought the objective was for the bolt to capture the bushing so that there is no relative motion between the bolt and the bushing. All relative motion should be between the outside of the bushing and the weldment (in this case the Control Stick Base Pivot Tube).
I also believe adding a light grease for the bushing to weldment provides for reduced corrosion between the dissimilar metals – obviously not an issue when using delrin but perhaps would help keep dirt out of the bearing surface.
Carl
From: owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com) [mailto:owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com)] On Behalf Of Phillip Perry
Sent: Thursday, February 25, 2016 12:53 AM
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Subject: Re: Re: Control Stick Slop - Bushings
I thought I'd follow up on the control stick slop issue that I had in my system since I promised a post-bushing report. I had some major play in my control sticks and ended up following Sean's advice and replaced the brass bushings with delrin. I attached a couple of photos of the plans to help with the explanation.
After discovering the slop, I ordered delrin rods from Aircraft Spruce. I ordered 3/8" hoping they'd be a drop-in replacement for a tight fit without any machining and 7/16" in case I had to machine them down to something closer to proper size for a good fit in the control stick base. Each stick was about $3 for a 3 ft stick, so there was no harm in ordering both.
I pulled the sticks, stick bases, and control column out of the plane and put it on the bench. On disassembly, I found that there was play between the brass bushing and the welded part of the stick bases. I tried the 3/8" rod to see how well it fit and it dropped straight through unrestricted. The inside of the welded stick bases were way more than the spec'd 3/8". That was one part of the problem. The other part of the problem was the slop on the inside of the bushing between the bushing and the 1/4" bolt. That slop was worse than the welded part. Additionally I found one more location for slop and that was the ability to slide the stick forward and aft on the 1/4" bolt between the stick bases and the control column that the stick bases mount to.
The first order of business was to get new bushings machined out. Since the stick bases were more than 3/8" I used the 7/16" delrin rod and turned it down on a lathe that another guy on the airport had. It was turned down until it was a thumb-press fit into the stick bases.
The next step was to drill and ream the hole for the 1/4" bolt down the center. I initially tried to ream it to 15/64 (1/64" undersized for the 1/4" bolt) to get a snug fit in the event that the bolt was on the skinny side of the tolerance. That didn't work out and I ultimately had to open it to a full 1/4" to get the bolt to slide through.
Back to the work bench where I installed the new bushings. The fit was free of any play between that bases and the bushing and between the bushing and the bolt.
The final task was to eliminate the sliding motion of the sticks forward and aft on the 1/4" bolt between the stick bases and the control column. This was a pretty simple task of inserting AN960-416 and 416L washers to shim as much of the gaps away as possible. Obviously you can't get all of the gap out, so you have to take care of the last little bit by tightening the nut and pulling the control column in tighter on the stick bases.
I tuned this part of the system like you would a wheel bearing. I rotated the sticks left and right while tightening the nut one flat at a time. Once I began to feel tension on the sticks, I stopped and backed off one flat where I then dropped in the cotter key in to lock it into position.
The system linkages are tight (meaning no play) and very smooth (minus the drag of the TruTrak servos). You can work the left and right sticks in opposition directions, like driving a bull dozer, and you won't find any play. You can go all the way out to the control surface and hold it tight while wiggling the stick and not find any play between the control surface and stick. I'm very happy with the outcome.
This wasn't a terrible change to make and if you have the seats out and access to a lathe, you could probably do it in less than a day. You certainly could do it on a drill press with some forethought. creative jigs, patience, and a few sacrificed pieces of delrin while you traverse the learning curve, but the lathe is certainly the fastest and easiest.
I'd do it again... Glad it turned out the way it did.
Phil
<image001.png>
<image002.png>
On Sat, Feb 13, 2016 at 8:08 PM, Phillip Perry <philperry9(at)gmail.com (philperry9(at)gmail.com)> wrote:
I have some delrin coming and I'm planning on making them for my sloppiness.
I'm planning on reaming the bell crank to 3/8 and then seeing how well a 3/8 delrin rod fits. If it's still too loose, I have a 7/16 rod coming in the mail too. I'll be able turn it down to fit or possibly it would fit without any working (though I doubt it).
Once I find the rod that fits best, then I'll ream the center on a friends lathe. I have a 3/16" reamer that will work, but I plan on using another reamer that's 11/64 (1/64 under sized) to see how it fits first. Then if it's too tight I'll open it up to the full 3/16 with the other reamer.
I'll probably have a report on how well it works in the next 2 weeks or possibly late next week.
Phil
Sent from my iPhone
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carl.froehlich(at)verizon
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| Posted: Thu Feb 25, 2016 11:14 am Post subject: Control Stick Slop - Bushings |
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Ok – again thanks Phil for the explanation, but you pulled me back out of the woodwork.
You now have the soft delrin rubbing against the steel tabs on the weldment. The fact that you have no rotation between the bolt and the steel weldment tabs is by your careful application of torque on the nut. The delrin rotates around the bolt only because you have, right now, more friction between the bolt head and nut and the weldment tabs than you do between the delrin ends and the weldment tabs. Perhaps this stays the same but I’d be surprised if the delrin rod end wear does not open up the joint – leaving the bolt loose and free to rotate in the tabs and end up as I described.
I assume the reason why you did not simply make the delrin as a replacement for the brass bushing is that you did not like the inside of the steel bearing tube. You would have a much larger bearing surface area between the delrin and the steel bearing tube, and a much larger wear area. Perhaps you got a bad one. I’ve seen some that needed to be reamed to size but none that where so bad not to use.
But – we all get to build the planes as we want. I have also deviated from the plans when I did not like a particular design element.
Carl
From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Phillip Perry
Sent: Thursday, February 25, 2016 12:50 PM
To: rv10-list(at)matronics.com
Subject: Re: Re: Control Stick Slop - Bushings
I understand what you're saying now. You're worried about he bolt rotating on the steel weldment and having a knife edge wear point. That makes sense.
However, I should point out that the bolt is not rotating at all. Just like the plans.
Because the bolt doesn't rotate, all of the rotation occurs inside the bushing. The wear surface is the smooth interface between the bolt and the bushing and not the bolt and the weldment edges. That would be a mistake as you could saw the bolt right in two and it would be inconsistent too.
The case you're describing isn't an issue.
Here's a video I just shot showing where the rotation occurs.
http://youtu.be/SaywmrHZW24
Phil
Sent from my iPhone
On Feb 25, 2016, at 11:24 AM, Carl Froehlich <carl.froehlich(at)verizon.net (carl.froehlich(at)verizon.net)> wrote:
| Quote: |
Ok Phil & Tim.
For those reading however I want to emphasize you have transformed a large surface area soft brass bushing (the wear element) in a steel tube bearing to a “knife edge” bearing with a steel bolt riding on the small steel weldment bolt hole tabs. It will work, but for most I offer careful assembly of these bearings, bell cranks and such per plans would be the best option. For both of my planes I too enjoy smooth, no slop controls.
Now going back into the woodwork…..
Carl
From: owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com) [mailto:owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com)] On Behalf Of Phillip Perry
Sent: Thursday, February 25, 2016 11:54 AM
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Subject: Re: Re: Control Stick Slop - Bushings
As Tim said, according to the plans you're right.
But after digging into the problem in more detail and understanding the issues with the inconsistent weldment and poor fit of the bushing, I believe the plans are the worst possible solution and can be improved on.
Will the plans work? Yes, for most people. But in my case I had tolerance stacking with multiple loose surfaces compounding into a more significant and noticeable problem.
Now the controls have zero slop and are silky smooth and consistent through full movement in all directions.
There's no doubt that the modification to the plans improved the control system in my plane greatly.
Phil
Sent from my iPhone
On Feb 25, 2016, at 10:28 AM, Carl Froehlich <carl.froehlich(at)verizon.net (carl.froehlich(at)verizon.net)> wrote:
| Quote: |
Thanks Phil – but I’ll have to disagree.
Relative motion between the bushing and bolt means you have small bearing surfaces, and a nice hard steel bolt wearing steel mating surfaces (the bolt holes in the weldment). The function of the bushing is to provide a large bearing surface (between the bushing and the pivot tube). The larger surface area contributes to why we enjoy such smooth controls in our RVs. The same principle applies to bell cranks and rod end bearings – no relative motion around the bolt.
There is need from time to time to shorten either the pivot tube or bushing to achieve slop free operation. You rare cases you may also find need to ream out the pivot tube. The bushing, when firmly captured in the weldment, should have perhaps 1/32” exposed on each side of the pivot tube. If needed washers are added to make sure the weldment is not deformed when the bolt is tightened – thus maintaining this small gap and preventing binding. Again a little grease between the bushing and pivot tube is recommended.
Carl
From: owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com) [mailto:owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com)] On Behalf Of Phillip Perry
Sent: Thursday, February 25, 2016 10:50 AM
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Subject: Re: Re: Control Stick Slop - Bushings
Also, by putting the motion on the bolt, any future replacement of parts from wear would involve a new bushing and potentially new bolt. Cheap and easy to replace.
Putting be motion on the welded piece would lead to a new bushing and potentially new weldment. Expensive and more complex to repair.
Phil
Sent from my iPhone
On Feb 25, 2016, at 9:45 AM, Phillip Perry <philperry9(at)gmail.com (philperry9(at)gmail.com)> wrote:
| Quote: |
You want the pivot point on the bolt and not the steel welded part. That welded part isn't perfectly round (oblong) from the heat and it's also rough, abrasive, and susceptible to rust - contributing for abrasion and wear.
If you keep the motion on the bolt, you have a perfectly round and smooth pivot point. The nut is pinned so there's no chance of running the nut off.
Phil
Sent from my iPhone
On Feb 25, 2016, at 9:10 AM, Carl Froehlich <carl.froehlich(at)verizon.net (carl.froehlich(at)verizon.net)> wrote:
| Quote: |
”I tuned this part of the system like you would a wheel bearing. I rotated the sticks left and right while tightening the nut one flat at a time. Once I began to feel tension on the sticks, I stopped and backed off one flat where I then dropped in the cotter key in to lock it into position.”
Perhaps I’m reading this wrong. I thought the objective was for the bolt to capture the bushing so that there is no relative motion between the bolt and the bushing. All relative motion should be between the outside of the bushing and the weldment (in this case the Control Stick Base Pivot Tube).
I also believe adding a light grease for the bushing to weldment provides for reduced corrosion between the dissimilar metals – obviously not an issue when using delrin but perhaps would help keep dirt out of the bearing surface.
Carl
From: owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com) [mailto:owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com)] On Behalf Of Phillip Perry
Sent: Thursday, February 25, 2016 12:53 AM
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Subject: Re: Re: Control Stick Slop - Bushings
I thought I'd follow up on the control stick slop issue that I had in my system since I promised a post-bushing report. I had some major play in my control sticks and ended up following Sean's advice and replaced the brass bushings with delrin. I attached a couple of photos of the plans to help with the explanation.
After discovering the slop, I ordered delrin rods from Aircraft Spruce. I ordered 3/8" hoping they'd be a drop-in replacement for a tight fit without any machining and 7/16" in case I had to machine them down to something closer to proper size for a good fit in the control stick base. Each stick was about $3 for a 3 ft stick, so there was no harm in ordering both.
I pulled the sticks, stick bases, and control column out of the plane and put it on the bench. On disassembly, I found that there was play between the brass bushing and the welded part of the stick bases. I tried the 3/8" rod to see how well it fit and it dropped straight through unrestricted. The inside of the welded stick bases were way more than the spec'd 3/8". That was one part of the problem. The other part of the problem was the slop on the inside of the bushing between the bushing and the 1/4" bolt. That slop was worse than the welded part. Additionally I found one more location for slop and that was the ability to slide the stick forward and aft on the 1/4" bolt between the stick bases and the control column that the stick bases mount to.
The first order of business was to get new bushings machined out. Since the stick bases were more than 3/8" I used the 7/16" delrin rod and turned it down on a lathe that another guy on the airport had. It was turned down until it was a thumb-press fit into the stick bases.
The next step was to drill and ream the hole for the 1/4" bolt down the center. I initially tried to ream it to 15/64 (1/64" undersized for the 1/4" bolt) to get a snug fit in the event that the bolt was on the skinny side of the tolerance. That didn't work out and I ultimately had to open it to a full 1/4" to get the bolt to slide through.
Back to the work bench where I installed the new bushings. The fit was free of any play between that bases and the bushing and between the bushing and the bolt.
The final task was to eliminate the sliding motion of the sticks forward and aft on the 1/4" bolt between the stick bases and the control column. This was a pretty simple task of inserting AN960-416 and 416L washers to shim as much of the gaps away as possible. Obviously you can't get all of the gap out, so you have to take care of the last little bit by tightening the nut and pulling the control column in tighter on the stick bases.
I tuned this part of the system like you would a wheel bearing. I rotated the sticks left and right while tightening the nut one flat at a time. Once I began to feel tension on the sticks, I stopped and backed off one flat where I then dropped in the cotter key in to lock it into position.
The system linkages are tight (meaning no play) and very smooth (minus the drag of the TruTrak servos). You can work the left and right sticks in opposition directions, like driving a bull dozer, and you won't find any play. You can go all the way out to the control surface and hold it tight while wiggling the stick and not find any play between the control surface and stick. I'm very happy with the outcome.
This wasn't a terrible change to make and if you have the seats out and access to a lathe, you could probably do it in less than a day. You certainly could do it on a drill press with some forethought. creative jigs, patience, and a few sacrificed pieces of delrin while you traverse the learning curve, but the lathe is certainly the fastest and easiest.
I'd do it again... Glad it turned out the way it did.
Phil
<image001.png>
<image002.png>
On Sat, Feb 13, 2016 at 8:08 PM, Phillip Perry <philperry9(at)gmail.com (philperry9(at)gmail.com)> wrote:
I have some delrin coming and I'm planning on making them for my sloppiness.
I'm planning on reaming the bell crank to 3/8 and then seeing how well a 3/8 delrin rod fits. If it's still too loose, I have a 7/16 rod coming in the mail too. I'll be able turn it down to fit or possibly it would fit without any working (though I doubt it).
Once I find the rod that fits best, then I'll ream the center on a friends lathe. I have a 3/16" reamer that will work, but I plan on using another reamer that's 11/64 (1/64 under sized) to see how it fits first. Then if it's too tight I'll open it up to the full 3/16 with the other reamer.
I'll probably have a report on how well it works in the next 2 weeks or possibly late next week.
Phil
Sent from my iPhone
h --
EE Gifts!)
on
r> ed
://www.buildersbooks.com" rel="noreferrer" target="_blank">www.buildersbooks.com
ion" rel="noreferrer" target="_blank">http://www.matronics.com/contribution
-Matt Dralle, List Admin.
=============
br> ?RV10-List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?RV10-List
=============
S WEB FORUMS -
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=============
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ion" rel="noreferrer" target="_blank">http://www.matronics.com/contribution
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Strasnuts
Joined: 10 Feb 2009
Posts: 502
Location: Salt Lake City, UT
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| Posted: Thu Feb 25, 2016 12:08 pm Post subject: Re: Control Stick Slop - Bushings |
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Nice work Phil!
Delrin is an amazing material in my opinion. I really don't think mine will ever wear out. I bet I did the swap more than 350 hours ago and mine feels EXACTLY the same as it did after installation. If anything was wearing down I think you would instantly feel the slop again.
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RV-10 SB N801VR Flying
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Kellym
Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
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| Posted: Thu Feb 25, 2016 6:44 pm Post subject: Control Stick Slop - Bushings |
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I agree, Delrin is an amazing material, and it is rather hard as a
plastic goes. Certainly harder than the UHMW that Vans uses for some
friction sizes to prevent wear.
It also has had weird uses, like the Army had disks molded from Delrin
with a knife edge on the inner diameter. Purpose was to allow you to
light it on the knife edge to use as a heating element to warm C rations
in the winter.
On 2/25/2016 1:08 PM, Strasnuts wrote:
| Quote: |
Nice work Phil!
Delrin is an amazing material in my opinion. I really don't think mine will ever wear out. I bet I did the swap more than 350 hours ago and mine feels EXACTLY the same as it did after installation. If anything was wearing down I think you would instantly feel the slop again.
--------
40936
RV-10 SB N801VR Flying
530 hours
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=453187#453187
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