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a.s.elliott(at)cox.net
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 Posted: Tue Jul 31, 2007 4:44 pm Post subject: Reaming aileron bellcrank for bushings? |
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I have two built-up aileron bellcranks nicely reamed out to 6.4mm (=.252 in). Unfortunately, I now find that the bushing material I have mic's out at .2535. I am assuming that this hole is supposed to be .002 bigger than the bushing. A 6.5mm reamer (expensive!) is .256, while an F drill that I have already is .257. Can I get away with the F drill?
Andy Elliott, Mesa, AZ
N601GE (reserved)
601XL/TD/QB, Corvair, building...
[quote][b]
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leinad
Joined: 19 Sep 2006
Posts: 283
Location: Central Virginia
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| Posted: Tue Jul 31, 2007 5:29 pm Post subject: Re: Reaming aileron bellcrank for bushings? |
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Andy,
I think you're hole is OK. It's what is called an interference or press fit. The hole has to be smaller than the part. It shouldn't take much force to press fit the bushing in the hole. Mine was the same way and the bolt turns freely in the bushing. I think the idea is the steel bolt should turn against the bushing, and not the aluminum.
Someone correct me if I'm wrong.
Dan
| Quote: | I have two built-up aileron bellcranks nicely reamed out to 6.4mm (=.252 in). Unfortunately, I now find that the bushing material I have mic's out at .2535. I am assuming that this hole is supposed to be .002 bigger than the bushing. A 6.5mm reamer (expensive!) is .256, while an F drill that I have already is .257. Can I get away with the F drill?
Andy Elliott, Mesa, AZ
N601GE (reserved)
601XL/TD/QB, Corvair, building... |
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Scratch building XL with Corvair Engine |
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lwinger
Joined: 21 Jun 2006
Posts: 229
Location: Tustin, CA
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| Posted: Tue Jul 31, 2007 8:32 pm Post subject: Reaming aileron bellcrank for bushings? |
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Andy,
I am just about one week ahead of you on this one. I, too, reamed my bellcrank with the hard-to-locate 6.4mm reamer -- only to discover that the bushing for ZAC wouldn't fit. I made another trip to McMaster-Carr in LA and got the 6.5mm and it works perfectly.
While the F bit would probably work, I personally opted for the greater precision of the reamer. Drill bits tend to make holes that are oblong.
If you, or anyone on the list, would like to borrow it, please just contact me off list and we can exchange info. No need in 20 of us having multiple specialty tools like this reamer.
Larry Winger
Tustin, CA
Scratch building 601XL/Corvair
Control surfaces and wings spars complete
Making wing ribs
On 7/31/07, Dr. Andrew Elliott <a.s.elliott(at)cox.net (a.s.elliott(at)cox.net)> wrote: [quote] I have two built-up aileron bellcranks nicely reamed out to 6.4mm (=.252 in). Unfortunately, I now find that the bushing material I have mic's out at .2535. I am assuming that this hole is supposed to be .002 bigger than the bushing. A 6.5mm reamer (expensive!) is .256, while an F drill that I have already is .257. Can I get away with the F drill?
Andy Elliott, Mesa, AZ
N601GE (reserved)
601XL/TD/QB, Corvair, building...
[b]
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Larry Winger
Tustin, CA
Plans building 601XL/650 with Corvair
Installing fuel system
www.mykitlog.com/lwinger |
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lwinger
Joined: 21 Jun 2006
Posts: 229
Location: Tustin, CA
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| Posted: Tue Jul 31, 2007 8:33 pm Post subject: Reaming aileron bellcrank for bushings? |
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Dan,
I'm no expert on this, but I did talk with one of the guys in the Zenith shop. I was told that the idea is that the bushing should be able to turn freely (without slop). The idea is to reduce the wear on the bolt altogether. Like you, I'm open to correction if I'm wrong.
Larry Winger
601XL/Corvair
Tustin, CA
On 7/31/07, leinad <leinad(at)hughes.net (leinad(at)hughes.net)> wrote: [quote]--> Zenith-List message posted by: "leinad" <leinad(at)hughes.net (leinad(at)hughes.net)>
Andy,
I think you're hole is OK. It's what is called an interference or press fit. The hole has to be smaller than the part. It shouldn't take much force to press fit the bushing in the hole. Mine was the same way and the bolt turns freely in the bushing. I think the idea is the steel bolt should turn against the bushing, and not the aluminum.
Someone correct me if I'm wrong.
Dan
| Quote: | I have two built-up aileron bellcranks nicely reamed out to 6.4mm (=.252 in). Unfortunately, I now find that the bushing material I have mic's out at .2535. I am assuming that this hole is supposed to be .002 bigger than the bushing. A 6.5mm reamer (expensive!) is .256, while an F drill that I have already is .257. Can I get away with the F drill?
Andy Elliott, Mesa, AZ
N601GE (reserved)
601XL/TD/QB, Corvair, building...
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Scratch building XL with Corvair Engine
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=126802#126802 [quote][b]
| | - The Matronics Zenith-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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_________________
Larry Winger
Tustin, CA
Plans building 601XL/650 with Corvair
Installing fuel system
www.mykitlog.com/lwinger |
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Geoff Heap
Joined: 12 Jan 2006
Posts: 266
Location: Lindenwold, New Jersey
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| Posted: Wed Aug 01, 2007 3:36 am Post subject: Re: Reaming aileron bellcrank for bushings? |
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Andy You may as well push it in now, press fit. I see one other choice. Get the 6.5 reamer. Don't try to put the "F" drill in the hole. It will screw itself in like a self tapping screw and RIP the material out of the hole...Geoff
do not archive
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dfmoeller
Joined: 19 Jun 2006
Posts: 60
Location: Austin, TX
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| Posted: Wed Aug 01, 2007 4:39 am Post subject: Re: Reaming aileron bellcrank for bushings? |
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I just assembled this area in a wing I've had to rebuild.
The way that bushing works is that the bolt clamps the bushing solid with the L brackets. This is obvious from the fact that the bushing is a slight bit longer than the stackup being clamped. The bearing surface is between the blocks on the bellcrank and the bushing. An interference fit is too tight. What you want is the bushing to just slide into the blocks with as little slop as possible. I would ream.
The downside to making it too big, even a couple thousandths, will be sloppy aileron control, maybe not the end of the world!
Doug
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leinad
Joined: 19 Sep 2006
Posts: 283
Location: Central Virginia
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| Posted: Wed Aug 01, 2007 6:35 pm Post subject: Re: Reaming aileron bellcrank for bushings? |
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Doug,
Perhaps you have a different version of the drawings. My drawings date 12/03 don't stack up that way at all.
The 3 aluminum parts 1/4 + 1/8 + 1/4 = .625
Then the drawing calls for .012 inches of the bushing sticking out past the aluminum.. This gives .649.. inches. THis is equal to 16.48 mm. The drawing also says the bushing is 16.5 mm long.
This is all on drawing 6w10.
Then on drawing 6w6 it shows the brackets also 16.5 mm appart.
So the drawings call for line on line to 2 thou under depending on which drawing to believe. In the machine shop that's called a slip fit.
I think the better assembly would be a press fit for the bushing and a slip fit for the "sandwhich" between the brackets. (just as the drawings show) The aluminum makes a terrible bearing. Steel bolt sliding against the bushing should last much longer. Check any machinist handbook on this.
Dan
| Quote: | I just assembled this area in a wing I've had to rebuild.
The way that bushing works is that the bolt clamps the bushing solid with the L brackets. This is obvious from the fact that the bushing is a slight bit longer than the stackup being clamped. The bearing surface is between the blocks on the bellcrank and the bushing. An interference fit is too tight. What you want is the bushing to just slide into the blocks with as little slop as possible. I would ream.
The downside to making it too big, even a couple thousandths, will be sloppy aileron control, maybe not the end of the world!
Doug |
| | - The Matronics Zenith-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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_________________
Scratch building XL with Corvair Engine |
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dfmoeller
Joined: 19 Jun 2006
Posts: 60
Location: Austin, TX
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| Posted: Thu Aug 02, 2007 4:54 am Post subject: Re: Reaming aileron bellcrank for bushings? |
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My 601 was made from a factory kit by the builder (not me), original issue 2001 vintage. I managed to do some wing damage, so some repairs are being made. I ordered the most recent 3/06 drawings in the process. Here is what I've found.
0. In looking at the 1st and last set of drawings, there is no difference in dimensions on the two sets.
1. My bushings slide easily into the spacer blocks. There is no discernable slop and certainly not an interference fit. There is a little grease between the bushing and spacers.
2. The vertical stack up of the spacers and bellcrank are less than the bushing - meaning the angle brackets can only clamp the bushing when torqued (since the vertical displacement between brackets is exactly the same measurement as the bushing, any pressure at all will ensure clamping).
3. The angle brackets are installed on the rib (per the assembly instructions) by torquing the bushing between the brackets and then riveting in place - guaranteeing an immobile bushing.
4. The following statement was added to the drawing 6W10 sometime between my two issues: "6W10-3 bearing surface is between bushing & spacer".
Intuitively, I too would have thought the bearing surface would have been designed to be between the steel bolt shank and bushing (easily replaceable), but not so.
Doug
| leinad wrote: | Doug,
Perhaps you have a different version of the drawings. My drawings date 12/03 don't stack up that way at all.
The 3 aluminum parts 1/4 + 1/8 + 1/4 = .625
Then the drawing calls for .012 inches of the bushing sticking out past the aluminum.. This gives .649.. inches. THis is equal to 16.48 mm. The drawing also says the bushing is 16.5 mm long.
This is all on drawing 6w10.
Then on drawing 6w6 it shows the brackets also 16.5 mm appart.
So the drawings call for line on line to 2 thou under depending on which drawing to believe. In the machine shop that's called a slip fit.
I think the better assembly would be a press fit for the bushing and a slip fit for the "sandwhich" between the brackets. (just as the drawings show) The aluminum makes a terrible bearing. Steel bolt sliding against the bushing should last much longer. Check any machinist handbook on this.
Dan
| Quote: | I just assembled this area in a wing I've had to rebuild.
The way that bushing works is that the bolt clamps the bushing solid with the L brackets. This is obvious from the fact that the bushing is a slight bit longer than the stackup being clamped. The bearing surface is between the blocks on the bellcrank and the bushing. An interference fit is too tight. What you want is the bushing to just slide into the blocks with as little slop as possible. I would ream.
The downside to making it too big, even a couple thousandths, will be sloppy aileron control, maybe not the end of the world!
Doug |
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http://www.matronics.com/Navigator?Zenith-List |
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lwinger
Joined: 21 Jun 2006
Posts: 229
Location: Tustin, CA
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| Posted: Thu Aug 02, 2007 5:36 am Post subject: Reaming aileron bellcrank for bushings? |
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FWIW, I came to the same conclusion after multiple re-readings of the 6W10 plans (3/2006 revision), and a call to Zenith. They apparently want to protect the bolt from any wear, whatsoever. That is only accomplished if the bushing can spin freely in the bellcrank block and is then immobilized through the clamping action provided between the aileron bellcrank supports (6W6-11).
Larry Winger
Tustin, CA
601XL/Corvair
On 8/2/07, dfmoeller <dfmoeller(at)austin.rr.com (dfmoeller(at)austin.rr.com)> wrote: [quote]--> Zenith-List message posted by: "dfmoeller" <dfmoeller(at)austin.rr.com (dfmoeller(at)austin.rr.com)>
My 601 was made from a factory kit by the builder (not me), original issue 2001 vintage. I managed to do some wing damage, so some repairs are being made. I ordered the most recent 3/06 drawings in the process. Here is what I've found.
0. In looking at the 1st and last set of drawings, there is no difference in dimensions on the two sets.
1. My bushings slide easily into the spacer blocks. There is no discernable slop and certainly not an interference fit. There is a little grease between the bushing and spacers.
2. The vertical stack up of the spacers and bellcrank are less than the bushing - meaning the angle brackets can only clamp the bushing when torqued (since the vertical displacement between brackets is exactly the same measurement as the bushing, any pressure at all will ensure clamping).
3. The angle brackets are installed on the rib (per the assembly instructions) by torquing the bushing between the brackets and then riveting in place - guaranteeing an immobile bushing.
4. The following statement was added to the drawing 6W10 sometime between my two issues: "6W10-3 bearing surface is between bushing & spacer".
Intuitively, I too would have thought the bearing surface would have been designed to be between the steel bolt shank and bushing (easily replaceable), but not so.
Doug
leinad wrote:
| Quote: | Doug,
Perhaps you have a different version of the drawings. My drawings date 12/03 don't stack up that way at all.
The 3 aluminum parts 1/4 + 1/8 + 1/4 = .625
Then the drawing calls for .012 inches of the bushing sticking out past the aluminum.. This gives .649.. inches. THis is equal to 16.48 mm. The drawing also says the bushing is 16.5 mm long.
This is all on drawing 6w10.
Then on drawing 6w6 it shows the brackets also 16.5 mm appart.
So the drawings call for line on line to 2 thou under depending on which drawing to believe. In the machine shop that's called a slip fit.
I think the better assembly would be a press fit for the bushing and a slip fit for the "sandwhich" between the brackets. (just as the drawings show) The aluminum makes a terrible bearing. Steel bolt sliding against the bushing should last much longer. Check any machinist handbook on this.
Dan
> I just assembled this area in a wing I've had to rebuild.
>
> The way that bushing works is that the bolt clamps the bushing solid with the L brackets. This is obvious from the fact that the bushing is a slight bit longer than the stackup being clamped. The bearing surface is between the blocks on the bellcrank and the bushing. An interference fit is too tight. What you want is the bushing to just slide into the blocks with as little slop as possible. I would ream.
>
> The downside to making it too big, even a couple thousandths, will be sloppy aileron control, maybe not the end of the world!
>
> Doug
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Read this topic online here:
[b]
| | - The Matronics Zenith-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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_________________
Larry Winger
Tustin, CA
Plans building 601XL/650 with Corvair
Installing fuel system
www.mykitlog.com/lwinger |
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