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Jugle

Joined: 04 Aug 2007
Posts: 47
Location: Victoria, Australia

Posted: Fri May 09, 2008 11:31 pm Post subject: Bending- again...

Hi Scratchbuilders,



Well I've been following some of your suggestions using Dave Clay's brake, including the recommendation of leaving the flanges wider while bending, then trimming them down and Larry Winger's idea of putting the brake bolts through the metal. 



The bends are great when the flange is wide, but when trimmed back to 18mm to create angle sections, I end up with a nice gentle curve in the piece.



It seems to be within Bend Straightness tolerances as per the Construction Standards, but I'm wondering if yours are curved too and what the factory ones are like. Above all, will straightening that curve out when fixing put any undue stress on the structures?



Thanks, Glenn

_________________
Glenn Andressen
601XL- Rudder, Stabiliser parts completed, Wing ribs, nose ribs done, 70% Fuselage parts made.

Ron Lendon

Joined: 10 Jan 2006
Posts: 685
Location: Clinton Twp., MI

Posted: Sat May 10, 2008 8:14 am Post subject: Re: Bending- again...

That is just a normal occurrence of bending metal that way.  I normally overbend a little so the middle comes out right then open up the overbend areas by lightly hammering and checking often.



See example here:



http://mykitlog.com/users/display_log.php?user=rlendon&project=113&category=0&log=21203&row=312

_________________
Ron Lendon
WW Corvair with Roy's Garage 5th bearing
CH 601 XLB
N601LT - Flying
http://www.mykitlog.com/rlendon
Corvair Engine Prints:
https://sites.google.com/site/corvairenginedata/

Jugle

Joined: 04 Aug 2007
Posts: 47
Location: Victoria, Australia

Posted: Sat May 10, 2008 5:58 pm Post subject: Re: Bending- again...

Hi Ron,



 	  Ron Lendon wrote: 	
		  That is just a normal occurrence of bending metal that way.  I normally overbend a little so the middle comes out right then open up the overbend areas by lightly hammering and checking often.

	




Thanks, but I'm not quite clear on what you're saying. Are you flattening out the angle at the ends and trying to reduce the curve in this way?



Glenn

_________________
Glenn Andressen
601XL- Rudder, Stabiliser parts completed, Wing ribs, nose ribs done, 70% Fuselage parts made.

Ron Lendon

Joined: 10 Jan 2006
Posts: 685
Location: Clinton Twp., MI

Posted: Sat May 10, 2008 8:27 pm Post subject: Re: Bending- again...

I am talking about one bend.  I bend and check the angle in the middle of the length of the bend.  Then I qualify the rest of the piece so the same angle is represented for the entire length of the piece.  What this entails is checking and adjusting every inch or so along the whole length of the part. 



Is that more clear?

Jugle

Joined: 04 Aug 2007
Posts: 47
Location: Victoria, Australia

Posted: Sat May 10, 2008 11:48 pm Post subject: Re: Bending- again...

Yep, that part is clear Ron, but this only ensures an equal flange angle all the way along... the overall curve of along the length remains. It's simply not straight.



Glenn.



 	  Ron Lendon wrote: 	
		  I am talking about one bend.  I bend and check the angle in the middle of the length of the bend.  Then I qualify the rest of the piece so the same angle is represented for the entire length of the piece.  What this entails is checking and adjusting every inch or so along the whole length of the part. 



Is that more clear?

_________________
Glenn Andressen
601XL- Rudder, Stabiliser parts completed, Wing ribs, nose ribs done, 70% Fuselage parts made.

graeme(at)coletoolcentre.
Guest

Posted: Sun May 11, 2008 3:33 am Post subject: Bending- again...

Hi Glen



I to have the dave Clay brake mine is 2.5 meters long.

I have no touble bending  the longerons of the Ch701 end up 20mm x 22mm .o40 

angle.

I have bolts every .5meter

The bender is straight the bends are ok over the length but like you also 

have a Bow over the length

when removed from bender.

approx 20mm over 1.8meters.

I am sure when I assemble Aircraft they will straighten in construction.

But I to don't know why they end up with a bow.



Graemecns



---

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Sun May 11, 2008 12:29 pm Post subject: Re: Bending- again...

I wouldn't construct something with a bow (banana shape) in it. It should be straight. To correct the part you could try a small crimp every 6 inches til it's straight. To correct the brake, find out why the bend line you're putting in the part is not straight. Basically you're beding around a curved line instead of a stright line for some reason, hence the bowed banana. Either the bending tongue or the clamp is not straight, or the part is slipping in the brake (most likely in the middle where the most concentrated force is) or the clamp isn't holding it down hard enough. Doesn't take much at all to create a banana bow. One mm out of straight is enough to notice a slight banana. An extreme example of this is a potato chip (Pringles) or horse saddle shape; a compound curve, bent two ways at once. Another possible problem is the distance between the bending tongue (the part of the brake you lift on to make the bend) and the clamp face you're benidn around. As per Ron Lendon, you'll notice the middle doesn't make as tight of an acute angle as the ends when completed because the outer edges don't have any material on the outside to resist the bending force, hence the ends bend easier. With that in mind, and a continuous hinge style brake, the tongue is by definition quite far from the axis of rotation, possibly enough to create nice banana shaped parts. If you look closely at the design for the small Zenith brake, the axis of rotation of the tongue face is actually dead nuts at the edge of the clamp minus .050 for the material itself, and axis is about 5/32" above the brake bed to allow the face of the tongue to actually travel around the front edge of the 1/4" thick tongue; in a sense ROLLING the bend around the clamp face rather than just pressing it into it like a aluminum house siding bending brake.



That bow is why industrial bending brakes are so big and heavy just for bening fairly thin sheet, the beef is for the accuracy, and the accuracy comes from the pivot actually being in place where no piano hinge can exist and still act like a true bending brake, hense the pivots are at the ends. That's the main difference between Dave's brake and a industrial brake. Nothing wrong with Dave's brake though, obviously it's working for people, but you need to be aware of the difference between the two. And on the flip side, and industrial brakes weakness is in the fact that it's pivots are at the ends, hence, more beef is needed in the brake.



You need to go back and look at how to improve accuracy on that brake, it's not impossible, but you need to be aware of it to have repeatable quality results.



 	  graeme(at)coletoolcentre. wrote: 	
		  Hi Glen



I to have the dave Clay brake mine is 2.5 meters long.

I have no touble bending  the longerons of the Ch701 end up 20mm x 22mm .o40 

angle.

I have bolts every .5meter

The bender is straight the bends are ok over the length but like you also 

have a Bow over the length

when removed from bender.

approx 20mm over 1.8meters.

I am sure when I assemble Aircraft they will straighten in construction.

But I to don't know why they end up with a bow.



Graemecns



---

Jugle

Joined: 04 Aug 2007
Posts: 47
Location: Victoria, Australia

Posted: Sun May 11, 2008 2:30 pm Post subject: Re: Bending- again...

Hi Andy,



The bending brake components are straight, I've checked and re-checked with string lines and the bench it's on is level and straight. At first I thought the part was slipping, but my test with the bolts through the part being bent eliminated any slipping. It was only when I trimmed the part down to 18mm flanges that the bow occurred.



So it must relate to something else. I have tried bending 1200mm lengths at one end of the brake, rather than the middle, same result. Don't know, I'm stumped, thanks for your input.



If you or anyone else has any other ideas, I'd be glad to hear them.



Glenn.



 	  ashontz wrote: 	
		  I wouldn't construct something with a bow (banana shape) in it. It should be straight. To correct the part you could try a small crimp every 6 inches til it's straight. To correct the brake, find out why the bend line you're putting in the part is not straight. Basically you're beding around a curved line instead of a stright line for some reason, hence the bowed banana. Either the bending tongue or the clamp is not straight, or the part is slipping in the brake (most likely in the middle where the most concentrated force is) or the clamp isn't holding it down hard enough. Doesn't take much at all to create a banana bow. One mm out of straight is enough to notice a slight banana. An extreme example of this is a potato chip (Pringles) or horse saddle shape; a compound curve, bent two ways at once. Another possible problem is the distance between the bending tongue (the part of the brake you lift on to make the bend) and the clamp face you're benidn around. As per Ron Lendon, you'll notice the middle doesn't make as tight of an acute angle as the ends when completed because the outer edges don't have any material on the outside to resist the bending force, hence the ends bend easier. With that in mind, and a continuous hinge style brake, the tongue is by definition quite far from the axis of rotation, possibly enough to create nice banana shaped parts. If you look closely at the design for the small Zenith brake, the axis of rotation of the tongue face is actually dead nuts at the edge of the clamp minus .050 for the material itself, and axis is about 5/32" above the brake bed to allow the face of the tongue to actually travel around the front edge of the 1/4" thick tongue; in a sense ROLLING the bend around the clamp face rather than just pressing it into it like a aluminum house siding bending brake.



That bow is why industrial bending brakes are so big and heavy just for bening fairly thin sheet, the beef is for the accuracy, and the accuracy comes from the pivot actually being in place where no piano hinge can exist and still act like a true bending brake, hense the pivots are at the ends. That's the main difference between Dave's brake and a industrial brake. Nothing wrong with Dave's brake though, obviously it's working for people, but you need to be aware of the difference between the two. And on the flip side, and industrial brakes weakness is in the fact that it's pivots are at the ends, hence, more beef is needed in the brake.



You need to go back and look at how to improve accuracy on that brake, it's not impossible, but you need to be aware of it to have repeatable quality results.

_________________
Glenn Andressen
601XL- Rudder, Stabiliser parts completed, Wing ribs, nose ribs done, 70% Fuselage parts made.

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Sun May 11, 2008 2:42 pm Post subject: Re: Bending- again...

That's odd. Still there must be some kind of not-so-straight condition occurring that's only revealed once you take the extra meat off of the flange. That extra meat must be holding things straight. Still 20mm bow over 6 feet or less is fairly significant, but correctible with crimps. Better to correct the brake or process itself though. When I pull my parts out of the brake there's virtually no bowing. I can lay the part down on the worktable on either flange and it's flat. How much are you trimming it? Normally I bend my with about a 20mm flange and then trim.



 	  Jugle wrote: 	
		  Hi Andy,



The bending brake components are straight, I've checked and re-checked with string lines and the bench it's on is level and straight. At first I thought the part was slipping, but my test with the bolts through the part being bent eliminated any slipping. It was only when I trimmed the part down to 18mm flanges that the bow occurred.



So it must relate to something else. I have tried bending 1200mm lengths at one end of the brake, rather than the middle, same result. Don't know, I'm stumped, thanks for your input.



If you or anyone else has any other ideas, I'd be glad to hear them.



Glenn.



 	  ashontz wrote: 	
		  I wouldn't construct something with a bow (banana shape) in it. It should be straight. To correct the part you could try a small crimp every 6 inches til it's straight. To correct the brake, find out why the bend line you're putting in the part is not straight. Basically you're beding around a curved line instead of a stright line for some reason, hence the bowed banana. Either the bending tongue or the clamp is not straight, or the part is slipping in the brake (most likely in the middle where the most concentrated force is) or the clamp isn't holding it down hard enough. Doesn't take much at all to create a banana bow. One mm out of straight is enough to notice a slight banana. An extreme example of this is a potato chip (Pringles) or horse saddle shape; a compound curve, bent two ways at once. Another possible problem is the distance between the bending tongue (the part of the brake you lift on to make the bend) and the clamp face you're benidn around. As per Ron Lendon, you'll notice the middle doesn't make as tight of an acute angle as the ends when completed because the outer edges don't have any material on the outside to resist the bending force, hence the ends bend easier. With that in mind, and a continuous hinge style brake, the tongue is by definition quite far from the axis of rotation, possibly enough to create nice banana shaped parts. If you look closely at the design for the small Zenith brake, the axis of rotation of the tongue face is actually dead nuts at the edge of the clamp minus .050 for the material itself, and axis is about 5/32" above the brake bed to allow the face of the tongue to actually travel around the front edge of the 1/4" thick tongue; in a sense ROLLING the bend around the clamp face rather than just pressing it into it like a aluminum house siding bending brake.



That bow is why industrial bending brakes are so big and heavy just for bening fairly thin sheet, the beef is for the accuracy, and the accuracy comes from the pivot actually being in place where no piano hinge can exist and still act like a true bending brake, hense the pivots are at the ends. That's the main difference between Dave's brake and a industrial brake. Nothing wrong with Dave's brake though, obviously it's working for people, but you need to be aware of the difference between the two. And on the flip side, and industrial brakes weakness is in the fact that it's pivots are at the ends, hence, more beef is needed in the brake.



You need to go back and look at how to improve accuracy on that brake, it's not impossible, but you need to be aware of it to have repeatable quality results.

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Sun May 11, 2008 2:52 pm Post subject: Re: Bending- again...

Now that I think about it, I'm going to guess the radius of the bend in the middle is slightly larger than the radius at the ends because 1) the face of the tongue is a fairly good distance from the clamp and 2) the ends bend easier than the middle, hence you have a tighter bend at the ends than the middle. I'm going to guess the banana bow is to the inside of the bend rather than to the outside like a saddle. Correct?



Another thing to keep in mind is, the conditions of the initial few degrees of the bend are the setup for the rest of the bend. If the bend line and conditions of the bend are not right starting out it'll be messed up. Take a closer look at what's happening AS SOON as you start to lift the tongue of the brake, you might notice something.



It's not rocket science, but bending is actually more involved than you'd think. I'm just interested in what you're dealing with hear because I did a lot of designing and fiddling to get my brake right. It's not quite as simple as it would first seem to get good quality accurate bends. If I had a Dave Clay brake I'm sure I'd find things to tweak that I found with my own stretched Zenith design.



 	  Jugle wrote: 	
		  Hi Andy,



The bending brake components are straight, I've checked and re-checked with string lines and the bench it's on is level and straight. At first I thought the part was slipping, but my test with the bolts through the part being bent eliminated any slipping. It was only when I trimmed the part down to 18mm flanges that the bow occurred.



So it must relate to something else. I have tried bending 1200mm lengths at one end of the brake, rather than the middle, same result. Don't know, I'm stumped, thanks for your input.



If you or anyone else has any other ideas, I'd be glad to hear them.



Glenn.



 	  ashontz wrote: 	
		  I wouldn't construct something with a bow (banana shape) in it. It should be straight. To correct the part you could try a small crimp every 6 inches til it's straight. To correct the brake, find out why the bend line you're putting in the part is not straight. Basically you're beding around a curved line instead of a stright line for some reason, hence the bowed banana. Either the bending tongue or the clamp is not straight, or the part is slipping in the brake (most likely in the middle where the most concentrated force is) or the clamp isn't holding it down hard enough. Doesn't take much at all to create a banana bow. One mm out of straight is enough to notice a slight banana. An extreme example of this is a potato chip (Pringles) or horse saddle shape; a compound curve, bent two ways at once. Another possible problem is the distance between the bending tongue (the part of the brake you lift on to make the bend) and the clamp face you're benidn around. As per Ron Lendon, you'll notice the middle doesn't make as tight of an acute angle as the ends when completed because the outer edges don't have any material on the outside to resist the bending force, hence the ends bend easier. With that in mind, and a continuous hinge style brake, the tongue is by definition quite far from the axis of rotation, possibly enough to create nice banana shaped parts. If you look closely at the design for the small Zenith brake, the axis of rotation of the tongue face is actually dead nuts at the edge of the clamp minus .050 for the material itself, and axis is about 5/32" above the brake bed to allow the face of the tongue to actually travel around the front edge of the 1/4" thick tongue; in a sense ROLLING the bend around the clamp face rather than just pressing it into it like a aluminum house siding bending brake.



That bow is why industrial bending brakes are so big and heavy just for bening fairly thin sheet, the beef is for the accuracy, and the accuracy comes from the pivot actually being in place where no piano hinge can exist and still act like a true bending brake, hense the pivots are at the ends. That's the main difference between Dave's brake and a industrial brake. Nothing wrong with Dave's brake though, obviously it's working for people, but you need to be aware of the difference between the two. And on the flip side, and industrial brakes weakness is in the fact that it's pivots are at the ends, hence, more beef is needed in the brake.



You need to go back and look at how to improve accuracy on that brake, it's not impossible, but you need to be aware of it to have repeatable quality results.

Jugle

Joined: 04 Aug 2007
Posts: 47
Location: Victoria, Australia

Posted: Sun May 11, 2008 3:09 pm Post subject: Re: Bending- again...

 	  ashontz wrote: 	
		  Now that I think about it, I'm going to guess the radius of the bend in the middle is slightly larger than the radius at the ends because 1) the face of the tongue is a fairly good distance from the clamp and 2) the ends bend easier than the middle, hence you have a tighter bend at the ends than the middle. I'm going to guess the banana bow is to the inside of the bend rather than to the outside like a saddle. Correct? 	


I think the radius is larger in the middle of the bend... I've just been sitting here experimenting with pieces of paper and if you bend a right angle fold in a sheet of paper, with a sharper fold at the ends and less sharp in the middle, you get the bow I'm getting... so the brake must not be bending as sharp in the middle.



 	  ashontz wrote: 	
		  

Another thing to keep in mind is, the conditions of the initial few degrees of the bend are the setup for the rest of the bend. If the bend line and conditions of the bend are not right starting out it'll be messed up. Take a closer look at what's happening AS SOON as you start to lift the tongue of the brake, you might notice something. 	


Yep, good tip, I'll go and have another look.

_________________
Glenn Andressen
601XL- Rudder, Stabiliser parts completed, Wing ribs, nose ribs done, 70% Fuselage parts made.

raymondj(at)frontiernet.n
Guest

Posted: Sun May 11, 2008 3:21 pm Post subject: Bending- again...

Just a random thought. Is it possible some residual strain left in the 

material from the manufacturing process is manifesting it's self by changing 

how much the metal springs back.



One possible test, bend a number of shorter pieces at the same time over the 

same span on the break and see how the radii and spring back look on each 

piece. Might give you another bit of data.



Raymond Julian

Kettle River, MN



"Hope for the best,

but prepare for the worst."



do not archive



---

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Sun May 11, 2008 3:30 pm Post subject: Re: Bending- again...

No problem.



Yeah, that's what I figured. And yes the paper fold is a good analogy. No you have to think about how to bend the center evenly. Maybe something is simple as adding a 1/4" strip of metal on the tongue would help so that it pushes further into the clamp face. The problem you're experiencing is due to the large distance between the tongue face and the clamp face when the ton is in the 90 degree position, but the condition exists as soon as you start to bend, it just gets amplified. That smal distance is significant enough for the aluminum sheet to find a path of least resistance, and that path is, a larger radius bend in the middle. There's less resistance at the ends so it's not as much of a problem for the sheet to make the tigher radius bend on the outsides vs the insides.



You said you were testing it with strips, that's good. A good brake should show identical bends whether they were made at either end or the middle, they shouldbe identical. But the interesting thing about the Dave Clay brake is, the strips may appear identical, then you go and bend a full length piece and something aint right. The something that aint right is that large distance between the tongue face at 90 degrees and the clamp due to the fact that hinge point is below and oout rather than practically at the face and up. That's just the nature of that type of brake. At least you've identified the problem, now you just have to figure out how to fix it, and the fix may be on a piece by piece basis, but that's not terrible because really this problem only applies to fairly long pieces, and there's not that many of them. But figure for each long piece, it may take you 2 hours to make that part perfect, but that's time well spent, plus you'll know your brake better and be able to do it that much better in the future for the next part or if you have to remake something. Unless you're using a $10,000 industrial brake, making perfect parts on a 8' homemade brake is a bit of an artform, hopefully you can limit that to fiddling and setting up the brake up once and then going at it from there on out.



 	  Jugle wrote: 	
		   	  ashontz wrote: 	
		  Now that I think about it, I'm going to guess the radius of the bend in the middle is slightly larger than the radius at the ends because 1) the face of the tongue is a fairly good distance from the clamp and 2) the ends bend easier than the middle, hence you have a tighter bend at the ends than the middle. I'm going to guess the banana bow is to the inside of the bend rather than to the outside like a saddle. Correct? 	


I think the radius is larger in the middle of the bend... I've just been sitting here experimenting with pieces of paper and if you bend a right angle fold in a sheet of paper, with a sharper fold at the ends and less sharp in the middle, you get the bow I'm getting... so the brake must not be bending as sharp in the middle.



 	  ashontz wrote: 	
		  

Another thing to keep in mind is, the conditions of the initial few degrees of the bend are the setup for the rest of the bend. If the bend line and conditions of the bend are not right starting out it'll be messed up. Take a closer look at what's happening AS SOON as you start to lift the tongue of the brake, you might notice something. 	


Yep, good tip, I'll go and have another look.

Jugle

Joined: 04 Aug 2007
Posts: 47
Location: Victoria, Australia

Posted: Sun May 11, 2008 3:49 pm Post subject: Re: Bending- again...

You are right Andy and I think I have found it... because the brake is so long (10'), there is a lot of pressure in the middle and it is pulling the hinge away in the centre, very slightly. I'm using a steel hinge and steel rivets, but the rivet pitch is 2"- apparently too far apart. 



I'm going to remove the hinge, clean the faces and refit it with a rivet in between each existing one.



Thanks to everyone for their input and especially Andy. Bouncing it back and forth, I think we have found the answer. I'll let you know in a few days when I've fixed it.



Glenn.



 	  ashontz wrote: 	
		  No problem.



Yeah, that's what I figured. And yes the paper fold is a good analogy. No you have to think about how to bend the center evenly. Maybe something is simple as adding a 1/4" strip of metal on the tongue would help so that it pushes further into the clamp face. The problem you're experiencing is due to the large distance between the tongue face and the clamp face when the ton is in the 90 degree position, but the condition exists as soon as you start to bend, it just gets amplified. That smal distance is significant enough for the aluminum sheet to find a path of least resistance, and that path is, a larger radius bend in the middle. There's less resistance at the ends so it's not as much of a problem for the sheet to make the tigher radius bend on the outsides vs the insides.



You said you were testing it with strips, that's good. A good brake should show identical bends whether they were made at either end or the middle, they shouldbe identical. But the interesting thing about the Dave Clay brake is, the strips may appear identical, then you go and bend a full length piece and something aint right. The something that aint right is that large distance between the tongue face at 90 degrees and the clamp due to the fact that hinge point is below and oout rather than practically at the face and up.

_________________
Glenn Andressen
601XL- Rudder, Stabiliser parts completed, Wing ribs, nose ribs done, 70% Fuselage parts made.

Ron Lendon

Joined: 10 Jan 2006
Posts: 685
Location: Clinton Twp., MI

Posted: Sun May 11, 2008 4:23 pm Post subject: Re: Bending- again...

Good dialog Andy,



Here is a picture of the leaf brake I'm using.  Notice the angular structure (A-frame)  above and below the bending frame.  These are there specifically to tune out the feature you are experiencing.  There is a treaded nut at the center of the A-frame for adjustment.

100_0425.jpg

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ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Sun May 11, 2008 4:47 pm Post subject: Re: Bending- again...

Sounds good, Good luck. Should work fine, just keep a cloer eye on what's actually going on.



 	  Jugle wrote: 	
		  You are right Andy and I think I have found it... because the brake is so long (10'), there is a lot of pressure in the middle and it is pulling the hinge away in the centre, very slightly. I'm using a steel hinge and steel rivets, but the rivet pitch is 2"- apparently too far apart. 



I'm going to remove the hinge, clean the faces and refit it with a rivet in between each existing one.



Thanks to everyone for their input and especially Andy. Bouncing it back and forth, I think we have found the answer. I'll let you know in a few days when I've fixed it.



Glenn.



 	  ashontz wrote: 	
		  No problem.



Yeah, that's what I figured. And yes the paper fold is a good analogy. No you have to think about how to bend the center evenly. Maybe something is simple as adding a 1/4" strip of metal on the tongue would help so that it pushes further into the clamp face. The problem you're experiencing is due to the large distance between the tongue face and the clamp face when the ton is in the 90 degree position, but the condition exists as soon as you start to bend, it just gets amplified. That smal distance is significant enough for the aluminum sheet to find a path of least resistance, and that path is, a larger radius bend in the middle. There's less resistance at the ends so it's not as much of a problem for the sheet to make the tigher radius bend on the outsides vs the insides.



You said you were testing it with strips, that's good. A good brake should show identical bends whether they were made at either end or the middle, they shouldbe identical. But the interesting thing about the Dave Clay brake is, the strips may appear identical, then you go and bend a full length piece and something aint right. The something that aint right is that large distance between the tongue face at 90 degrees and the clamp due to the fact that hinge point is below and oout rather than practically at the face and up.

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Sun May 11, 2008 4:49 pm Post subject: Re: Bending- again...

Thanks Ron. Yeah, my bending brake is of this type, with the pivots at the ends. Depending on how I adjust it (or misadjust it  ) I can make a stright bend, and trough bend, or a saddle bend. Just depends on the tongue and clamp adjustments. Obviously we're interested in standard straight bends though. 



 	  Ron Lendon wrote: 	
		  Good dialog Andy,



Here is a picture of the leaf brake I'm using.  Notice the angular structure (A-frame)  above and below the bending frame.  These are there specifically to tune out the feature you are experiencing.  There is a treaded nut at the center of the A-frame for adjustment.

graeme(at)coletoolcentre.
Guest

Posted: Sun May 11, 2008 4:50 pm Post subject: Bending- again...

I tried putting a spacer in the centre of the bend of moving angle to 

tighten but seemed to make no difference??



Graemecns



---

Jugle

Joined: 04 Aug 2007
Posts: 47
Location: Victoria, Australia

Posted: Sun May 11, 2008 4:53 pm Post subject: Re: Bending- again...

That's a fine looking unit Ron. Yes I know all industrial brakes have the tensioner on them, where Dave's design uses the piano hinge to maintain even pressure, as long as you don't ask too much of it!



I may even shorten mine yet, as the 10' is probably not necessary as I first thought.



 	  Ron Lendon wrote: 	
		  Good dialog Andy,



Here is a picture of the leaf brake I'm using.  Notice the angular structure (A-frame)  above and below the bending frame.  These are there specifically to tune out the feature you are experiencing.  There is a treaded nut at the center of the A-frame for adjustment.

_________________
Glenn Andressen
601XL- Rudder, Stabiliser parts completed, Wing ribs, nose ribs done, 70% Fuselage parts made.

kmccune

Joined: 22 Sep 2007
Posts: 577
Location: Wisconsin, USA

Posted: Sun May 11, 2008 6:17 pm Post subject: Re: Bending- again...

I have been following this thread, because the bending brake as well as the flanging die really had me thinking for awhile. I also have a 10 ft Daves brake ( he really should trade mark that name  I had a 4 ft Al brake from A.Spruce that did just what yours is doing! Crap... don't buy one! Anyway my point is, fix the problem and keep the length. Is it necessary for this airplane...nope. But your friends will know that you have one and WILL come up with all manor of things to bend. I found out that a guy I've known for years builds mud trucks!!!Of course they have sheet metal....!



Kevin





 	  Jugle wrote: 	
		  That's a fine looking unit Ron. Yes I know all industrial brakes have the tensioner on them, where Dave's design uses the piano hinge to maintain even pressure, as long as you don't ask too much of it!



I may even shorten mine yet, as the 10' is probably not necessary as I first thought.



 	  Ron Lendon wrote: 	
		  Good dialog Andy,



Here is a picture of the leaf brake I'm using.  Notice the angular structure (A-frame)  above and below the bending frame.  These are there specifically to tune out the feature you are experiencing.  There is a treaded nut at the center of the A-frame for adjustment.

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