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Benders and Bending Which bender is best? How do you use a bender? How do you calculate bends? Everything Bender related...


Benders and Bending Which bender is best? How do you use a bender? How do you calculate bends? Everything Bender related...

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  #1  
Old 01-22-2016, 11:36 AM
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Twisted bends, twisted mind?

JD2 Mod. 3 bending 1-1/2 and 1-3/4 round tube.
What the heck am I doing wrong, I always seem to have a slight twist when I do two bends. I use a plane of bend gage, the bender is bolted down and leveled using a carpenters level. My guess is when under tension the dies may not be parallel to the bender frame which is what I leveled. I guess I need to check that, good thing a wrote this out huh. Any other tips, insight, technique I need?
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Old 01-22-2016, 12:50 PM
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What type of tube? DOM? ERW?

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Old 01-22-2016, 12:59 PM
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Some ideas:
Make sure arms are straight and tightly bolted.
Space dies so they are centered between the arms.
Space ram or ratchet so it is centered between the arms.
Place the seam on the inside of the bend.
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Old 01-22-2016, 01:08 PM
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Quote:
Originally Posted by TheBandit View Post
Some ideas:
Make sure arms are straight and tightly bolted.
Space dies so they are centered between the arms.
Space ram or ratchet so it is centered between the arms.
Place the seam on the inside of the bend.
Yes, however, I never put the seam in compression or tension:
Seam on the side of the bend where possible...

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Old 01-22-2016, 01:31 PM
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ERW.
I typically put the seam to the inside. I have heard both inside and side orientation, I'll experiment with these options. Hmmmm......
I'll check the die location setup as far as being centered in the frame, double checking the ram also. Good thing I have a lathe sitting around I can make spacers with.
I have a bunch of tube to bend for a project soon so it's important I get this figured out.
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Old 01-22-2016, 01:33 PM
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How old is the bender? Check the holes in the arms were the main drive pins go through. I replaced a set of arms that were severely ovaled. Over years of bending. They loaded predominantly to one side. This caused my dies to be off axis from each other.
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Old 01-22-2016, 01:35 PM
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Model threes have a lot of slop from the factory in their pins. Make sure to support the tube before and after the die so as not to add leverage to the die hanging out of the bender.
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Old 01-22-2016, 03:17 PM
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I suppose a thesis could be written about appropriate seam placement when bending. I'd be willing to bet inside vs side would have negligible differences in strength or twist. Most likely this is an issue of parallelism/perpendicularity/alignment between the dies when bending.

One thing you can do to quantify the twist is bend a 180 and see if the legs are coplanar. If not, you are experiencing twist. If so, then you having an issue with rotation between bends - different problems with different solutions
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Old 01-22-2016, 03:29 PM
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I suppose it depends on the bender, with mine particularly in 2", I will get a more pronounced pull and crush effect with the seam in the die.

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Old 01-22-2016, 04:20 PM
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I had the same issue. Had to resquare my drive arms and tighten them down. Also the spacers made a huge improvement.
http://www.offroadfabnet.com/forums/...ghlight=spacer
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  #11  
Old 01-22-2016, 06:34 PM
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Quote:
Originally Posted by ScooteK View Post
How old is the bender? Check the holes in the arms were the main drive pins go through. I replaced a set of arms that were severely ovaled. Over years of bending. They loaded predominantly to one side. This caused my dies to be off axis from each other.
Quote:
Originally Posted by ScooteK View Post
Model threes have a lot of slop from the factory in their pins. Make sure to support the tube before and after the die so as not to add leverage to the die hanging out of the bender.
Basically brand new as are the dies. Building some spacers will be at the top of my list. I do try to support the tube to prevent the material weight influencing the bends. All good info thank you all.
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  #12  
Old 01-23-2016, 03:46 PM
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I have a PT 105 and I have tried just about everything I can think of and still get some rotation during a bend. I have been able to minimize it but it is still there. Placing the seam in a particular orientation is fine for single bends or multiple bends in the same plane.

I will soon be selling my PT105 and upgrading to a JD2 Model 32. I don't know for certain if the Model 32 will eliminate the rotation during bending, but it will solve another issue with the PT105 that has pissed me off for a long time.
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  #13  
Old 01-24-2016, 11:24 AM
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Was stupid busy in the shop yesterday, not bending tube, but I did give it a look. The die and follower are not centered in the frame so I'll start there making spacers. Keep moving forward.
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Old 02-16-2016, 11:20 AM
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Checked bolts, checked alignment, shimmed everything to rest in the center of the frame. Bent a front bumper hoop and it came out near perfect. We did find the dies don't sit parallel to the frame. So leveling the tube not the frame seemed to help with perfection. Definitely the dies and followers have what I would say is excessive hole to pin clearances. I'm learning and improving and I guess when I grow up I'll invest in a more rigid and precise bender.
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Old 02-16-2016, 11:37 AM
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...I guess when I grow up...
Never do that!
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  #16  
Old 02-16-2016, 12:25 PM
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Ha

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Never do that!
Please don't confuse "growing up" with not having fun. I will always be a kid at heart.
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  #17  
Old 02-16-2016, 12:54 PM
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Quote:
Originally Posted by Captainfab View Post
I don't know for certain if the Model 32 will eliminate the rotation during bending, but it will solve another issue with the PT105 that has pissed me off for a long time.
What issue would that be?
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  #18  
Old 02-18-2016, 07:18 PM
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The constant galling in the backing block.

Quote:
Originally Posted by TheBandit View Post
What issue would that be?
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  #19  
Old 02-19-2016, 09:56 AM
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How are you guys aligning your arms? Is registering the edge of the arms accurate enough or are you machining close-fit pins to engage the holes?

Similar question with the spacers; how do you ensure the tube CL is at the same location on both dies? Is measuring off of the bottom of the dies accurate enough?

I have some mild twisting with my PT105 too. Nothing terrible, but if I can spend an hour or so dialing in the machine to eliminate it - it would be worth it.
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  #20  
Old 02-22-2016, 10:07 PM
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Ive squared off the arm edge, and the die spacers, i just cut some spacers (that aren't even square cuts) just to elevate the dies off the bottom arms. So far so good. I did make a spacer for the follower dies too.
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