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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 03-16-2010, 03:40 PM
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Something new and strange...

So, just when it seems you have all the bugs worked out, something new arises. The phenomenon is that I'm bending a tube with a total of 4 bends, bend 1,2,&4 on the 0° plane, and the 3rd on a 90° rotation from the others. The parts I'm making are pairs, lefts and rights being mirror image, so the rotation is either 90° or -90°. The problem is that I am losing rotation somewhere. The lefts are under rotated and the rights are over rotated. (Or maybe thats the other direction) Anyway, the legs do not come out parallel. It's almost as if the bender is inputing a mild twist as it bends. Has anybody seen this? If so, any ideas what the root problem may be?

Some key note items: Pro Tools 105. Hydraulic. I just built a new stand to hold the bender and this is the first major project since switching to the new stand, but I can't see where that would affect it, but at the same time am almost sure this is the problem. I did just move into a new building, so maybe the building is cursed!

As always, any help is appreciated! I'm sure I'm overlooking something simple....
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Old 03-16-2010, 04:05 PM
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It sounds like your die is not level. Use a POB (plane of bend) bracket and an angle level and bypass the out of level problem all together.

After reading your post a second time, I am almost positive this is your problem.

.
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  #3  
Old 03-16-2010, 04:24 PM
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I am almost positive that you are correct, just not seeing it yet. I use a POB bracket and digital angle finder always. If the POB is zeroed before you start, and you rotate according to that, it shouldn't matter if the die is level, or should it?? I think I am overthinking myself here, I'll go back to basics and see what I come up with, but any input is appreciated, I'd like to think i am smarter then I am showing today!
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Old 03-16-2010, 04:43 PM
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Quote:
Originally Posted by raceplayhavefun View Post
I am almost positive that you are correct, just not seeing it yet. I use a POB bracket and digital angle finder always. If the POB is zeroed before you start, and you rotate according to that, it shouldn't matter if the die is level, or should it??.......
It would matter if your "flip" the tubing.
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  #5  
Old 03-16-2010, 04:54 PM
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No flips on this one. Just draw through from one bend to the next.

I'm used to working on a floor that is close to level and this one sucks. My cart is on wheels so I move it where I need to. Somehow I'm sure this is all related to being level, but still not clear in my mind, and I'm one of those guys that has to understand the "why"s of things.
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  #6  
Old 03-16-2010, 06:06 PM
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OK, Now this is just wierd. I've checked everything I can think of, played around with multiple angle finders, etc.

Then I noticed that as I'm bending the POB is slowly "unwinding". Turning counterclockwise as viewed from the start end of the tubing. So I tried several more bends, all with the same result. The tube is literally rotating as it bends. Several sample bends between 40° and 60° and the tube rotates about 0.5°. <EDIT> on a 90° bend it rotated the tube almost a full degree! <end edit> Thats a TON when added across several bends! Has anyone else experienced this? Any ideas how to fix it?

Last edited by raceplayhavefun; 03-16-2010 at 06:25 PM.
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Old 03-16-2010, 07:34 PM
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Yes I have experienced this myself as many others. I would check the parallelness of your arms. When bolting them together clamp them parallel before tightening the $hit out of them. If the 2 sets of arms are not parallel then the main die and follower die are going to be off axis from each other causing the corkscrew action. I dont have a level anything at my place, but with parallel arms and a POB its fine.

Edit>>> if your hydro, make sure your piston is centered on the pins during the push.
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Old 03-16-2010, 07:54 PM
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Thats what I was thinking. I'm guessing things got hit and banged when moving my shop to its new location. Back to square one I go!

Thanks for the assistance!
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Old 03-16-2010, 08:02 PM
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Quote:
Originally Posted by scootek View Post
Yes I have experienced this myself as many others. I would check the parallelness of your arms. When bolting them together clamp them parallel before tightening the $hit out of them. If the 2 sets of arms are not parallel then the main die and follower die are going to be off axis from each other causing the corkscrew action. I dont have a level anything at my place, but with parallel arms and a POB its fine.

Edit>>> if your hydro, make sure your piston is centered on the pins during the push.
Good point Andy
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  #10  
Old 03-16-2010, 08:24 PM
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What are you doing to ensure the arms are parallel? This may sound stupid (my questions usually do!) but what are we trying to get parallel, the horizontal surfaces or the arms all being in line with one another? I'm thinking its the latter....

Darm, this is what I get for going and changing something that was working fine!
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  #11  
Old 03-16-2010, 09:30 PM
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Problem has been diagnosed by others. The bender arms are twisting as the arm gets further away from closed position. My bender did this all the time and I machined a new set up altogether and have not had a single issue since.

To remedy it, I machined top and bottom plates and used multiple braces along the body. Everything was machined to ensure accuracy. I even drilled and tapped the bender arms and reinforced IT with plate as to keep it from twisting.

Lastly, I used a support plate under the hydraulic ram. That way when it extends, it is fully supported the entire amount and does not droop or sag as it extends (this is where my scissoring of the bender arms was happening).

Easy fix but took me a weekend of tinkering on the mill! ;-)

Grant
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Old 03-17-2010, 10:53 AM
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Jackalope, are you saying you support the body of the ram? I'm assuming thats what you mean, but some pictures would be great! I am seeing a day spent on the mill making bushings and supports.

Last edited by raceplayhavefun; 03-17-2010 at 11:48 AM.
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  #13  
Old 03-17-2010, 12:51 PM
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Quote:
Originally Posted by raceplayhavefun View Post
Jackalope, are you saying you support the body of the ram? I'm assuming thats what you mean, but some pictures would be great! I am seeing a day spent on the mill making bushings and supports.

You are correct in your assumption! I will see if I can get any pics posted. I can say that, without a doubt, the time making the frame on the mill was the best thing I could have done. I have had ZERO problems!

Grant
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  #14  
Old 03-17-2010, 04:53 PM
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So what I have noticed after much more screwing around with it today, is that the body of the hydr ram actually lifts when extending, not droop. Which follows with the fact that the tubing is twisting counterclockwise as viewed from the start end of the tubing. I found the post someone else started about using bushings for the main die, and am going to pursue that as well as some significant bracing. More pictures of what others have done would be greatly helpful!
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  #15  
Old 03-17-2010, 09:22 PM
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I will get some posted for you tomorrow. I took them with my phone so I hope they turn out okay. Stay tuned................
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  #16  
Old 03-17-2010, 11:59 PM
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I got the same issue. Will be watching this one closely
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  #17  
Old 03-18-2010, 04:24 AM
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Quote:
Originally Posted by scootek View Post
Yes I have experienced this myself as many others. I would check the parallelness of your arms. When bolting them together clamp them parallel before tightening the $hit out of them. ...Bla Bla .. .
I Totally agree with scootek .. I do alot of bending.. using JD2, air over and stock.. It shakes the shit out of everything.. Any time I change a die or project, I always re-check arms for parallel and re adjust if needed.. (keeps my plane to a min fault) not to mention wear and tear or type of tube ...



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Old 03-18-2010, 11:30 AM
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Alright fellas, here are the pics. I hope they turn out okay........
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  #19  
Old 03-18-2010, 11:33 AM
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Ooooooooooooohhh, these pics suck!!! Sorry. Hope you can make a little bit out of them.

Grant
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  #20  
Old 03-18-2010, 04:44 PM
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At this point, anything helps! Thanks so much!
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