• From: near Bellingham, WA
  • Registered: 2019-09-10
  • Posts: 71

Topic: Tube flattening from bending process

Hello everyone,
it's been a while since I've posted but I'm back and trying to make progress on my slow build again.

I've recently tested my tube bender with a piece of ERW tubing and I'm concerned about how much flattening I'm seeing on the outside radius of the curve.  I plan to use DOM tubing for the cage but I figured for practice / testing / measurement purposes there would be no discernable difference with ERW.
Am I wrong?  would the exact same dimension tube in DOM resist flattening better than ERW?  I'm using (and had intended to use for my build) 1.75 x .095 tubing and I already know I can mitigate the flattening by using .120 instead.  And I've already sent pictures of what I've got to Pagel so if he says mine are too squished that's exactly my plan.
But in the meantime, does anyone know, or would be willing to measure, what is an acceptable/normal amount of flattening of the tube around a curve?  I put a caliper across my test piece in the middle of the bend and what was 1.75" tube is now 1.625". Am I just paranoid or is this trash?

  • From: Newport News, VA
  • Registered: 2015-12-23
  • Posts: 620

Re: Tube flattening from bending process

What bender are you using?

That guy
  • From: near Bellingham, WA
  • Registered: 2019-09-10
  • Posts: 71

Re: Tube flattening from bending process

DirtyDuc wrote:

What bender are you using?

An Affordable Bender brand with a 7" die.

  • Registered: 2009-05-27
  • Posts: 361

Re: Tube flattening from bending process

Without a mandrel bender some inherent distortion/flattening is normal. DOM is definitely more rigid and less likely to flatten.
Ask Pagel for sure but it may be a normal condition wit h ERW. 
Manny

  • From: Camarillo, CA
  • Registered: 2021-03-26
  • Posts: 385

Re: Tube flattening from bending process

I've gotten very nice bends using a harbor freight "pipe kinker"... the crappy kind that's basically a hydraulic press with some dies. I've tried packing with sand, heating, and all sorts of other tricks but what works the best is tac welding the tube to the die at the center of the bend/top of the die and then proceeding to bend. It keeps it from lifting and therefore prevents it from kinking. I would never make an entire cage doing this because it's extremely slow, but it works great if I need to add a single piece to a cage. Not sure if this is helpful for your bender though.

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  • Mr.Yuck
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  • From: Brookeville, Md.
  • Registered: 2013-12-09
  • Posts: 1,012

Re: Tube flattening from bending process

Not sure it will pass tech it it flattens out. Check with tech

"get up and get your grandma outta here"
  • From: near Bellingham, WA
  • Registered: 2019-09-10
  • Posts: 71

Re: Tube flattening from bending process

I've received a response from Pagel:

"That bender doesn't have a real follower and isn't really a mandrel bender... Probably need to go to a better bender."

Hmm.