Roller Bender for square tubes

**Bullet500** · Feb 17, 2016, 11:09 AM

Hello all,

I want to bend some square tubing to make a pedal car for my grand sons and need a roller bender for that and maybe for other projects in future.
So I came up with the idea to make one myself and as I have practically all the parts now I want to show you my progress.

Roller Bender for square tubes-square-tube-roller.jpg

the idea

Roller Bender for square tubes-parts-square-tube-roller.jpg

important parts

Roller Bender for square tubes-get-idea-.jpg

impression when finished

**AdrianH** · Feb 24, 2016, 04:15 PM

I may be wrong on this point, but looking at other benders that do square tube, if you wish to get a tight'ish bend on square tube I think you need a ridge on the middle bender to make the inside wall collapse in on it self. I think a ridge of 3 or 4 mm could be enough depending on what wall thickness you use.

If doing a large radius I do not think it would be an issue.
Also some guides to keep it straight., these could be rings you can move and clamp into position to suit the size of tube etc.

Just ideas to throw out there.

Adrian

I have just built a bender myself, of a slightly different design and desperately trying to make new formers for different profiles.

**astroracer** · Feb 24, 2016, 07:24 PM

Bullet, beautiful design and execution BUT... Like adrian alluded to, bending square tubing is not as simple as rolling it around a mandrel. The tubing HAS to run in a guided roller to keep it from flattening out. AND it will have to have the inner wall depressed to "take up" the extra material that will be on the inside of the bend.
Do some looking on Google for sq. tube benders and you will see the high sided rollers that are used to keep the sides of the tubing from pooching out during the bending process. Just trying to help...
I pulled a pic from the Pro-Tools site. http://shop.pro-tools.com/pages/shop...e-of-pro-tools
This is a pic of their roller dies for their large radius bender (which your design emulates.)

You can see the deep groove used to control the profile of the sq. tube during bending. This is what you will need to have to roll your bends.
Mark

**Bullet500** · Feb 25, 2016, 03:39 AM

Hello,

Thanks for the comments, I know it's better to have profiled rollers but than I have to make rollers for specific tube dimensions.
My intention is to use it only for larger radii and as you can see I have drilled small holes in the top near the fixed rollers and these are to fix hard wood or -plastic strips or blocks to guide the tube during bending instead of the profiled rollers.

Keep you informed.

**astroracer** · Feb 25, 2016, 06:00 AM

Yes, thanks for the insight. I was curious as to the purpose of those holes.

And keep us in the loop, definetly! You will have some developement to do to get this to work but it sounds like you have a handle on it. Good Job!
Mark

**AdrianH** · Feb 25, 2016, 11:03 AM

The blocks as guides would be a good idea, I am trying for s lightly different approach as I have 90 mm rollers only suspended at one side and I am going for clamping rings if I can as these.

Roller Bender for square tubes-ring-clamp-small.jpg

Plan is to use four two on each bottom roller.

Adrian

**Bullet500** · Jul 18, 2016, 01:14 PM

I finished the bender after using it to make the wheel to operate it.
The picture with the square tube was a trial to see how far it was able to bend a 25x2 mm square tube.
This is about R=300 mm but deformed to a trapezium shape as was to be expected.
The radius I want is about 1500 mm so that should be no problem.