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View Full Version : Tube Bending minimum radius help needed



JoeFin
03-06-2015, 09:18 PM
I would like to bend some 1.375" x .080" Chromalloy tubing to 5 or 6" radius.

I will be making my own bending dies for this and will be using a Greenlee 555 Bender with a pinch roller like the one pictured below


http://d323w7klwy72q3.cloudfront.net/i/a/2013/20130312interstate/X9125.JPG


Is it do-able ? - or is there some rule of thumb minimum radius I would be exceeding. Sorry its virgin territory for me and thought I would ask before I start cutting the die

oldtiffie
03-06-2015, 09:24 PM
I am always amazed at how well and how little a radius automotive exhaust pipe/tube can be bent/formed.

Why not try a local shop for info and methods/processes?

Or a BBS for that sort of interest/work?

JoeFin
03-06-2015, 10:04 PM
I am always amazed at how well and how little a radius automotive exhaust pipe/tube can be bent/formed.




I don't believe a muffler shop worries about slight wrinkles or deformation of the tubing they use for your muffler.

But yes I've seen the discussions before claim they use a "Mandrel Bender"

Black_Moons
03-06-2015, 10:33 PM
How many tubes do you plan to bend? I have bent 1" tube with heat, sand filled to a 3" radius with no problem, first time, without a mandrel, just a template to check my curve, O/A torch for heat and bending the tube by hand.

cucvzuz
03-06-2015, 11:17 PM
Look at jd2 https://www.jd2.com/p-32-model-3-bender.aspx

Thay make an 1.375 x 5.5"R and a 6.5"R

.095 is stated minimum wall.

There are plans online to make the entire unit if you wanted.

Protools is also another option .

DR
03-06-2015, 11:26 PM
The manual for my Parker mandrel benders says if the wall divided by the tube OD is less than .07 you have unacceptable tube deformation without an internal mandrel.

I would have to check what radius dies Parker offers in that tube size to see if your radius is within their limits.

JoeFin
03-06-2015, 11:49 PM
The manual for my Parker mandrel benders says if the wall divided by the tube OD is less than .07 you have unacceptable tube deformation without an internal mandrel.

Thanks - I think that is the information I'm looking for. At .083 wall I should be good

JoeFin
03-06-2015, 11:50 PM
How many tubes do you plan to bend?

More then 1 or 2


http://i198.photobucket.com/albums/aa83/Freakindj/Chassie-30_zpsveysdmie.jpg

DR
03-07-2015, 10:30 AM
Thanks - I think that is the information I'm looking for. At .083 wall I should be good

.083/1.375 = .06

That's not in the acceptable range for bending without an internal mandrel.

astroracer
03-07-2015, 10:36 AM
Nice looking chassis. What are you building?
I have a Pro-Tools 105 bender and always use their available die centerline radii when designing tube frames or roll cages. I also have a Harbor Frieght tubing roller to make large radii bends. I am designing a tube frame for a Model A right now and it will require some large radii bends to fit the body contours.
http://images60.fotki.com/v224/photos/5/904975/13323720/28ja14_TOTALVEHICLE1-vi.jpg

http://images60.fotki.com/v361/photos/5/904975/13323720/28ja14_TOTALVEHICLE2-vi.jpg
Lets see some of your project!
Mark

astroracer
03-07-2015, 11:51 AM
Pro-Tools list of bending dies for a 1 3/8" O.D includes:
4 1/2" CLR minimum wall is .095
5" CLR minimum wall is .083
6" CLR minimum wall is .058
Using a 5" radius your .083 will be fine.
http://pro-tools.com/diesets.aspx

Black_Moons
03-07-2015, 02:15 PM
More then 1 or 2


http://i198.photobucket.com/albums/aa83/Freakindj/Chassie-30_zpsveysdmie.jpg

So, 4 by the look of it? Still doable with heat no problem. likely take you about as long to heat bend them as make the die.

d kirby
03-07-2015, 06:46 PM
JoeFin, you're going to have to help me out here and explain what is Chromalloy tubing. I have no idea what it is and have never worked with it.

Did you mean Chromoly? If in fact you are using chromoly, I have a little experiance using this in flat track race bike frames and it looks like overkill for what you are trying to build.

Is this frame that you are building for racing, where you need a material that is tough and light?
If not you may be better off using mild steel tubing and not 4130 chromoly.

I will wait for your reply on the material you are using before I say much more, but I know from experience if it is chromoly,you will not like the results from heating and bending and also with this material you only get one chance at the bend because once it is bent your not going to do much else with it.

Dave

JoeFin
03-07-2015, 07:02 PM
JoeFin, you're going to have to help me out here and explain what is Chromalloy tubing. I have no idea what it is and have never worked with it.

Did you mean Chromoly? If in fact you are using chromoly, I have a little experiance using this in flat track race bike frames and it looks like overkill for what you are trying to build.

Is this frame that you are building for racing, where you need a material that is tough and light?
If not you may be better off using mild steel tubing and not 4130 chromoly.

I will wait for your reply on the material you are using before I say much more, but I know from experience if it is chromoly,you will not like the results from heating and bending and also with this material you only get one chance at the bend because once it is bent your not going to do much else with it.

Dave


Yes Dave

It is Chromoly - you can blame "Spell Check" for Chromalloy

No at 112 lbs I don't think it is too heavy given the class was a minimum weight of 1000 lbs. The main consideration was to limit contortion to 1 deg per 5000 lbs of force. And No, that model has been scraped already when it was checked for aero

d kirby
03-07-2015, 08:58 PM
Thanks JoeFin that explains a lot lol !!!
Does that mean you are going in a completely different direction now, or are you still thinking of using chromoly?

Dave

JoeFin
03-07-2015, 10:03 PM
Thanks JoeFin that explains a lot lol !!!
Does that mean you are going in a completely different direction now, or are you still thinking of using chromoly?

Dave


No I'll still be using chromoly - just that I am considering a different bender

Given the shape of the Greenlee it could probably fetch $2500 on Eboner - that could buy a more suitable bender for the Chromoly

Too Bad - I've used the Greenlee on a bunch of DOM and HSM for SCCA, NHRA and various Rock-Crawler projects. Actually works rather well with "1 Button Operation" leaving a free hand to check the work with a protractor or measuring tape.

That or I could go ahead make the die and corresponding slip-sleeve and use the Greenlee

I'll let you know

Armilite
03-07-2015, 10:35 PM
If you look on ebay at Tube Bending Dies, Tube Benders, I believe the smallest Radius I have seen is 3" and go up from there. I'm looking at the JD2 Model 3 Tube Bender myself $295. Dies start out at about $135 and go up. There is some greenlee dies on ebay also.

http://www.ebay.com/itm/JD2-Model-3-Bender-Pipe-and-Tube-M3-/281615583383?pt=LH_DefaultDomain_0&hash=item419198c897

A good Tube Bending software is Bend Tech. Home 2D version was $75.
http://www.bend-tech.com/

Rich

Lee Cordochorea
03-10-2015, 07:32 PM
Fill the tubes with sand for an "internal mandrel."

JoeFin
05-02-2015, 05:23 PM
Thought you guys might like to see the finished 1.375 Tube bending die on my Greenlee 555 Bender


http://i198.photobucket.com/albums/aa83/Freakindj/Mobile%20Uploads/20150502_141432_zpsmyi0rcso.jpg

plunger
05-03-2015, 12:22 AM
What method did you use to make the die and shoe?

JoeFin
05-03-2015, 04:52 PM
I used 2 pieces of 1.375 Al plate and used my CNC to mill out a 3D half round. Then I just bolted them together onto the 1/4" x 4" mounting plate

8000 lines of code and a 5/8 ball mill for each half