The Official Tube Bending Thread

Right. When doing road race tech inspections, we drill inspection holes in straight sections of the bars, away from bends and tube joints. For NHRA inspections, we do not drill inspection holes at all.

That's a useful formula. FWIW, some racing sanctioning bodies actually limit the bend radius to a minimum size. For instance, NASA (road racing) specifies a minimum of 3xOD for roll cage bend radii.

 

Nice!!

Thanks, it's always good to hear from you guys!

 

What diameter? I bend 1.625 dia X .083 4130N on Hossfeld 6"R dies. I bet they are being conservative for their safety against complaints, because I've run into trouble on other sizes because of variations in the material hardness as mentioned by Baleigh Inc. For example, I bent lots of 1.5 X .058 4130 on 6"R, then suddenly one day it started kinking and wouldn't stop. We decided is was the material and I had to change all my designs to 7.5" R on that material and buy new dies.

 

Yes...I have taken a few phone calls in my day, from upset customers who have been burned by the 1 5/8" x 5.5 CLR die.

 

I also have not had any issues bending 1.625"x.083" CM on our non-mandrel bender with a 6" centerline radius. I prefer to use our mandrel bender because it gives me more control and a better-quality bend, but the non-mandrel bender provides good results.

yoyodyne, I have had the same issues with 1.5"x.058" on the non-mandrel bender with the 6" die. It's just a little too thin for angles over 75* or so. .065" wall bends better if you want to keep the tighter bend radius.

 

Thanks for the info

 

Any other questions on the art of tube bending? I'm here to help. Ask away!

 

I would still like to see some pics of "sand bent" exhaust that has a tight radius. Guys say they can do it, but I have not seen pictures of "tight bends"

 

Great thread, I love being able to ask those in the know questions.

 

I do have a question-I am putting a tubing structure in my '35, and am using 1' X 1" .065 tubing-I am using a Pro Tools HMP-200 Bender, w/a 6" radius die-so far so good, but:

My challenge is to make a more gradual bend, say, 18-22" radius-I only need to make two of them, and I am at a loss on how to do this with this Bender-looks like the Harbor Freight tubing roller would work, but it looks like it only does round tubing-any thoughts? I hate to buy another Bender for two pieces, but..........

 

Yes, 18" to 22" radius bends could be done very easy on any inexpensive roll bender with standard tooling. I'm sure there are enough people on this board in your area with a small roll bender.

 

Thanks, I'll try the local HVAC Shop-

 

Not sure an HVAC shaop would have a roll bender. They would probably have a slip roll though.

 

does anyone know where I can get a 1" tube die at 2" CL radius? I haven't bought a bender yet but I have a big job that I'm going to do, and the die is a priority. or anyone who makes custom dies?

3" seems to be standard for 1" tube but I need tighter.

 

That is pretty tight for 1" tube. What is your wall thickness?

You will need at least .083" wall to get a descent bend on a 2" CLR. Tell me a little more about your application, what are you making?

 

I've been a car builder for years but I have a pretty big job thrown at me to possibly build a bunch of custom display units with 1" tube on each side, 4 bends into a rectangle with parts hanging in between. theirs are welded at the corners because the guy making the prototype is a cheater. it needs to be super tight bends so there is max usable area to hang parts on the end. .083 wall is doable, strength isn't an issue for this.

 

Cool, if you can live with an .083 wall thickness, you should be ok. I have sold tons of benders to guys doing display racks, and a 3" CLR is a more common size. If you go with a 3" CLR you can get away .065" wall material.

Food for thought

 

so you can make a 2" clr? what machine am I looking at for that $$ wise? I'm still trying to do this on a budget.

 

PM sent

 

I just emailed you. thanks

 

Hey Shane,


My question is how much torque is involved to bend 1.750” OD X .083” WALL DOM tube @ 6” RAD. (approx. NHRA /SCTA cage material. I don't have the rule books.) I'm building a mandrel bender, I'm to cheep to buy, and am dome scratching on the length of the lever arm needed. The Machinery's handbook is insuficent in that all the formulas don't take into account bending around a radi.


Thanks for reading.


Tork

 

Tork,

I'm not sure on that one. All of the manual rotary draw benders I have experience with work off of compound leverage, kinda like an old 70's car jack. 1.75" x .083 wall can be easily bent with these types of benders. You would not need a mandrel inside of the tube on a 6.25 or a 6.5" radius. Are you locked in at 6'?

Will your bender be a rotary draw or a rotary compression bender? Manual, hydraulic or electric?

 

Here's a couple of pics of the new roll cage on my altered made from 1 5/8" x .083" CM tubing, I have a JD2 model 3 mechanical bender with a 180 deg x 4 1/2" radius die, I used a 4 1/2' long lever extension pipe, and it was relatively easy to bend the tubing.

 

Are you sure that is a 4.5 CLR?

 

Here's the die, JD2 no longer makes this die.

 

Thanks for the response Shane, and no, not locked in to bend radi or tube dimensions. Mostly looking for ball park numbers so I don't build a yard ornament. I think what I have in mind would be a rotary draw type of deal, but I am not exactly sure. Plan to have a hook anchor on the inside die and apply torque with a hydraulic cylinder. A moving die on the outside at the bend and stationary mandrel on the inside of the tube. I would like very much to bend up to 2.5” thin wall at a tight radi for header applications. But this would be primarily a chassis and cage application. Have you ever had a pressuer gauge on any of the hydro. converted benders? The lever arm on most of those benders look like 12” or so and with a standard Port-a-power 1” cyl the torque would be the gauge reading.


Ken, the bends on your cage look great, and the hole deal looks like a wild ride. What are ya going to put in the middle to make noise with?


Tork

 

To start out with I'm using a tame lil .030" over 302 that pushed a 3200lb 66 mustang I used to have to 12.0's, should do pretty good in a car that's around half the weight of the mustang, eventually a alky injected 408" sbf with yates heads.

 

Nice!

 

Kenneth, real nice bend ups - position & fittment dude..!

But do your nose & lungs a favor - loose the old paint at least 1 inch back from were you are going to weld your seams.

One more thing - if you have a caliper, could you measure across the middle of your bends ?? - measure the inside ( thinner ) and then 90 deg's across.

Nothin wrong, just somthing I like to check on 4130N & 1020 DOM bends.

 

Thanks.

I plan on removing more paint around the joints before welding.

I'll get and post the measurements for you tomarrow (I also have a piece of 1 5/8" x .134" wall 1020 DOM tube that was bent with the same die, I'll get, and post those for you also).