Technical dragster tube bending methods

hi all so after some completing im looking at building a hamb style dragster the shoulder hoop will be square back but I like a round cage what methods can be used to bend that sort of radius.

I was thinking of sand packing and heat around a wood form but I don't know if that's a no no in the NHRA/IHRA's eyes

 

I would invest in a tubing bender or have someone bend them for you.

 

Unless you want to spend big $$$ for a bender, pay someone to do it.

 

im looking at the ones marty strode built
http://www.jalopyjournal.com/forum/threads/front-engine-dragster-fed-build-ideas.941286/page-2

I like the cage style but I don't think there's a die for the jd2 model 3 that will bend that sort of radius that will fit me im a big guy for instance I need a 26" shoulder hoop

 

The shoulder hoop is two bends.
I guess at 26 inches it would flatten out across the back.
I think that a faint remember cell was thinking someone had a plan to build your own dies.
My guess was Pro Tools because that is what brand I have.

 

I would think a milling machine would be needed to make dies would it not. I could make a steel die by bending tubing with the right ID for my tubing in the shape I want and welding it to some plate but that would be the same sand/heat method or maybe a hydraulic press would work

 

I dont remember the milling machine part because I dont have one and kinda remember shit I could do that.

 

Maybe there is a limit on radius. My bender is not in front of me now.

 

jd2 model 3 biggest die is 7.5" radius that's most likely the die I will order anyway.

 

you can buy kits with pre-bent parts

http://www.ebay.com/bhp/roll-cage-kit

 

most of those are for full body cars even the pre bent dragster chassis will not work for me due to my size

 

low buck tools has the bender you want , I have had one for many years and it works great and make a perfect no crease bend for the pipe , do not buy the pipe bender that Hf sells as it will crease the pipe . as for sand bending I know of a few guys who have done it and they do not say a thing as long as the tube doesn't change shape ( turn oval )

 

I use a 6-5/8" center line radius die, and for the shoulder hoop I bend 2 - L's, and sleeve the joint. It makes it easier to figure, and fine tune the width, by trimming off the excess. Also bending 2 legs on the same tube, can sometimes be difficult to end up flat. This is 1- 3/4" tube. Good luck !

 

I was going to order a 1 3/4" die a smaller radius makes more sense as its more common for full body cars the bender will make me some money building cages for people. what did you use for the main hoop on the cage

 

I used 1-3/4 on the cage on the rear engine B-Ville car. Depending how tall your cage is, larger tube might be required to fit NHRA specs. Another trick I like to do, is fit a curved cross tube in the cage (see pic).

 

Per the NHRA rules 1.625 x .083 is the required minimum (using 4130), or .120 wall in mild steel, if the cage is over 18 tall from the shoulder hoop. I use a 7" CLR die for my single bend cages but the problem that you will have as a big guy is getting your shoulders out past the cage hoop. With the single bend the cage tapers in a lot more than with a double and if the shoulder hoop is low you will be well up into the narrow part of the cage hoop.

Roo

 

Built a nostalgia dragster based on a Chassis Research design. Found a local company that had a cnc controlled mandrel bender. Got perfect bends for $25 each. Gave them req'd dimensions to work from. I used 1.90 od X.125 wall mild steel tube. The company's main product was stainless hand rails for swimming pools.

 

Did you check the wall thickness on the .125 mild steel? Some sizes the wall being called out as .125 is much thinner and does not pass. For a mild steel door car using 1.625 you have to go with .134 wall because the .120 (.002 over minimum) measures .114 ( .006 under minimum)
DOM tubing holds wall pretty good but ERW can vari to what it is labled as

 

A tube bender that will make most of the bends is not really expensive. If I recall for less that 200 dollars one of the big catalog speed shops has one that is basically an arbor press with dies.

bending tight hops is not so easy and unless you do it a lot not really cost effective. I found a place on line when Kerry was building the rail that sells hoops and circles bent up in various radii and wall thickness etc pretty economical. I don't remember where it is on the web and it seems like it took me a while to find it but maybe Kerry still has a line on them.

On a side note I was reading an article a few years back about a well known stitcher from the later '50s and '60s that also built digger chassis and in the article it showed him with a digger frame jigged up and he was using a hot wrench on some of the bends (not the 90s I assume). But that has absolutely nothing to do with the thread I just wanted to get it out of my head. LOL

@dreracecar later on this winter I am going to be building a 6 point for my sedan I may want to pick your brain when I get closer if you don't mind.

 

I had a modified stock car builder bend up my chassis. Gave him som sketches and he gave me back a bunch of bent tubing. I used 1 3/4 DOM .120 wall. Remember you age going to have to notch the ends so leave extra for notching.
We tacked the joints and then had a professional welder come and stick it together.

 

I once carved a die out of wood and then clad the outsides with steel plate. It worked OK but was a lot of effort for a one time use. It laid around for years before getting lost in a move.

 

My local muffler shop has an old heavy 'HUTH' tube bender. He's bent 1.625" and 1.75" D.O.M. tubing for me. (matched to a coat hanger wire, 'on center'.)

Dick Jones did all my heavy tube forming when I was in Campbell... ("Sweet Richard") Smart head.