Technical Roll bar 12" Radius

Using Speedway Motors 1-3/4"o.d. 73050 tubing & a borrowed Harbor Freight hydraulic type bender with the nearest 1-1/2" anvil in place to make a couple of 12" radius 90-degree bends was a complete failure as it kinked in the center & dimpled on both the left & right rollers. Used it early on to fab a front push bar using 1" black pipe & got great results producing (4) 6" or so radius 90-degree bends. I thought the larger tubing would be a snap with the larger radius & I know a ton of video's are out there, some of which I've since reviewed. thus far the sand fill & 1" increment bends or combination of both seem to be the way to go. I may fab a couple of saddle type inserts to prevent the dimpling at the rollers, if need be, although the incremental bending may resolve that issue. Years ago, I made a body roller using 1-1/4" black pipe bent around a 36" wagon wheel that worked out well & still in use. Appreciate any tips & or ideas. Ron

 

Really ? Not gonna happen !
1-1/2" anvil trying to bend 1-3/4" tube ? NOT...a good combination.
That's why 1-3/4" anvils are made.

Mike

 

First, you're using a pipe bender on tubing, you really need a tubing bender. Second, you're using a 1.5" die on 1.75" tubing.

If you don't want to buy a tubing bender, find a local shop to do the bending for you, it's cheap.

I have 1", 1.5", and 1.625" dies for my tubing bender, and a recently needed to make 2 bends in some 1.75" tubing. The dies are $160/ea, but a local off road shop only charged me $20/bend. If I was doing more bends in 1.75", I'd just buy a new die for it.

 

The 1-1/2" die seats the 1-3/4" quite well, perhaps the lack of harbor freight tolerances, no 1-3/4" is readily available so might toy with it, not sure if a 2" would be any better. And yeah ! I'm definitely a hard head when it comes to farming it out even when time is money, but I do value the input. Ron

 

Even though the tubing seats well in the wrong dies, you have seen the results. I'd be looking for the correct dies.

 

It sounds to me like you are attempting use a HF "Pipe" bender to bend tubing. Can you be a little clearer regarding the bender please?

Does it look like this?


I bought an identical style bender (to the one pictured above) many years ago and it kinked the tubing. It was suggested to me that I fill the tube with sand and cap it with expanding "frost" plugs to prevent the tube from kinking. That method did not solve my problem. The tubing still kinked. I then bought an actual "tube" bender from JD2 like the one pictured below and am now able to bend tubing without kinks.

Having been through this, it is my belief that you are wasting your time if the bender you have access to is the style in my first pic. As others have stated, find someone with a real bender.

 

I would be asking my friends involved in circle track racing as to who in the area is set up to bend tubing for roll cages. I used to live a couple of miles from a wrecking yard that built a ton of circle car chassis in their shop. There was always a frame on the jig having a cage built anytime you stopped at the shop and they gave me great deals on parts out of the wrecking yard.

 

I tried using sand in some exhaust pipe and didn't have much luck. Later I saw that someone said they used wet sand and then tamped it, but I never tried that. I also read somewhere about a guy sealing both ends of a pipe and having a pipe fitting in one end. He poured water in the pipe/tube(?) till it was full and screwed the plug in place. Seemed to be a much better idea than the sand thing.......but again, I haven't tried it myself. I do agree that you need a die that fits the pipe/tube size you are trying to bend.

 

Remember you are talking the difference between tube and pipe. 1.5" pipe is an ID measurement, 1.75" tubing is an OD measurement. So yes the 1.5" pipe die does seem to fit, not perfect but close. The problem is the difference between a pipe bender and a tubing bender. Watch some videos of a tubing bender and you will see the difference.

 

borntoloze, that top photo is exactly what I'm using & agree from online testimonials that have had varied degrees of success, I too now realize I had the (L)&(R) rollers too close & may have had better results moved farther outboard to relax the bending radius. It now becomes a matter of economics unless some scrape tubing is available, at $3 per foot & a minimum 2- or 3-foot chunk for new material for merely sacrifice can squelch an objective in short order. Incidentally the cage tubing/pipe is .104 wall

 

Pipe and tubing don't have the same OD or ID, so often a bender shoe for one size of pipe might work or a smaller size pipe shoe might fit a larger size of tubing.
All that aside, the HF benders are nearly worthless to do more than very slight bends without kinking. Even marking out 1" marks and moving the tubing before it kinks wont ever get a very tight 90. I've built firewall to frame supports using my HF bender by doing short multiple bends, but a bend needed for a rollbar isn't ever going to happen with the HF bender.

 

I have had success using floor grout mix. Cap on end with a slug of steel tacked on.
Fill. Tamp. Repeat. Then cap that end.

 

For what it's worth, before I had my tubing bender, I had one of those HF Pipe Kinkers. I experimented with it and was able to produce a decent bend in tubing without kinking the tube, but it did waste a lot of the tubing outside of the bends and it ovaled the tubing a bit. I would take 1.25" die, make a bend with 1.25" pipe, then slice the bent section of pipe in half along the radius. Then take the 1" tubing I needed to bend and slip the sliced 1.25" pipe under it like a saddle. Lube it up real good with grease, and proceed to bend. It made the bends decent for the motorcycle stuff I was doing, but after doing all of that to produce an "ok" bend, the time and effort and cleanup wasn't worth it for me. I had more success using the HF Pipe Bender to re-arch leaf springs than to bend pipe and tubing. The Affordable Bender is a major upgrade for someone like me who only needs to bend a few times a year and is on a budget, so that's what I use now. I gave the HF Pipe Bender to a friend.

 

My HF bender, like pictured above, works great on pipe, but kinks conduit. Even when I have a “close” fit in the die.

 

How to make a Pipe Bomb. ^^^^

Do NOT use water, or wet sand. BAD idea.
Water turns to steam when heated, and expands 1000%.
Use DRY sand, cap one end, fill and cap. Then heat the outside of the bend.

 

Compression bender, some people refer to them as "Kinkers".

 

I used a similar pipe bender to the HF unit. Made a test bend with the 1.75 roll bar tubing and realized that it wasn't going to work, sand fill wasn't going to work [never has in the past] as long tube for roll bar man hoop. Difference in tube od is .150, so shim each side of shoe with .075 sheet metal or close, .060 minimum at tangeint piont [at least] of 1.750 tube. Pic is what I bent.

 

I calculated that it requires a 30" chunk of tubing for a 12" radius 90 degree bend to index both rollers set at the 1-1/2" axis. ($3 X 2.5' = $7.50) might give it a try, my avatar deserves it, much like Tom Secora's Omaha fielded 34 Bonniville example, I chased this car around for several years, need to get it done.

 

Nice shoe box & handsome bars, a matter of personal opinion of course but a bit of padding on the nearby uprights might be advisable. The 1-3/4" tubing is of course a snugger fit in the 1-1/2" die than the 1-1/2" pipe it was designed to fit but did consider shimming, will approach with caution, & consider saddles where the rollers rest. Thanks, Ron

 

There's four types of benders and three types of pipe/tubing. You have to have the right bender for what you're bending.

The three pipe sizes are heavy wall, thin wall, and tubing. To throw one more turd into the stew, for their 'nominal' size, each one is different. Heavy/thin wall are 'trade sizes' and the size refers to the ID, the OD for each 'size' is different. Tubing uses the actual OD. Trade sizes are 1/2, 3/4, 1, 1 1/4, 1 1/2, 2, then up in 1/2" increments to 4". There is no 1 3/4" trade size.

The HF bender is a heavy-wall pipe bender, and the shoe design is a 'one-shot'. There is also a segment-type bender (the 'shoe' is about a quarter as long as a one-shot) where you make multiple small bends (5 degrees or less) spaced apart until you get the desired bend. You can also do this with a one-shot shoe if you need a larger radius than what the shoe has.

Thin wall and tubing benders are related, but because of the 'trade size' vs actual size can't be interchanged. The primary difference is 'followers' are used to support one or both sides of the tubing to prevent kinking/collapse. Thin wall uses one follower, tubing benders use one on each side of the shoe. I wouldn't recommend bending heavy wall in one of these, you can damage the bender/shoes.

It's critical that you have the right shoe for what you're bending especially with thin wall/tubing. Loose/tight fit of the shoe and/or supports to the thin wall/tubing will give you kinks and collapsed bends in trying to go much more than about 3 degrees per shot every time. Even with heavy wall, going more than 3 degrees for each shot will give you a 'lumpy' bend, more small bends looks better.

When I first got in the electrical trade, I thought 'Great, I can build my own exhaust'. Nope, won't work with a 'trade size' bender. You must have a dedicated tubing bender.

 

Thanks Crazy Steve, appreciate the whys & wherefores of the trade, much to be considered for what might seem rudimentary to simply bending some pipe or tubing without a kink, we're never too old to pick up a tip or basic knowledge of the trade for sure, & it's always invaluable to watch an electrician as an example, sparingly using a tape measure or folding ruler to make all the right bends & offsets when routing conduit. Thanks, Ron

 

Thanks for the Shoebox like. My pipe bender has saddles [which slide some] in place of rollers, so yes would recommend more spread out support at rollers.

 

I'll note that there's math formulas for figuring out bends. Generally only used for heavy wall bending, but can be useful for thinwall/tubing to determine back-to-back bends or developed lengths. There can be a bit of art involved also. The one thing that surprised me is that 'springback' can change according the ambient temps, sometimes by a lot.

 

As has been said before you have the wrong bender. There is a reason why tubing benders are more expensive, the tubing sort of gets drawn over the dies creating a smooth radius. My Greenly dies and shoes were about $200.00 a set.

Pat

 

Ron, when I built the cage for my avatar car I used 1 5/8" structural handrail tubing with .134" wall. The Harbor Freight bender like you have bent every piece without kinking. The wall thickness is a big deal with a bender designed for pipe. I may have used the 1 1/4" die but don't remember.

 

Thanks 1934 coupe, & I concur with bender choices, were I to tackle another such project it may well be in the cards for a better bender if only I were a young gun again .......I'll more than likely be paying a visit to a local muffler shop I've heard tell has appropriate equipment.... but not until I give it a try & convince myself to farm it out. Thanks, Ron

 

One thing I've noticed, (not sure all tube benders do this) and built my homemade one to do is actually "pull" the tube around the bend.

Pipe benders most seem to be "static" as in the pipe doesn't move on the bend, you push the center of were you want it to bend and the sides move to allow the bend.

My homemade tubing bender works great and the first thing I noticed was the fact that the tubing benders "pulled" the tubing around the bending die so that was the starting point on designing mine.....

...

 

Thanks, chicken that's a right pronto looking 'T' coupe I'm assuming, never thought of handrail although I have used the vertical stiles for fabrication before.

 

People have talked about filling pipe with various materials to aid in bending. At work they used Zerabin (sp) making master pipes, in production the benders had internal mandrels that would keep the pipes [tube] from kinking. Up to 2-1/2 od ss .049 wall, around 2-1/2" id radius.. Now anyone can buy Zerabin melts in boiling water, maybe $$, lead would probably work. Some one mentioned water and capping the ends. I would not think (?) much help unless you could put the pipe in the freezer, ice would probably do well. I bent small 5/8 OD SS tube .049 wall with couple/three piecs of plastic with grooves milled with a 5/8ths ball mill in a press arranged like in a HF bender. Did not fill with anything, ID radius about 1-1/2". Door handles. Can see drivers door through pass 1/4 window and pass door at right of pic. Max bend at ends aprox 90°.

 

I use a hydraulic conduit bender for 1 3/4 tubing with .095 wall thickness. Works great, but as @lostone said, it pulls the tubing around the shoe.