Thread: Choosing a mandrel tubing bender?

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I am looking into making custom exhaust systems,up to 4".I would like to do some smaller stuff like roll bars also.What brand and models do you guys use?
what would you recomend?Thanks

Exhaust tubing is too thin wall for my bender, i have an antique Hausfield I wouldn't trade for any of the new ones. If i remember right, the mandrel benders for exhaust have to have something that goes inside the pipe to keep it from collapsing...?????

Harbor Freight sells a few different exhaust pipe benders but for 3" I think they only have one. I don't have one but have used one and they do the job very well. I think they run about $100.00.

I could be wrong, but I don't think you can use the same benders for exhaust tubing (thin wall) and also dom tubing (roll bar type) We tried bending some headers in our bender that we use for the roll bar kind of stuff, and it kinked it.

We have a Pro-tool 105K and it is terrific. Bought 3 different sized mandrels with it for the most popular sizes.


Don

I'd bet u could use 1 of those if u put a peice of flex pipe inside of it to make the wall thicker, then worm it out after.

A true mandrel bender, as used by exhaust system manufacturers (not muffler shops) consists of the following: An inner radius die, that is almost a perfect "size on size" with the O.D. of the pipe being bent---the die is round, and has "half" of the pipe shape scalloped out of the outside diameter. The outside diameter of the "die" determines what the inner radius of the bend in the pipe will be. Two hydraulic "grippers" which close on the pipe on either side of the area which will be bent, and a mechanism which holds one gripper stationary, and swings the other "gripper" through an arc which will hold the pipe in contact with the "radius die".---And most important of all, a series of "slugs" which have an outside diameter slightly less than the I.D. of the pipe being formed. These "slugs" are not very long---less than an inch, and are all hooked together with a flexible spring which keeps them together. Before the bend is started, these slugs are inserted into the pipe, and positioned exactly where the bend will occur. As the pipe is bent through whatever angle is programmed into the machine mechanism, the slugs keep the inner wall of the pipe from collapsing and deforming. A flexible "pusher rod" is then inserted into one end of the pipe, and the chain of "slugs" is pushed out the other end. When I first seen one operating, I thought the slugs would all be jammed tight inside the bent pipe, but they weren't--they slid out very easily. Thes mandrel bends are beautifull, with no deformation whatever.

Thanks for clarifying Brian. I knew something was used on the inside of thin wall pipe, but have never seen the process myself.... I've tried exhaust tubing on my bender, lots of kinks....

the way i have done the big tube ex 3. 3.1/2 and 4 is to get all my tubing at the truck store that deals in truck parts .i have done many this way and cut what i need let say two45 i will buy one 90 this is sometime cheaper than two 45

I was a design engineer for Volkswagen when they had their manufacturing plant in Barrie, for 8 years. I designed a lot of prototype machinery for the production of Catalytic converters. One of our pipe suppliers in Toronto had the machinery for pipe bending, and I seen it while on a visit to his plant, looking for sources for engine "down" pipes that run from the engine "down" to the catalytic converters.

The Harbor freight model works great for pipe,black iron, galvanized, etc. I've never gotten what I would call a good bend with dom, or any other kind of tubing using it. Most commercial muffler shops have their own benders,but most I've seen decrease the inside radius as they bend.The type Don pictured I've seen used on dom and chrome-moly successfully.Hank

To go up to 4" with thin wall tubing, you are going to need to go to a mandrel type bender of substantial size . Some used ones are for sale here...
http://www.hornmachinetools.com/usedrebuilt.html
Jeff

Originally Posted by BigTruckDriver

I am looking into making custom exhaust systems,up to 4".I would like to do some smaller stuff like roll bars also.What brand and models do you guys use?
what would you recomend?Thanks

I was the Prod Mgr at a factory that made a lot of oem stuff for harley . they had a computer controlled bender thad had inner mandrals, balls connected with a Ss cable it pulled thru the tubing as it bent it . about 150 k for it .I was always told to pack the pipe with dry sand weld caps on the end and heat and bend it . I tried it once and it didn't work. I built a set of outside exhaust for the 427 Cobra that set the track record at MIS. The car owner knew the owner of the Thrush mufflers factory in detroit and he let us use his shop from 6 PM to 6 in the morning Every kind of tool to fabricate you could dream of. the easiest way without propper benders is to buy prebent turns and cut and weld

Originally Posted by DennyW

That's what I usually do myself, is get the pre-bents, and modify from there. Or, if you want one complete pipe, it's better just to find a good place, and price, and let them do it for you.

that's what I do, I got to advance auto and raid the shelves of pre bent exhaust pipe peices for what I need, slip it togther and weld up after cutting and fitting.

Not really to thrilled about Harbor Frieght stuff.I have a few things I bought there ,but it's just cheap China stuff,or looks like it at least. I am planning to invest about 6 to 10 thousand on a good machine.Used is ok also I will probably get more for my money if I go the used route.I definitely don't have 150 k to get a top notch one. From reading your replies maybe I am asking a little to much out of a bender.Maybe I will check into the pre bent stuff and get a smaller bender for roll bar type stuff.