Bending 2" diameter pipe/tubing

I’m looking to bend some roughly 2" diameter steel pipe/tubing (can be thin walled) into a 180 degree bend such that when I’m done, I can get a half circle of diameter 18" or so (to the outside). I need 4 pieces to come out as close as possible. I can’t have it kinked or severely deformed. I can pay a shop to do it or I can invest in a tubing bender as long as it isn’t too expensive. I’m thinking I need to get these 4 pieces bent for under $200. Should I have it done somwhere? Where? Would this be something a muffler/exhaust shop could do maybe? Or should I buy a bender? What kind? Would this do it? http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=32888 If it takes like 8 tries to get 4 like ones, that is okay but I will need 4 like ones in the end.

Or better yet, is there something that exists already (tube or solid actually) round that is already approximately that diameter material and that radius of bend that is a half circle or more?

Exhaust shop.

Their labour costs will be far less than $200 for the time that it takes to bend those on a hydraulic tubing bender.

Edit: How much deformation can you deal with, and is this structural? Go to a precision fabricator (e.g. of heat exchangers or storage tanks), if you need something with guaranteed structural properties.

I would be tempted to stop by a muffler shop or two and ask. I bet they could bend it for you for not much $. Ask if they have a scrap bin you could dig through and see if there is some mis-bends in there you could snag and cut as needed.

And they’ll be able to do 180 degrees and get 4 pieces the same? And by chance do you know how much a straight exhaust pipe (like 2") costs per foot?

It is going to be a small roller coaster type thing. It will carry two “cars” each only 40 lbs max. The “cars” will need to be able to roll without a problem (I’ve already devised a way to get them around the tight radius) but no actual people will be riding on it.

Here’s the idea:
Wheels: http://team696.org/images/roller_coaster.jpg
Track: http://team696.org/images/track_shape.JPG (nothing too fancy)

Interestingly, the roller coaster pictured – Lethal Weapon Pursuit at Warner Bros. Movie World – was disassembled. It was a piece of crap. :slight_smile:

If they have a simple manual hydraulic bender like the one that you linked to, they would typically bend it using several partial passes of another radius, and work their way up to the full shape. You’d have to consult them to see how accurately they can do this, with their equipment. If they have a computerized hydraulic bender (a large exhaust shop would likely have one), they should be able to do it in one or two passes.

I don’t know the price for exhaust tubing off hand, but I’d be concerned about it properly supporting a 40 pound car, especially considering the forces as the car rounds the curve at speed. Can you consider mild steel or 4140 structural tubing (more for the wall thickness, than for any special material properties)?

Two things:

  1. Remeber pipe and tube have different O.D.s so if you use exhaust “pipes” its actually tubing.

  2. Would electrical conduit serve your purpose? It’s easy to bend and any electrical supply house should be able to provide what you need. Plus its galvanized so unless your welding that is usually a bonus.

Sandrag,
Muffler shops bend pipe but it changes the diameter to prevent cracking the side wall. Electricians bend pipe all the time. Any larger contractor should be able to make it happen in just a few minutes. I would ask around at your school, they liklely have a contractor they normally do business with who would do the job.
The bender you linked to is generally not designed to perform 180 degree bends. Most often these are used for 90 and 45.

Conduit and pipe benders (like the one you linked) would do the job, but you’ll be limited to their bend radii, which are pretty much standard. These mostly use a fixed bending shoe, proportional to the conduit diameter - I think code requires at least 6 X conduit dia… For a “custom” radius, you’d need a different kind of machine. You might find a custom motorcycle shop which could do a custom bend for you.

In any case, at $75 the Harbor Freight machine may not be a bad route if it will do the job. You might pay that much in labor to have tubes bent for you.

Conduit will work. It will be welded together, but we can grind off the galvanizing first and/or weld outdoors. It is possible that instead of a continuous 180 degree bend, that I can join two 90 degreee sections.

Today I’m going to go take a look at 90 degree EMT conduit sweep elbows, that harbor freight bender, and some exhaust shops.

Took a look at the HF bender. It’s die is for 90 degrees. Looks like a decent unit, but repeatability may be a problem. Took a look at 1 1/2" EMT conduit sweep elbows. Liked em so much I bought a couple (only $5 each). The radius is pretty much perfect, and conduit will be nice because it won’t rust and it doesn’t cost too much. So, I think that’s what I’m going to do. Cut and weld together two 90 degree 1 1/2 inch EMT sweep elbows. Seems like the easiest way out.

BTW, 1 1/2 EMT conduit is closer to 1 3/4 OD if anyone was wondering.

You can also buy pre-bent tubing: http://www.woolfaircraft.com/elbow.htm from aircraft & speed/racing shops

Here are some from summit racing. Some are close to what you want.

http://store.summitracing.com/egnsearch.asp?N=4294820497+4294864608+4294864568+115&Nao=0#rstop