Pipe Bending Formula - Notch and Braze

Have you considered packing the pipe with sand and then bending it. It has been many years but I saw a machine shop in West Miami FL bend 2 inch stainless into a 180 degree curve of about 6 to 10 inch radius without crimping or crushing. They packed the tube with damp sand and sealed the ends. Someone may have better instructions as I said it has been at least 30 years since I saw it done.

Good Luck

G'day, I don't like the idea of "damp" sand as I think you'll have too much pressure build up. I was always taught to use "dry" sand, plug the ends, heat the outside of the tube (outside of the resulting bend) to a cherry red and bend a small amount at a time. I warn people though, it takes a lot of skill and a lot a oxy/acetalene gas.

I think dj95401 was referring to a mitre cut of 38 degrees, ie., two cuts of 19 degrees.

Royce

You can bet it is working very well

G'morning there Royce, How goes it down under? And your right about the damp sand, it could be a real "Blast" in the neighborhood!! But with the sand method it still requires the minimum bend radius of =>5x's the OD of the pipe. Some where in my achieves, I have have the formula in my notes from when in was in A&P school, some 30yrs ago. Anyhow, I thank you for your commits and suggestions. I was hoping not to have to dig through the dust. Have a good day my friend, Dan

Thanks for the suggestion, I've used the sand method before, but it has to be dry sand and is generally use for bends with a radius of 5x=> the OD of the tube. I had the formula when i was in A&P school 30yrs ago and it's been that long ago since I worked on a fabric airplane. Thanks for the suggestion anyhow. dj

I Fear to tread among the well versed engineers, but I was sanding the bumps off of my credit card on the internet and stumbled across a web site that made me make a purchase to alieve my future pain. it was http://www.icengineworks.com. They have a very clever idea to assit in the layout of these type of bends. I have fought with these types of probelems for a long time. If you won't spring for the price, give me a call and `i will try to do a markup of your problem and see what happens.

Best of luck

elrod

Hey Elrod, I checked out "icengineworks.com", I like their concept and approach to the problems with tuned and balanced headers. If I had more than 4 tubes to bend or building custom headers I would invest in their products. I used a formula for notching and forming airframe tubes 30yrs ago when I was going to school for my A&P license and haven't worked on a fabric airplane since. The formula as I remember is something like double the desired angle and stop drill the "mitered cut". The stop drill should be 2x the wall thickness. But it still causes wrinkles. Any suggestions I greatly appreciate them. dj

make it out of brass

You say you need to lay out (cut) a notch, then braze it. Then you say you need to bend it. Which is it?

Since you are looking for the formulas for bending tube this link should help. http://webtools.delmarlearning.com/sample_chapters/04614_ch26_p100-104.pdf

If you are attempting to make an intake manifold, flow characteristics in the product are of paraount importance. You want to bend the tube rather than crimp or cut and braze it.

I would suggest that you visit a muffler installation shop that has a computer controlled bending machine to make the new tailpipes.

They will have difficulty working with short lengths, but you can solder extensions which can be steel to save money. If they can do it at all, the quality of the result will be best with this technique.

And nothing says that their bending machine can't be combined with the sealed tube of sand trick.