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Gotta make this exhaust part

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TFF

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Apr 28, 2010
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The high end custom header people should be able to do anything. Ever seen a bundle of snakes Indy exhaust?
 

rv7charlie

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Nov 17, 2014
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Jackson
That's what I was thinking, as well. A computerized bender can make just about any shape you need, up to the length of the raw stock.
 

Tiger Tim

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Thunder Bay
I’m pretty impressed by that ‘heat-and-go-for-it’ approach. From other videos (all Japanese) it looks like they pack the tube with sand, clamp an end in a fixture and go to town with the torch. I’m sure there’s quite a knack to it beyond that but I wonder just how much scrap I’d really make before I got it.

Anyone here ever bend thin wall stainless like that? I’d be interested in talking to you if you have.
 

Chilton

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Jun 28, 2014
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Jersey, channel islands
I spoke yesterday to a friend who has done this, he said he drew the curve onto a block of wood and routed out the shape, then stamped the part out using a screw press to apply the pressure. The pipe is shaped such that only one form is needed so not too bad to make.

Another friend made a similar bend in a bigger pipe for a Merlin engine car, he found that the pipe needed to be filled with sand packed tight for any method, and the best results came with the packed tube heated with a torch and held in clamps, long overhang to grip and bend very slowly.
The suggestion is that a minimum of six hands is available.
 

BrianW

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Jul 2, 2018
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Altus SW Oklahoma
That was my best uneducated guess but all I’m getting from shops that roll tubing every day is that it can’t be done with thin wall. I don’t doubt you for a second but it sounds like I’ll have to learn enough about it to be able to do it’s myself if need be.
About bending stainless thin-wall tube. I found this do-it-yourself version had an interesting lesson. If the internal bullet is not well-positioned, the interior of the bend concertinas.
Not that I am proposing D-I-Y You can see that the device is not trivial.

 

pictsidhe

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Jul 15, 2014
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I've also used a blowtorch and sand on pipe. The trick is in packing the sand very tight. After trashing a few pieces, I worked out I needed to weld one end shut, fill and tamp with rod and hammer. Then weld a nut in the open end and keep screwing more sand in. Tedious, it amazing how much extra you can get in. If it isn't packed hard, it will kink. More recently, I bent some sch40 PVC into some snakes with tight 2x diameter bends. I made a wooden jig with shaped formers. I had several different ones so made up universal jiggery. Packed and capped the pipes and put them in the oven. They come out as very hot noodles. Takes a while to warm through. Worked brilliantly, they almost looked mandrel bent.
 

blane.c

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Jun 27, 2015
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capital district NY
If you are willing to weld the straight sections to the bends? You could make female molds of each half of each curve and press a piece of sheetmetal into each mold using a block of rubber then weld the mating halves together.
 

Geraldc

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Nov 12, 2011
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nz
could make female molds of each half of each curve and press a piece of sheetmetal into each mold using a block of rubber then weld the mating halves together.
I have made female molds out of hardwood and used a pneumatic hammer or a riveting hammer with a rounded nylon end.
I think some car restorers call this flowforming.
 

Geraldc

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Nov 12, 2011
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nz
That would have been done unpacked. Steel bends nicely when hot. There is a knack to getting the radius where you want it. That guy has done that many times.
I did my Norton pipes that way.On my own with heat and a vice.
 
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