getting motivated again. hydroforming basics and twisty pipes.

[Deleted member 12676]

I think the main advantage of hydroforming is the time savings to make a curved header section. I like to see the distinct sections in the pipe so would probably make the remaining cones the normal way and weld them all together and then to the header.

 

[HeadSmess]

have fun with that

welding 0.8 stainless is no fun, plus it cracks if its not completely immersed in argon. ie, welding in a glovebox... theres a reason i only made 1 stainless pipe, ever.

the specific alloy in use plays a part...

if he works at the laser cutters, that saves a fair wack. local company quoted me over $200 for 20 pieces in 1mm gal. me supplying metal and dxf files. real competitive over here...

it isnt as easy as it sounds "hammering to shape". sure, works if determined but its a lot of work. better to have lines etched into them for folding on, the more bends the better. you need a special panbrake but thats no major issue. way easier than trying to produce conical sections with a ring roller etc

the metal stretches and deforms and the perfect profile is no longer so perfect once joined together.

then making sure each and every weld is square and round (ha ha!), making good header joins so it doesnt vibrate to pieces, blah blah blah yarda yarda.

ive done enough to think its stupid and hydroforming is the way. or some type of spinning system, like they do trumpets etc. but the same problem arises. welding each section together. its a lot of work! (and if you get someone else to weld it up... expect around 200 or more for that little job. at least 3 hours. if theyre any good...

the pressure is well within a pressure washer with 10,000psi or so on tap.

sure, therell be some wasted bits of steel as one gets the fine details right but what jag said there was basically the procedure i was thinking of... even with variations of 5-10% from calculated... the differences should be consistent for a given material at a certain thickness at a certain pressure. not that hard to calibrate for.

im planning on getting if not a whole pipe in one go, close enough to the mark to make the one or two sectional welds a lot quicker. youll note most factory pipes are done this way, either hydroformed or stamped, and then seam welded only. very quick and cheap.

at least doing it freeform (no mold) allows for even faster simpler changes to dimensions.

you could even try making prototypes from plastic sheet or doped tissue paper and seeing how they inflate with air... possibly. worth a shot...

 

[lazylightning@mail.r]

have fun with that

welding 0.8 stainless is no fun, plus it cracks if its not completely immersed in argon. ie, welding in a glovebox... theres a reason i only made 1 stainless pipe, ever.

the specific alloy in use plays a part...
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if he works at the laser cutters, that saves a fair wack.
you could even try making prototypes from plastic sheet or doped tissue paper and seeing how they inflate with air... possibly. worth a shot...

Hi Headmess!

I made a stainless tourque pipe before and it was/is great. When riding in the winter, with all those chemicals on the road, the hot header pipe almost rusted through in a two week period once. My next header will also be made of stainless. The header will be connected to docking ports via strong springs, to both the exhaust manifold and the tourque pipe. Otherwise the excessive forces when jumping and riding bumpy roads could break the header pipe, again...
My friends friend has a laser cutter at work and does side jobs. All pieces cut cost me about $18 US, their metal (0.8mm stainless). I'm hoping everything will be okay with the welds. The main thing is to hang that pipe so that there are no stresses on it. My first pipe was welded by a magician named Nadya, at my old work. She was a 60 year old granny at the time and she has the highest rating of welding experience, went through decades of shipbuilding. Sooo... using the 0.8mm stainless steel sheet I cold forged into perfect pieces, she was able to weld the cone and belly seams and the cones and bellys together using a typical stick weld system with huge 2mm stainless electrodes. There were a few tiny holes here and there, but the JB weld helped just fine. When we were done welding it together, she smiled and told me that no other welders in Moscow could have done that for me, and that it was all because of her skill. I had no doubts. Whenever she raised hell about someone in the buying department having supplied her with electrodes that she deemed unfit, she always got things straightened out. Such welders are highly praised. After each cone and belly was done, I would clean off any metal that dripped through to the inside before joining it to the neighboring cone. She did it for free, spreading out the whole job over like two weeks, so our boss wouldn't get sore too.
This time however, I have gotten alot of my own experience in welding thin stainless sheet, using TIG. One of the most important factors I have discovered is not only the proper settings, but using a thin donor electrode. Dropping big beads from a 2mm rod screws things up in a really big way because the huge heat you need to melt and spread that fat bead is more than enough to put a hole in the thin walled stainless sheet right next to it. A 0.5mm donor rod is even good on thicker sheet. By making all the edges meet perfectly so no light gets through allows one to weld the seams without using a donor rod almost all of the time. That's how I plan to weld this one. After each tack weld is placed, the edges should be corrected so everything stays right on. After several tack welds are in place, it aint going anywhere and you can just go around and melt those edges together. There are some TIG machines at two of the shops I can go to and use the equipment and I don't have to pay anything since they owe me money =-)
Yeah, pounding those cones into perfect shape is a long and tedious process. Two or three cones a day is more than enough. No need to stress oneself. I understand that the seams will be done on a seperate day and then on another day I will weld those cones together. No need in me getting on people's nerves by sitting down on the TIG and trying to weld it all at once. Besides, once you get tired, the results of the welding can vary greatly...
I had thought about making a form for a tourque pipe from solid steel, from two peices that squeeze the metal sheet in between them using hydraulic pressure. The thing is, it should be a popluar pipe that many people need, to justify all the work in preparing such big and heavy steel molds and a hydraulic pressing setup for it.
When you mention typical pressure washer, do you mean like the small Archer models (on wheels), easily moved by one hand, or do you mean some kind of special car wash industrial unit sized thing?

 

[lazylightning@mail.r]

As you can see, I made my first torque pipe out of an old stainless vat I found laying in the garbage by my apartment building. I used an old IKEA office chair shock absorber thing as the round anvil surface for pounding and a large hammer. It looked nasty after it was first welded up, but then I cleaned it up a bit and it's just fine.

 

[lazylightning@mail.r]

Here's my new stainless steel gas tank. I made it out of scrap stainless sheets of varying thickness. The gas cap is a wonder of engineering. I made it have three levels inside. Each level connected by a small hole and with a spiral labyrinth in the first two levels. There was supposed to be a small airlock screw that I could close when I'm not riding to prevent fumes from leaking out, but I didn't get it done before my trip to Crimea last summer. So once when I had a full tank, the thing fell over on it's side in the little vacation house and since I was on the other side of the room and my hands were full, it took me a whole four seconds or so to pick the bike up off of the floor. Not even a single drop spilled out! On the road it's great, no drops come out from the bumps at all. It hold's exactly 2.0 liters.