http://www.kiwisteel.co.nz/services-...-rolled-steel/Originally Posted by Grumph
Anorak
http://www.kiwisteel.co.nz/services-...-rolled-steel/
Kinky is using a feather. Perverted is using the whole chicken
Pretengineer
Interesting info there Husa. I saw in the pitlane thread about the use of regular cold rolled steel so that is what I will start with. I have a sheet of 1mm turning up on Monday.
The tool I am going to lack in the process is a swaging jenny to do pre bend the edges to get a nice butt weld. I might look at making a specific one just for doing this job as it should be pretty easy to make. Failing that I might just use a hammer and beat it over a former.
I'm just about to start getting the dimensions together from Frits' pipe formula, however I am not sure what percentage I should add to my measured RWHP to get my crank HP. Are there any common factors that people use to assume this?
Forum whore
I thought 10% was the go. So plus 10% of 85hp for the 300.
Forum whore
'Failing that I might just use a hammer and beat it over a former.'
No need to get too flash. The above method will do just fine. Use a plastic or similar faced hammer.
Anorak
...................................
Kinky is using a feather. Perverted is using the whole chicken
Anorak
I have PM''ed Howard asking him to contribute here.
Here is a few more posts off pitlane.
I have been around long enough to see a pipe failure or two as well. Thin pipes (under .035") tend to have shorter life spans. Most of the failures I have seen were due to vibration. Cracks appear within inches of the cylinder or where the tail pipe welds on. Also the weld-on fittings for temperature sensors seem to be a source for cracks to develop on thin wall pipes. Going to .040 or thicker reduces the likelyhood of pipe failures.I manufacture hydroformed pipes and I agree with Jan that 1mm or 19 gage cold rolled steel works best. Going thinner especially on bigger engines that tend to vibrate more will result in a shorter life span for pipes and they will crack. Going to thicker metal adds weight but does make the pipe more durable. Thicker pipes need more warm-up time to stabilize the temperature and come up to full revs. Thin pipes do tend to heat up an cool faster which is good for a drag racer but not for a track engine.
Kinky is using a feather. Perverted is using the whole chicken
Moped rider
No idea if they still do but when I was working there 10 years ago there was more than one package of deep drawing steel sent form Dunedin to Auckland where it ended up as exhausts, it was only used in the ovens.
Low personal B.M.E.P.
Re the Kiwisteel link...I did speak to them, I actually found someone who'd been there long enough to remember drawing/forming steel sheet.
I was assured that, no, sir we haven't carried any of that for years now....BUT, if you cared to order at least a ton....
I spoke to every steel importer i could find. Most had never heard of it.......I spoke to every company i could find left in the SI doing presswork. All told me that they weren't doing enough deep pressing to justify getting any in.
Just because they have it listed on their website, it doesn't follow that they'll carry it - or the yoof who answer the phones will know anything about it...
Anorak
No doubt they too have a minimum order I just googled it to see what it was.
I would say find someone or something that has deep pressings ovens esp trays I guess is one maybe fridges.
Kinky is using a feather. Perverted is using the whole chicken
Low personal B.M.E.P.
I met a guy who teaches welding at Otago Polytech. His family had a presswork company and he reckoned most of the deep drawing steel came in through Dunedin. He asked around, I asked around, and it's stopped coming in....
Moped rider
The other one I can think of is SAFA tool boxes but havent seen them for years either. It not just the lack of materials that is a problem (in the wider scheme of things), there is a lack of technical skills left in the country too. I was designing some stamped/pressed stuff awhile ago but didnt find anyone in NZ to get advice from and even had another company ask us for help....
Anorak
I'm picking most of those space heater and so forth are no longer made on Dunedin?
Kinky is using a feather. Perverted is using the whole chicken
Pretengineer
Right so I sat down and had a go at the FOS exhaust concept.
I think i've got it right, the only variable i'm not 100% sure on is the speed of sound. I pick that this will be the speed of sound at the exhaust operating temperature? After a quick google I found that most suggested that I use 550m/s
I'm open to any peer review on the numbers to make sure I haven't made a hash of them.
Anorak
There is a site I will post in a few seconds that does this as a spreadsheet based on the basic Frits formula.
http://www.kiwibiker.co.nz/forums/sh...post1130535174
The site the spreadsheet is in the post
http://www.underdogsracing.com/fospipe/
the default used is 550.
they also have a software program for doing the cones as per the tygr or as Wob does them
https://www.conelayout.com/ that's not free though
Kinky is using a feather. Perverted is using the whole chicken
L-Plate Rider
Seems like that somebody had time to make this thread first.
But, I hope I won´t be banned because of this (maybe too long?) report. At first I´m going to introduce the designing principles I have, and after that the manufacturing itself.
The design:
First off, I´ll start with this Excel sheet that uses Blair´s design principles: http://www.mediafire.com/download/t8...rExhaustII.xls
That´s the most common design tool used in Finland, it´s been made by this mysterious Finnish two stroke guru "Sarvi-Perkele". After the basic values have been inserted into the sheet, the measures are copyed into MOTA file of the motor being builded. First simulation is run through, and with "gray matter" simulator (aka. the brains) the dimensions of the pipe are altered into better direction. With Suzuki EPO type engines the transfer timing is usually quite high, so coarse modifications to measures given by the sheet are somewhat easy to deduce without MOTA´s help. MOTA gives different dynamic pressure/velocity/purity etc. graphs, which assist the brain-simulator´s functioning. After figuring out some (many) different exhaust pipe measures to copyed files, the simulation continues. The best simulations are selected, graphs are expounded, measures are modified with reasoning and brain-simulation and new files are made, with altered dimensions. This algorithm goes on and on until the prediction of MOTA doesn´t get any better with changed measures. This takes about 100...200 seperate MOTA files, which are simulated and expounded one by one. This takes huge amounts of time and coffee.
So, you have the measures, now you´ll have to choose whether to make pipe out of cones or to hydroform it. If you decide to take cones, there is not much to talk about, when it comes to the drawing. "Cone layout" is the best option at that case. You can also save the Cone layout´s spreaded cones into .dxf form and open them as a group in AutoCAD etc. It will help you save a lot of paper when you can put many cones onto one paper.The angles and lenghts are easy to measure and determine with bikes frame and bended steel wire etc. You can also make projection of bike´s sideview onto cardboar etc, to ease up the designing.
If you go for hydroforming, things get more complicated. You´ll have to determine the "wireframe route" of the pipe, use steel wire etc. Then you must decrease all the angles just the "right" amount, this is the part where you need the experience and gut feeling. I´d say take 20 degrees off, if the turn is 90 degrees. Pipe´s radius, "expansion angle" and the diameter vs. lenght will affect the need of loosening the bendings. A good rule is that "you can easily make loose turn into tighter, but not the opposite way". Note that the errors you make, tend to have cumulative effects on the pipe´s fitting.
Now you can start drawing, either by hand or with some CAD softwares. I used to draw by hands, but now I´m into CAD since I can use those softwares. The only rules I can give to you are these:
1) Multiply all diameters with PII/2.
2) Be accurate, errors can be cumulative.
3) Measure lenghts with "bending" measures (ie. plastic ruler), since you tend to get big errors if you try to measure lenght of and arc with non bending measure.
4) When drawing small diameters, add some exrta, when large diameters, take some off. Experience helps in this case.
5) Whenever possible, take advantage of using circles etc. simple geometrical forms.
6) BE PRECISE AND AVOID ANY SHARP EDGES!
And some pictures to help understanding:
Radius changing principle in hydroforming
Left: Hand drawn hydroforming "middleline" with loosened corners, assisting picture and assistant. Right: Middleline & assisting picture=cutting template.
Some old hand drawn assisting pictures (so called straight pipe with PII/2*diameter):
The cone way via Cone layout & CAD:
And the CAD way of making hydroforming templates (this is quite tricky for a novice):
The manufacturing:
Via Cones (& universal cutting experience): Not much to explain, cut the spreaded cones on the paper on the lines. Glue those templates onto sheet metal with paper glue (0,75mm sheet metal is my favourite!) and start cutting with air nibbler/sheet metal cutting shears/sheet metal cutters/plasma cutter/angle grinder/fret saw. You can also cut the pieces a bit oversize and grind them with bench grinder etc. into accurate dimensions, it´s actually quite quick. When cutting whit sheet metal scissors bevare of cutting in such way, that the jaws get together all the way, it will make a nasty twist on the sheet being cutted. Cut a little, move the jaws, cut a little... Makes much cleaner cutting surfaces. My favourite method is to first cut the raw shapes with air nibbler, leaving about 2-3mm of "extra metal" around the template. After that it is easy to cut the final shape with sheet metal scissors, since the cutting of narrow slice won´t warp the final template at all. Btw. it´s a good idea to write an identification number on each cone...
Next thing is to remove the glued papers and start rolling the cones. If you want, you can do some grinding on the edges of the templates before it. The easiest way is to put pipes of different diameters into vise, and bend the cones with bare hands against them, until they´re all round and beautiful. This is the part where you realize, that YOU SHOULD NOT MAKE TOO LONG CONES. Long cones are really hard to get bent, and they require hammering, sweat and tears of masochism.
Btw. I made this DIY cone roller, works just fine.
After the cones are finished, start tacking them into right positions one after another. If you are uncertain of you welding skills, I recommend that you won´t tack the whole pipe into one solid piece. Make it in three....four seperate pieces, and you are still able to grind off any burn throughs inside the pipe, if such would occur during welding. You can also use duct tape etc to hold the cones on line when tacking the pieces.
This is the same pipe, as above in section "The cone way via Cona layout & CAD:
And this is the aluminium version of it (not welded yet, material is ½ hard 0,70mm aluminium sheet):
Via hydroforming: I like to use regular 0,75mm thick sheet metal, it´s cheap. When it comes to welding, I use my old Kemppi MAG welder with 0,80mm wire and CO2 as shielding gas. I also have a TIG, mut here in Finland the argon is so insanely expensive, that I won´t use it on exhaust pipes. The refill of 20 litres and 200Bar container costs at worse roughly 180 Euros. I have made one pipe with TIG, and the hydroforming was ridiculously easy...
But, let´s get into it. First you take the paper template and glue it onto the sheet metal (beware of making too much waste pieces!). Now you´ll have to add some more material at both ends, since else it wouldn´t form nicely and there would not be enough space for the filling adapter and air extractor.
Cut it. I like my own style, explained in the cone section.
Copy the other half and cut. Pictures positioned on the right are from other pipe projects... Grind edges if necessary.
Bend the edges. Don´t bend too much, 60 deg. is good, avoid sharp edges. If you bend too much, you´ll end up with poor fitting when the halves must be alinged, since you can´t hammer them so well together. I have these DIY bending pliers, I recommend them tho anyone who´s into hydroforming.
This is the fun part! It always seems like that: "These won´t fit at all!". Relax and position the halves onto each other as good as you can. Tack them together on few points. Take time to think, hammer the edges carefully together and tack. If the edges overlap, pull them apart with screwdriver and hammer them into line. Grind the tacks as much as you can, since they´re masters of causing wrinkles, remove all welding splatters. You should end up with something like this (last picture of another pipe):
Time to weld it up! If you can, use TIG or gas welder. If you can´t you should do MIG/MAG tacks one after another, unless you are a good welder. But by my experiense is that the line of tacks tends to act nicer when hydroforming. They won´t also leak so easily. Beware of making too high beams, they´ll cause wrinkles. Drill some 5mm holes on the each ends of the pipe. Weld nut onto the other end, and filling adapter on the another end. (Two last pictures of other pipes.)
Give some softening heat treatment to the hard MAG welds. Aluminium melting furnance works just fine for this step...
Connect the pipe to pressure washer with something. I use this High-End DIY billet connector, "push&turn!".
Let the water flow into the pipe, make sure there is no bolt attached to the nut at the other end of the pipe. Turn the pipe into different directions, until you are sure that there is no air at all in the pipe (air comes out from the nut). Install bolt to the nut and pull the trigger. If you are going to hydroform the pipe in one piece, put the middle section in a strong vise, between thick planks and secure with something VERY durable rope etc. Start hydroforming. When the header is almost formed, remove the pipe from the vise and continue forming. Use ball end hammer to get rid of those wrinkles. The hammering might take a lot of time and patience, but keep hammering until you´re just too tired. The pipe may "explode" quite a few times during hydroforming, so safety goggles should be used (it won´t be too dangerous, if there is no air in the pipe). When it explodes, weld it together, fill the pipe with water ONLY and repeat until you are too tired to weld it together anymore.
Cut the pipe´s ends in right lenght. You should end up with something like this. Again other pipes on the right...
Depending on the design, cut the pipe into sections. Weld the pieces together into right positions, add stinger, flange and attaching components. (Last moped not mine, though the pipe is made by me.)
And here are some useful tools:
And some pipes, not all though. (Most of these were lend by Finnish moped tuners, we organized this charity dyno-day to get knowledge of these pipes)
Btw. it takes about 1 day to do one hydroformed pipe. From hand drawing to first start.
PS. Sorry for my bad English!
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