DIY muffler

[imdying]

I'm not totally against a sandwich contruction either... it's pretty easy to get some say 1mm alloy sheet, roll it into the shape I want, and then cover that in carbon... less carbon required in that case, just using it to add strength. Not sure about the dissimilar expansion rates though :/

[geoffm]

Still after comments...

Packing? Where would I get glass pack suitable for one? Or could I used fibreglass chopped strand? Or get some fibreglass cloth and 'loosen it up' (tear it apart some) before packing the muffler?

I used layers of chopped strand and mat, wrapped tight around the core. Use packing tape to pull it tight so you can slide it in.
Geoff

[imdying]

Cheers for the reply mate

[moT]

just do it man make it. my muffler is diy and its fine, just gut out ur old factory one it means they cant fail you on ur warrents because its a factory exhaust

[imdying]

Sadly going back to the standard muffler on my bike is completely impossible. I don't have the factory headers in one piece anymore for starters :/

Going to visit a man who makes mufflers in his spare time tomorrow, he's done some pretty nice stainless work in the past, so I'll have chat with him... would like to learn more about carbon for mufflers though still.

[moT]

good on ya

[Thenaughtebucket]

Hey,

Freakshows brother here,

There could be a few issues with making an aluminium(al) can, i presume you would just make the cylindrical part of al and add stainless end caps to it, in which case there can be issues with electrolysis between dissimilar metals, and basically the al will corrode, there are ways to slow it down with basically a sealant between the joining surfaces, but when you rivet it together, it makes this a bit of a waste of time.

the other thing would be the different rates of expansion that each metal has, but i don't think it would be that bad.
But to be honest, i luv making stuff out of carbon so i wouldn't even bother with the al one.

The only major hurdle with making a can out of carbon is finding some high temperature resin, i have seen a home made one that was made with just run of the mill epoxy resin, and it pretty much shat itself.
any ideas at what sorta temp the can gets up to, if so, theres sum guys at a company called "Adhesive Technologies" in Auckland, that are gurus on resin.

As for some of your other questions,

Making a tube bag for inside the can is pretty straight forward, just need some "tacky tape" and some vacuum bad and just fold it back on itself. here are sum manufacturing pics, the steering wheel at the bottom was made using some pretty small tube bag, http://www.fsae.co.nz/nav/buildpic.htm

Do you have a vacuum pump?
Corner radius, if you have a vacuum pump, then you can often get the carbon to bend around sum pretty tight radii, and it can depend on what weight carbon you an get, 200g is pretty sweet to work with.
3 layers of 200g cloth would be more than strong/stiff enough, and you can basically layer it all up at once and then vacuum bag it,

Do you have a spare can that you can take a mold off?

[Thenaughtebucket]

forgot to read the second page of ya thread.. ohwell good luck.

[imdying]

Yeah, have a vac pump, was thinking 155gm twill.

The current stainless one is about 50-30 degrees on the outside... no idea how to measure the temp of the inside of it.

[Teflon]

If you use the right grade ali it should be fine.

316 stainless is the material i would use to build a end can.

[Teflon]

These are the bits that interest me the most. Stainless has proven to warp just a little more than I'd like, when welding large flat sections. I do have an alternative design in stainless which has less of those large flat sections and more curves, which should mitigate that somewhat, but still investigating my options

You can minimize distortion by clamping Ali to the job, this sucks heat out of the stainless. Dressing the weld with a hammer and dolly removes tension..

It really depends on what you doing.. but prestressing before welding helps. Air, water can be used to take heat out of the material, alternate welds, bracing the job before welding.. any gaps in your joints will increase distortion..

[imdying]

Yeah, 316 is what has been suggested to me... the current one is either 304 or 316, but I'm not sure which.

[classic zed]

Hey,

Freakshows brother here,

There could be a few issues with making an aluminium(al) can, i presume you would just make the cylindrical part of al and add stainless end caps to it, in which case there can be issues with electrolysis between dissimilar metals, and basically the al will corrode, there are ways to slow it down with basically a sealant between the joining surfaces, but when you rivet it together, it makes this a bit of a waste of time.

the other thing would be the different rates of expansion that each metal has, but i don't think it would be that bad.
But to be honest, i luv making stuff out of carbon so i wouldn't even bother with the al one.

The only major hurdle with making a can out of carbon is finding some high temperature resin, i have seen a home made one that was made with just run of the mill epoxy resin, and it pretty much shat itself.
any ideas at what sorta temp the can gets up to, if so, theres sum guys at a company called "Adhesive Technologies" in Auckland, that are gurus on resin.

As for some of your other questions,

Making a tube bag for inside the can is pretty straight forward, just need some "tacky tape" and some vacuum bad and just fold it back on itself. here are sum manufacturing pics, the steering wheel at the bottom was made using some pretty small tube bag, http://www.fsae.co.nz/nav/buildpic.htm

Do you have a vacuum pump?
Corner radius, if you have a vacuum pump, then you can often get the carbon to bend around sum pretty tight radii, and it can depend on what weight carbon you an get, 200g is pretty sweet to work with.
3 layers of 200g cloth would be more than strong/stiff enough, and you can basically layer it all up at once and then vacuum bag it,

Do you have a spare can that you can take a mold off?

Just a quick note to say that there is no such thing as a Vacuum pump, a vacuum is nothing therefore you cant pump it.
You can however exhaust the air inside something thus creating a vacuum.
So the pump is actually an exhaust pump

aahh I used to have hours of fun discussing this point with my lecturers

[imdying]

It's a vacuum pump. That it pumps air is neither here nor there, the end result is a vacuum. A bicycle tyre pump doesn't pump bicycle tyres...

[vifferman]

Just a quick note on CF cans: litre v-twins tend to be rather hard on CF cans, shaking them to bits fairly rapidly, apparently because of the exhaust pulses. Doesn't mean you can't make them out of CF, just that you'll need to make them rather sturdy.