DIY muffler

[imdying]

Built a muffler, out of 304 stainless, it work quite well. Want to build another, out of aluminum, any reason why I shouldn't?

It's under the seat, so things like heat radiation etc are important, weight, less so. For what it's worth, the stainless one under the seat has caused no issues with heat at all.

Other alternatives are welcome, but carbon is out, and I have been unable to find anyone to weld titanium for me.

Ideally, I want a list of the pros and cons of stainless vs aluminum, from people who know about mufflers and/or metals.

[degrom]

If they can weld aluminum they can weld titanium. Same process...

[Crisis management]

It is certainly possible, it's only metal after all....

Aluminium will expand faster than steel or stainless which may be an issue at the junction to the exhaust pipe however the greatest difference is that aluminium is softer and weaker than stainless so you will need to either design carefully or use heavier section material to gain the neccessary strength. This will be most obvious on mounting points as the loads will need to be spread over a greater area to avoid cracking the aluminium sheet (body of the muffler)

I tend to think aluminium is a bit overrated as a fabrication medium due to this weakness but its lightness, maleability and pleasant finish are advantages.

Give it a shot, should be interesting.....

Don't bloody radial mount it tho!

[imdying]

If they can weld aluminum they can weld titanium. Same process...

Please tell me more?! I was under the impression it needed some sort of chamber to weld it in? I wonder who has Ti stock?

maleability and pleasant finish are advantages.

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

Heh, it already is radially mounted somewhat

[Babelfish]

Whats the prob with carbon out of interest?

Radial mounting? I had a girl that liked that once...but in engineering terms how does this work on exhausts?

[imdying]

Carbon, cost mostly. One day though. That and the twin would blow it up, unless I used a whole heap of it.

[Pumba]

So you just got it al finished andlooking good to rip it apart and start again.

[imdying]

So you just got it al finished andlooking good to rip it apart and start again.

It's evolution baby

[imdying]

Another question... as I understand it, you can only anodize parts made from billet into nice colours. Something to do with the composition of the metal taking to the dyes, where cast doesn't. As I undestand it, sheet metal will anodize nice colours also.

What would happen if you were to weld up a box from sheet and anodize it? Would it all go a nice colour, except for the welds?

/edit: It would appear that die cast alloy has a lot of silicon in it, making it nearly impossible to anodize.

[Crisis management]

Bloody spank, he's fucked up all the user names now.....

Not an expert on anodising but a quick Google shows anodised welded aluminium is ok...

I've certainly seen anodised cast aluminium so a closer look into that might be needed....it melts at @ 700 so not beyond the capabilities of a good gas axe? Lost wax process anyone?

[degrom]

Please tell me more?! I was under the impression it needed some sort of chamber to weld it in? I wonder who has Ti stock?

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

Heh, it already is radially mounted somewhat

Well I am busy with a Tig welding course at the moment. What I have learned is that NON FURIOUS
metals like BRASS, COPPER,ALUMINUM and TI needs AC current to weld. So if you can do the one
you should be able to do the rest.

The Tig process uses gas as a shield that prevents the metal from reacting with air(Hense your
airless environment to work in). Some gasses also work better with certain metals.

If you know a bit about electricity you will know that AC flicks polarity every few seconds.This has
a huge effect on your welding because with AC it cleans you metal and penetrates it on each cycle.

Aluminum is a funny metal to work with. It does not change colour with heat but it has a lower
melting point than steel. Aluminum is a lot like an Ogar/Onion they have layers!!! You need to
break thought the outer layer before you can start welding it. With AC Tig welding you do that with the
cleaning part of the cycle. With Mig welding you normally do it with a special flux that sit's
inside your wire. In the past they use to do it with the flame but you had to use a lot of ugly
stuff to clean it.

Anodizing is a process that takes advantage of the layers. It can harden the metal to almost 10 times
its original strength but it's only skin deep. Anodizing can only be done to Aluminum as far as I know
and it also needs to be a very clean type of aluminum. It works the same as any other plating process.
(Basacally it Uses a DC current that shocks the metal and sort of burns it into the metal)

When you colour anodize an item you basically open up its pours, add the colour and then seal it again.

TI welding supplies you should be able to get from BOC.(Or they will help you get it...)

[degrom]

Bloody spank, he's fucked up all the user names now.....

Not an expert on anodising but a quick Google shows anodised welded aluminium is ok...

I've certainly seen anodised cast aluminium so a closer look into that might be needed....it melts at @ 700 so not beyond the capabilities of a good gas axe? Lost wax process anyone?

I am sure you can anodize it... Problem is it might have stains on it.. :P

[degrom]

Another question... as I understand it, you can only anodize parts made from billet into nice colours. Something to do with the composition of the metal taking to the dyes, where cast doesn't. As I undestand it, sheet metal will anodize nice colours also.

What would happen if you were to weld up a box from sheet and anodize it? Would it all go a nice colour, except for the welds?

/edit: It would appear that die cast alloy has a lot of silicon in it, making it nearly impossible to anodize.

Depends on what you use to cast with(Old scrap or expensive stuff)... And how clean you casting environment is...

[imdying]

In other news, carbon fibre pricing:

155gm twill, $101.75 per sq/m
4L resin, $67
Vac film, $6/m
Breech unit to connect vac to, $68

/edit: Apparently the Airbus A380 has a lot to do with its unavailability at times of late.

[imdying]

Still after comments...

Has anyone built there own carbon fibre muffler? I'm thinking a combination of stainless and carbon might be ok.

If carbon isn't strong enough, I guess I can just add more layers?

Has anyone ever tried to vac bag a tube? I've a few ideas on how that might be accomplished, but would be interested in talking to those that have done it.

Anyone got an opinion on how many layers to use? 3? 5? Can you vac bag 5 something 5 layers thick? Or do you have to do each individually? Can you make the tube with one layer, and then add more after the first has cured? Or do all the layers have to be 'wet' at once to ensure adhesion between them?

Anyone got an opinion on what sort of minimum corner radius you would have to use for 3-5 layers?

What about sealing the metal ends to the carbon tube? Just use maniseal at the join, then rivet it up good?

What about what sort of rivets to use?

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?