Aluminium welding

[steven_191]

I have a small arc welder and mig welder. I read that you can use a mig welder to do ally but tig is easier and neater.

I'm not planning on doing anything major. Just tacking bits in place before I get a pro to go over it properly.

I need to try to make up some engine mounts and tack them in place. The trouble being, my frame isn't clean ally some will I have problems? Also can I make the mounts out of anything other than ally or will it not weld?

[ZRX61]

You have to change the gas to run aluminium wire in a mig, & most use a spool gun because the wire hangs up in the liner. The cost of setting it up just for a few tack welds just isn't worth the expense.
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[steven_191]

The cost of gas and wire?

[ZRX61]

[kestrel]

ZRX61 is bang on the money. Aluminium can be welded with a MIG set but it's very hit and miss unless you are using a high end machine. Welding aluminium with a standard machine requires a good quality wire feed setup, too little pressure on the feed rolls and the wire won't feed, too much pressure and the wire will 'birds nest', DIY sets don't generally have good enough wire feeds. The best way to handle wire feed on aluminium is a spool gun which carries a small spool of wire on the torch, eliminating the problem of having to push a very soft aluminium wire through the full length of the torch liner.
As ZRX61 said, you will have to change the torch liner to plastic or teflon to prevent contamination of the filler wire from the standard steel liner, special contact tips are usually used which allow for the expansion of the wire, although you can sometimes get away with using an over sized tip. Shielding gas for Ali is either pure argon or alushield.
Mig sets used for aluminium also require a higher output to cope with the thermal conductivity of aluminium.

[steven_191]

If I can't tack weld it I'll have to find a way of getting the mounts positioned and hope whoever welds it does it in the right place.

[jimbothe]

Make them up and use a very small piece of 'quick steel' to hold it where you want it. Make sure it stays under the mount and doesn't squeeze out. The welder chap will be able to weld all the way round the mount and the quick steel won't get in the way.

If you're not sure what I mean it's this stuff.

https://www.pistonart.uk.com/acatalog/Quick_Steel.html

Still holding my saab turbo sump together after a year when I .....
...... ahem ...... went way too fast over a speed bump
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[Ichy]

I'm involved in building prototype car bodies in various materials. There is nothing that holds a couple of panels together better than a screw.
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[kestrel]