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Old 12-10-2010, 09:41 PM   #23
devonduboy
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Join Date: May 2007
Location: cullompton devon
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Quote:
Originally Posted by redoxide View Post
Hi, back to your welding question, I see your welder is a 130, my guess is that it will be a hobby machine? If so is it fair to say that the current and wire speed adjustments are limited with rocker switches? Next my guess is you could be using CO2 as a shielding gas?

If thats the case your welding will be greatly improved with better quality gear with a greater range of current and wire speed control.

Ditch the CO2, its not the best for shielding, your better to commit to an account with a gas supplier and go for Argoshield ( BOC ) or Cougar ( air products) which are a CO2/Argon mix.

With the corect settings and the proper gas and some practice, your welding will be more consistent.

I would also agree with what wa said in a earlier post re the wire size, 0.6 wire is all you will need for panel work, 0.8 is way to thick,

Keep the gas cup close to the job to ensure that the gas does its job of sheilding the weld area, if the wire is pushing you off the job, slow the wire speed down.

Ensure that both sides of the material are cleaned and the job is propely earthed.

what m going to say next might be a bit contravercial, where mig has its place for attaching metal to metal, where it comes to bodywork O/A is much better. People seem to think that oxy acetalene causes distortion which is had to fix. Its not true for the best prt. Any welding process will cause heat in the weld area which will shrink the material along the heat affected zone. This is where it gets interesting.
If you butt weld panels together with MIG you will have to grind the weld flush, a couple of things are happenig here,
1/ your adding material in the form of weld wire to create heat and weld area.
2/ you have to grind the weld area and in doing so create more heat

The hardness of mig weld doesnt allow you to sort the shrunk area by stretching with a hammer and dolly, hence why most mig welded repairs are plastered with body filler.

O/A on the other hand doesnt require the additio of filler wire if done properly, the panels can easily be but welded edge to edge with no filler wire and therefore no aditional material is aded to the weld area.

Once the weld is complete the heat affected area can be lightly hamered and dollied to re strretch the weld area bringing it back to normal, in the process the weld bead will also be plannished out requiring no griding, so your left with a panel that needs very little final prep.

dont use overlap joints or joggled edges thats bad practice for a number of reasons . get out of the habit as soon as you can.

hope that helps, could go on but need to dash off to work ... cheers for now ..
cheers for the info mate, much appreciated.

have taken it on board
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