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Old 23-07-10, 11:59
cantankrs cantankrs is offline
Alex McDougall
 
Join Date: Feb 2009
Location: Kalgoorlie, Western Australia
Posts: 200
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Hi Michael,

I agree with Matthew except I gave up on the weld spot timer as I could wing it with less hassle. And hrpearce's bigger gap sounds right too. I've just checked what controls your Mig has in your earlier pic and I see your wirefeed was at that time set higher than your voltage. At those settings I normally would be doing continuous welds. If your welder dials do equate to mine (different brand) then for tacking I set the wirefeed rate just below the voltage rate (took me ages to work this out !@#$%^&)!! So set on '4' for voltage and just below 4 for wirefeed for single spot tacks. That has the heat high and the wirefeed slow to really fuse the tack with low buildup and maybe a little bulge on the back - but no gap still remaining at that spot. If you see gap still at the back then you're being too gentle and you have to find a closer compromise between tacking and melting through. If you're grinding flush (maybe you're removing a little too much I think and concaving the panel which means more body filler or spray putty) then in my opinion you want the back of your welds to be slightly bulged to provide strength. For thin stuff I never continuous welded longer than about 3/8" or I'd burn thru, or not penetrate, so good spotting was the go. And tacking at opposite places like tightening wheel nuts helps you keep progressing without stopping all the time to cool it (by force or naturally) - subject to patch size like Matthew says.

Also you might be able to squeeze a slight improvement (cos your pics are great) for us out of your pics if you wirebrush the soot off first. Would make it slightly easier to see and compare the tacks.

Regards

Alex
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