Keyhole in tacks

admin

I am welding 6" pipe coupons, 1/8 6010 at 75 amps 6 g position down hill. I have a keyhole at the end of my tacks. The problem is the one on top, I start out on the tack, roll past the keyhole, step ahead then back but the keyhole just blows out and I'm done. On the opposite side with no keyhole the root goes in fine. Is there a way to close the keyhole when putting in a tack?  Or some way to get the keyhole closed quick so the root weld won't drop out?
Reply:Don't step so far over the keyhole. Keep the arc a little closer to the tack until it fuses.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:I wonder if the keyhole at the end of your tack is bigger than it should be? You could try tacking at a lower amp setting, or laying the rod angle down at the end of the tack. Both of those things should make the keyhole smaller.The worst thing I can think of happening is if everything I ever welded instantly became UNWELDED
Reply:A keyhole at the end of your tack is a good thing, if there is not I would be looking inside and wondering if I got all the way in there. If your keyhole is too big, there are things you can do. Turn down the machine, but 75 amps is already pretty low for 1/8 5p. Thats where I normally set it for a big gap, but then again I run uphill ASME code..try turning it down 5 amps, also try whipping out longer to give the puddle a chance to cool.
Reply:speed up about a half inch before you end the tack. less heat makes a smaller hole.