Thanks Cactus, I think I'm on board with what you guys are saying. Drop the hand and your essentially preheating your land, little bit longer arc on the leading edge and could open things up, raise your hand and your gonna be fighting a slag pool as your trying to go up. I'm guessing that raising your hand could lead to incomplete penetration on the root?
Most every person I have ever worked with on OR LH when they "get it" they all say "That's it?"
Standing back I can see the rod angle better and when I see the hand drop, the sound changes, you see the panic weave, then they pull out. All you have to do is lift your hand.
When that keyhole appears, you don't have long to close up the arc or the land starts melting ahead of the weld pool.
One thing I have seen is welders practicing who want to use sch 40 or standard wall for OR LH. Thin wall is just too hard with open root low hydrogen. Some guys when they go from the thinner wall to sch 80, one practice coupon and they have it.
Years ago I oversaw a OR LH qualification procedure using 3/8 plate. The bead was put in with 3/32 with 1/8 fill and cap. I saw a really good welder almost come to tears trying to figure the heat out. He was a crackerjack welder that before that week was a ceder post to crack of dawn welder. We went through over a dozen coupons trying to figure out how to make this work. Once he got the gap, land and heat right it was easy! The trick was a real wide land land, low and slow. If the land was 3/32 you had to be too cold. Could never seem to get the heat where it would deposit without blowing out the land and undercutting. When we put on a 1/8 land with the root opening where a 3/32 would rattle but a 1/8 would not fit the bead would go in without blowing out. The 3/32 stuck to the land, cut the shoulder of the face of the land and stacked. It was a beautiful thing. But you could not move the electrode in any direction but up. The welder had to concentrate on starting the arc and letting it go. We learned the sound it made when it was going in and like putting in a bead on pipe, if the sound was right the bead was right.
We tried a 1/8 electrode, but that was a wreck!
Testing welders was a rodeo. Trying to get through the little darlins mind to have the land that wide was difficult. But again, when they had the gap, land and heat right and they concentrated on keeping the rod parallel to the grove got the "That's it?"
Have never used OR LH on that thin of plate since.
I have only worked with two welders that could not get the OR. Some catch on in two coupons some take up to five.
Forum
