To go along with the previous post that I made in this thread, I have included another sketch to illustrate a slightly different application of this method. Most of the time where this would be used there is not a need for a "backer" or a "dolly", but when the time comes to employ this you'll likely be able to determine whether that is applicable or not. Best regards, Allan
I might add, that when you are doing welding/fitting of sheetmetal items with corners as shown in the preceeding example that it is often a good idea, after tacking, to do your internal fillet welds first and then grind the tacks out so that you can have a smooth and uninterrupted bead on the outside corner portion of your weld outs.
If you are not doing internal fillets it is still a good idea to carefully remove some of the weld material from the tacks before welding over the top of the particular seam. Best regards, Allan