Filling and drilling holes in mild steel

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I have a newbie question before I try something.I recently acquired a dethatcher that was used by a rental company and it was ridden hard and put away wet.As a result some pieces of 1/4" steel have quite wallowed oval bores.  What I would like to do is tig weld the holes shut with ER60-2 wire and redrill them.  Will the weldment be too hard to drill properly?  I have stick/TIG/Mig/oxy-fuel available to me right now.  Which is the best process?  All my hole filling up until this point as simply been fill and grind flat so I haven't drilled a weld yet.Chris
Reply:Don't think it should be a problem. The hard spots are not so much the weld it's self, but the areas out in the HAZ where the metal depending on carbon content can become tempered. With a standard drill though, likely best to compleatly fill the hole, grind flush and redrill, otherwise the drill will wonder and potentially catch. With an endmill it would be possible to drill into a partially filled hole, that way you wouldneed to do less filling, save more of the original hole edge and put less heat into the piece.Last edited by Timberwolf; 09-11-2008 at 10:09 AM.Lincoln PT185 TIGLincoln 175 MIGLincoln 240 amp AC StickLind Needle Arc plasma welderPlasma cutter, soon???
Reply:If these are also mild steel, you'll see little difference if any when drilling.  Easiest method is to back the holes with a piece of aluminum or copper, and fill with MIG.  If you can't do that, you can build it out with whatever method you like.
Reply:Originally Posted by SupeIf these are also mild steel, you'll see little difference if any when drilling.  Easiest method is to back the holes with a piece of aluminum or copper, and fill with MIG.  If you can't do that, you can build it out with whatever method you like.
Reply:Amazing, but no, it won't stick unless you start driving the arch into the backing plate, then things will get messed up. Often you can weld onto the end of a steel bolt snapped off flush in alluminium  and then screw it out like nothing. Good trick to get you out of a jam.Lincoln PT185 TIGLincoln 175 MIGLincoln 240 amp AC StickLind Needle Arc plasma welderPlasma cutter, soon???
Reply:The material is 1/4 inch thick, but what diameter holes are you talking about?Small diameter holes, fill with weld.Larger diameter holes, drill/mill oversize and plug with a chunk of the appropriate diameter bar stock.  Weld the bar stock to the parent material.  Re-drill the needed holes.  The best laid schemes ... Gang oft agley ...
Reply:Originally Posted by MoonRiseThe material is 1/4 inch thick, but what diameter holes are you talking about?Small diameter holes, fill with weld.Larger diameter holes, drill/mill oversize and plug with a chunk of the appropriate diameter bar stock.  Weld the bar stock to the parent material.  Re-drill the needed holes.
Reply:post us a picture..
Reply:When plug welding holes in steel, a method for this situation that would work better than just putting in a filler and swirling is to use backing on one side. Next make the hole slightly oval on the other side. This will allow for the use of stringers, making fusion and shrinkage issues less of a factor. Fill flush. Now grind other side to clean metal making the area slightly oval and fill with stringers. grind flush as needed.