As usual, I am about done with a little project, and decided to ask advice about how I should have done it. I am putting on a new cutting edge on a 60" wide trac hoe bucket. The original edge is part of the bucket, and was not drilled for a replacement edge. So making 10 1" holes in 1" thick very hard steel has been tough going. First I tried my good drill bits. I have drilled out good grade 8 bolts with these cobalt bits with not problems. They would hardly touch the hardened steel of the old cutting edge. So I put the gouging tip on the 80 amp plasma cutter. Massive blow back until I got a hole through. Not happy with what it was doing to the torch head. Tried the oxy/acetylene. First hole not too bad, it blew right through, and I made the hole to size with the plasma = I do not have a big enough oxy/acc tip to do a good job on 1" thick. Next hole the oxy/acc blew down in about a 1/2 inch and stopped. Cleaned the tip, no help. Used the plasma for the rest of the hole. I managed to get all 10 holes opened up by using combination of both units, and will trim them tomorrow to better match the new cutting edge that will be bolted under the old edge. I wonder what the machine shop would have used to punch through? Just a really big oxy/acetylene outfit? The plasma worked well once I had a small hole to start with. This is the first time I have to go through hardened (may be A/R) material that thick. As the front of the old cutting edge is rounded from wear, will welding in a bit of filler to the bottom of the old edge hold to the hardened steel? I was thinking that it should just pack with dirt and not worry about it?
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