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Cutting holes?

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  • Cutting holes?

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Size:  61.7 KB 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?
    Last edited by d6joe; 03-12-2013, 09:31 PM.

  • #2
    Fastest way is most likely the right size torch tip (#2). If you don't get it preheated enough it will pierce about halfway through as you described. Sometimes I will preheat from both sides before trying to pierce a hole in thick plate.

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    • #3
      I would have just welded it on, The problem with torching the hole makes it suseptable to tearing at one of your holes because its not a smooth hole.

      I'm not a machine shop and certainly not a cutting expert, They might make a high quality annular cutter that goes into a Mag Drill that might cut through it.

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      • #4
        I agree with the holes weakening it. But I most likely also would have burned them in. Judging by the photos a 60" wide excavator bucket with no shanks/teeth is in light duty application. Loading gravel/product, digging in sand or dredging silt so in this application I think it would be fine. Only the OP or equipment owner could tell us though.

        I would also assume that the owner wanted a quick fix instead of replacing the edge.
        Last edited by MMW; 03-13-2013, 07:10 AM.

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        • #5
          That cutting edge is designed to be cut off and a new one welded on. With the nuts on the top side of the plow bolts like you have and poor sized holes I doubt that you will ever keep that thing tight.

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          • #6
            Originally posted by oldtimer View Post
            That cutting edge is designed to be cut off and a new one welded on. With the nuts on the top side of the plow bolts like you have and poor sized holes I doubt that you will ever keep that thing tight.
            he will have to tack weld the nuts to be safe.

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            • #7
              I would have welded it too,remember when you do cut/pierce a hole with O/A as mentioned preheat it but also to back off with your tip a little just as you start to peirce.If you do decide to weld it make sure you get the paint off and I would use 7018 SMAW or wire .045 min. dia. but pre heat and weld it solid front back and sides.These are easy to torch/air arc off it when the time comes for that.

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              • #8
                That is just the "ditch cleaning" bucket for my 200 size trac hoe. I wanted the double thickness as it does hit a few rocks, and I felt it was a built a bit thin for that width. The new edge is a CAT one, about 1 1/4 thick and 12" deep, it is made for a dozer blade, and the old edge is 1" thick. got it cleaned up today and tightened the bolts to about 500 ft/lbs. I have a digging bucket with teeth on it that gets all the rough work when digging, removing trees, using the thumb. I plan to check the bolts to make sure they stay tight, but most of the use will be in sod, sand, and silt getting ditch bottoms back on to grade. I was thinking that welding would require that both edges be pre heated and slowly cooled to not take the hardenes out of the metal. Thanks for the reply's.

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                • #9
                  BD1, Old timer is right about the bolts loosening, Tacking them wont help, They wear down into the hole because of a bad fit, Its not because the nuts back off.

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                  • #10
                    Ended up I was real happy with the fit on 7 of the 10 bolts, if they do loosen up, might have to touch up the holes with some weld or beat some steel bushing in to tighten up the 3 I am not real happy with. This bucket only gets about 20 hrs a year, so it should be easy to keep an eye on. The 30" digging bucket gets the crap beat out of it, so I should be ok.

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                    • #11
                      I would have put the good ole mag drill with an annular cutter on it, and been done with it. I have 2 in my shop, they are great tools when used properly. I have cut thousands of holes in 1" plate and never had any issues...

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                      • #12
                        Originally posted by aaronobrien View Post
                        I would have put the good ole mag drill with an annular cutter on it, and been done with it. I have 2 in my shop, they are great tools when used properly. I have cut thousands of holes in 1" plate and never had any issues...
                        But have you cut a cutting edge with them?

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                        • #13
                          Cutting holes?

                          Hougan Drill, is this really a question? Invest in your tools if you want to do good, fast work.

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                          • #14
                            Originally posted by d6joe View Post
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Size:  61.7 KB 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?
                            As a retired Heavy Equipment operator, I'm a little confused about your question regarding the old cutting edge. I'm guessing that you're talking about the bucket edge being worn due to not replacing the cutting edge before it wore past the bucket. From the picture, the bucket has really been worn down and should have been replaced long ago. I don't think there's too much you can do at this point. You can try building up the bucket edge but that's a lot of work. Hopefully, you won't snap the new cutting edge when someone gets into something solid with it, such as concrete. They're not supposed to be sticking out that far and as such, are much more likely to snap upon load.

                            Anyway, in regards to the holes, the ones I've seen done are done by a torch. With the right torch they can be cut so good that they almost look drilled. I hope some of this was helpful...

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