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Excavator pin boss replace

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  • Excavator pin boss replace

    I made this pin boss and installed it. It's a Hitachi EX270LC. It measures
    16 3/8" long and 7 5/16" outside diameter. The pin is 3.536 diameter. The boss weighs about 160 lbs. The sides of the boom were 3/4" thick and the top and bottom were 1/2". I didn't make the pin.
    Attached Files
    Zeb's Welding and Machine

  • #2
    Here's the finished and installed pictures. It is the boss that attaches the jib boom to the bucket.
    Attached Files
    Zeb's Welding and Machine

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    • #3
      Here's a pic of the entire machine. I welded it in with my Dynasty 300. This kind of stuff is what I need the Invision for.
      Attached Files
      Zeb's Welding and Machine

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      • #4
        Looks good, but I'd run a few more passes on the top and bottom of the boss to boom joints. There are incredible cantelever forces on that shoulder pin. What material did you turn the boss out of?

        Doing big stuff sure can be satisfying can't it
        hre

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        • #5
          Originally posted by Protraxrptr17
          jib boom
          Nice job there Protraxrptr17. I always like hearing the different terms for things across the country. Around here the operators call that the dipper stick

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          • #6
            up here we call it the wrist joint on the stick, the boom being the first and larger of the two.
            hre

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            • #7
              Originally posted by Coalsmoke
              the boom being the first and larger of the two.
              Naaa, that’s not a boom. Now here’s a boom. 100-tons of boom
              Attached Files

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              • #8
                ZWM -

                Nice job! Much bigger OD and the steady would have been too small

                What process & filler for the welding?
                Barry Milton
                ____________________

                HTP Invertig 201
                HTP MIG2400

                Miller Trailblazer 302, Spoolmatic 30A, Suitcase 12RC
                Clarke Hotshot

                Comment


                • #9
                  Originally posted by Coalsmoke
                  Looks good, but I'd run a few more passes on the top and bottom of the boss to boom joints. There are incredible cantelever forces on that shoulder pin. What material did you turn the boss out of?

                  Doing big stuff sure can be satisfying can't it
                  It does look like it needs a couple more passes looking at the pics. I beveled the boom to 1/8" all the way around. There's serveral passes stacked in there.

                  I love doing this big stuff. The other day I replaced the blade trunnion ball on a dozer. I wish I had taken some pics of that. I'm going to try to get in the habit of getting pics of all the big stuff.

                  I like dipperstick. Might use that

                  precisionworks,
                  I used 1/8 ER70S-2 Dynasty 300DX Tigrunner in TIG mode maxxed out at 300 amps of course.
                  Yeah, the steadyrest was pretty much maxxed out too. I had to trim the T-handles off the bottom adjusters to clear the ways.

                  Thanks for the good words. I thought it looked good.
                  Zeb's Welding and Machine

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                  • #10
                    Do you preheat huge assemblies prior to welding? I can see where 300A would be 'just enough'. That's when you wear the heavy Elk leather MIG gloves for TIG.

                    I've never done a job that size, so this question may seem dumb, but would Dualshield or a metal-cored MIG wire also be something to consider? One of my customers rebuilds coal mining equipment & they run lots of those wires. Their smallest power source is 600A
                    Barry Milton
                    ____________________

                    HTP Invertig 201
                    HTP MIG2400

                    Miller Trailblazer 302, Spoolmatic 30A, Suitcase 12RC
                    Clarke Hotshot

                    Comment


                    • #11
                      I'm guessing that it took just a little while to do it with Tig You probably found the new meaning of patience Bout that material for the boss, I'm really hoping you can tell me that it is a well hardened material, or that you put a sleeve in. Hopefully I'm not bursting your bubble. Just figured I'd mention something about it to be on the safe side.
                      hre

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                      • #12
                        Originally posted by precisionworks
                        I've never done a job that size, so this question may seem dumb, but would Dualshield or a metal-cored MIG wire also be something to consider?
                        Barry I’m thinking T and M

                        Comment


                        • #13
                          precisionworks and pilebuck,
                          Yes, that would have been a much better choice. I don't really get along good with my ancient Mega-Mig well enough for critical, heavy stuf like this. That's why I have been wanting an Invision or 350P. Stick woulds have been good for this too, but I'm not as comfortable with it as I am TIG. It takes much longer but I am 100% confident in my work when I use TIG. I also race ATV/Motocross and I handmade most of the chassis on my bike, so I put my life on my own welds. It has a really steep learning curve.

                          Coalsmoke,
                          I just forgot to add what material I used. I told my supplier the application and he recommended what he called "mechanical tubing" The center was already bored to approximately 3 inches. The stuff seems pretty hard. My cutting tools had a hard life cutting this stuff. I asked my customer if he wanted some sort of brass bushings made and pressed in, and he said that he had been that route with the original boss and they wore out so quickly he wanted to try going without them. It makes sense. He uses this thing very hard. It removes old asphault and concrete regularly. A brass bushing will just get pulverized. He keeps plenty of grease on his machines so I don't think there will be much of a problem. The main thing he wants is a tight joint with no slack.

                          As far as T and M, I warned him ahead of time that this would be an expensive piece. He said he didn't care, he just wanted it fixed right. He said, "If you want the job, take it." That's all I needed to hear.
                          Zeb's Welding and Machine

                          Comment


                          • #14
                            Originally posted by Protraxrptr17
                            I just forgot to add what material I used. I told my supplier the application and he recommended what he called "mechanical tubing" The center was already bored to approximately 3 inches. The stuff seems pretty hard. My cutting tools had a hard life cutting this stuff. I asked my customer if he wanted some sort of brass bushings made and pressed in, and he said that he had been that route with the original boss and they wore out so quickly he wanted to try going without them. It makes sense. He uses this thing very hard. It removes old asphault and concrete regularly. A brass bushing will just get pulverized. He keeps plenty of grease on his machines so I don't think there will be much of a problem. The main thing he wants is a tight joint with no slack.
                            I've never heard of brass being used, I agree it would be way to soft. From the factory application the Hitachis have a hardened sleeve, about 18-20ga thick, but if some boob gets lazy with the grease, it doesn't take long to wear out that sleave. Usually any steel in the 40-50 points of carbon range will last 5-7 years easy, and if you get up towards the 80+ points you'll be good for quite some time, providing the grease is kept up. It might be worth your while to see if you can get the exact steel specs for that stuff you got. of course, as you mentioned, if your cutting tools had a hard time getting through thise (providing they were crabide tipped) I would not worry. If standard HSS bits cut it then it might be worth looking into. Remember to not apply grease until final assembly, as this helps prevent grit from getting and staying in the bore. We usually spray it out with a cleaner first, anything that removes dirty / grit and evaporates quick will do, lightly grease pin right before installation. Good job, its nice to see people doing things right. That new boss is plenty hefty
                            hre

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                            • #15
                              Thanks for the info Coalsmoke. Most of my experience comes from logging equipment. That's why I mentioned the brass bushings. The boring bar and turning tool I used had triangular carbide inserts. That's a good idea about not applying grease before attaching the bucket. I'm sure the pin would get dropped on the ground at least once.
                              Zeb's Welding and Machine

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