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Bore weld a cast excavator boom end

Discussion in 'Shop Talk' started by Volvomad, Feb 12, 2018.

  1. Volvomad

    Volvomad Well-Known Member

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    What is the most best way to repair worn out pin bosses made of cast something or other on the far end of an Ex 200-5 boom . My dipper has been getting wigglier year on year but and I had it on my to do list but now it has cracked outside the locating pin holes .
    I asked on the forum before about expander pins and the responses were mostly negative .
    Can I bore ,weld and rebore ?
    I dont think there is enough material to bore and sleeve .
    Should I fabricate a complete new boom end in steel ?
    DSCF0007.JPG DSCF0008.JPG
     
  2. funwithfuel

    funwithfuel Senior Member

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    Weld and bore. Just try and get factory dimensions. Also, find a constant to measure to. Otherwise you could wind up with a cattywampus bore. Thats a technical term btw lol.
    Those cracks appear perpendicular to pin locating holes. Were you using your bucket for a hammer ? Its not a long reach, is it?
     
  3. Volvomad

    Volvomad Well-Known Member

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    Thanks funwithfuel . Yes the cracks are outside the locating pin . It has a standard dipper but has placed a lot or rock armour up to 7 ton with a bucket , not a grab so it has had a tough time .
    I have line bored twice in my life , both with homemade devices . I have carefully read as much as I could find here on this subject .
    What do you mean by finding a constant to measure to ?
    Is ER70S 1mm or 1.2mm wire suitable ? It is hard to get much else around here .
    Is heat from continous welding a problem with so little parent material at 1 side of the bore ?
     
  4. funwithfuel

    funwithfuel Senior Member

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    I would contract an experienced vendor. The guy I use locally has done just about everything. He has a dedicated wire feed that has a very tight angled head for welding the perimeter of the bore continuously. Using the same bearings, he then bores the hole to spec. All i can remember was that the wire was a low hydrogen . But again, cast is not an issue if the right filler material is used.
    I don't personally perform this work, so I cannot speak from experience. My experience is that it can be done, very well, and with trusted reliability.
    The constant, that is a point that is undisturbed , equal on both sides and "true." That is the point all measuring must be made from. The last thing you would want to do is center up your boring bar 2-3* off center of boom. Then you would need spherical bearings instead of bushings in your dipper cylinder eye. You'd also dig goofy. Don't want that.
     
    digger doug likes this.
  5. Volvomad

    Volvomad Well-Known Member

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    I dont spend much time on the seat so when I do ,my digging is abit goofy anyway . As for experience , the boring jobs I got professionaly done in the past were very dissapointing . It is just my mindset ,not quiet a god complex (yet) ,but if you want a job done right them where possible ,just do it yourself .
     
  6. ETER

    ETER Well-Known Member

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    Your wire type and size would be fine (I have been using .030" up to 3" holes +/-), would not be worried about heat so much even if your welding by hand (small wire, lower heat and you can always walk away for a few minutes for a soda-pop if you think it's getting too warm:))
    I think you will know alot more about how your are going to fix it when it's dis-assembled, de-greased and the cracks are properly chased / ground out...would also be wondering how the pin bore is in the stick?
    Regards, Bob
     
  7. Volvomad

    Volvomad Well-Known Member

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    Thanks Bob . That sounds encouraging . I am going to have a stab at putting the welder spinning if I get a chance . I have a few weeks work ahead to get other stuff finished and out of the shop before I can bring in this one . I just like to plan ahead , not that I can ever stick to the plan .
     
  8. dabsfabs

    dabsfabs Well-Known Member

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    What machine manufacture. Ex probably Hitachi.

    Do a few of the of them over the year just weld it with A18 1.00mm wire argon/co2 mix of gas will give low hydrogen wld deposit.

    They are just a cast steel and weld prefectly fine. Renew the float colar and should be all fine once bored.
     
  9. Volvomad

    Volvomad Well-Known Member

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    Thanks dabsfabs . I will have a look for A18 .
     
  10. Volvomad

    Volvomad Well-Known Member

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    Didnt know I was using A18 all the time . I just look for ER70S -6 but it is the same thing .I think .