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  1. #1
    Join Date
    Sep 2005
    Location
    northern NJ
    Posts
    1,794

    Default Broken/stuck bolt

    Had a job this week to remove a broken bolt. 3/4-10 x 4.5" long bolt, about 2.25" of thread in a blind hole snapped off just below the surface. The bolt is one of four that hold a pillow block bearing for the disc on a track chipper.

    No way to weld something on to the bolt unless we disassembled the chipper to remove the disc so I drilled. First a small pilot at 1/4". The problem was from the top of the pillow block to the mounting pad was 2 5/16" but I was just able to grip the end of the bit to get almost through it. Once I got to a 3/8" bit I was able to drill all the way through the bolt. Then to 1/2" bit, luckily I was able to drill through the bottom plate too so it was no longer a blind hole. I figured I would drill up from the bottom with a 9/16" bit & it would catch & spin out the top. No such luck. I tried heating what was left of the bolt but no luck either. Drilled it to 21/32" which is the tap drill size & re tapped it very slowly.

    Very limited working area but finally got it. I did recommend at one point to just drill it clean through at 3/4" & put a bolt & nut as it would be cheaper but customer said to keep trying to remove it.

    First pic is the work area. Second pic is the pillow block. Third pic is the hole. I know it looks off but just the angle of the pic. Fourth & fifth pic is where the hole came through. I crawled in to drill up from here.
    0821031122.jpg0821031121a.jpg0821031121.jpg0821031122a.jpg0821031122b.jpg
    Last edited by MMW; 08-22-2013 at 07:16 PM.
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  2. #2
    Join Date
    Apr 2012
    Location
    Western Pa.
    Posts
    190

    Default Broken/stuck bolt

    I did the exact same Repair 2-month ago. On a loader, only difference was after I got drilled through I was able to put a bolt through and weld on back side. Twisted a bolt off two times still wouldn't come out. Had to drill & tap out as u did.
    I hate them. It's a lot of work for one bolt.
    Owner was same wanted it saved at any cost.

  3. #3
    Join Date
    Aug 2007
    Posts
    712

    Default

    MMW,
    Great work as usual!!!! That is a great deal of labor for one bolt. Is there anyway to prevent that type of failure?
    Thanks,
    Nick

  4. #4

    Default Broken/stuck bolt

    Neversiese / anti seise on the threads

  5. #5
    Join Date
    Aug 2004
    Location
    Milan Michigan
    Posts
    1,633

    Default

    I would have suspended the shaft with my crane, removed the 3 bolts, removed the guard, slide the bearing off, weld a nut over the broken bolt, removed the stud and reinstall the bearing with new bolts.

    If you dont have a crane you need to do it the way you did it.

    Regards.

  6. #6
    Join Date
    Dec 2012
    Location
    Front Royal, Va
    Posts
    64

    Default

    MMW, i have drilled a lot of bolts (different application though) like you just have and the problem i have is when i center punch a start spot it ends up not being centered well enough and when i get to the last drill bit the threads have been wiped on one side. Re-taping has always worked well but sure is frustrating. Looks like you did a sound job on a very important and dangerous piece of equipment. I too am a Never Seize nut. I use it on everything i can.............
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    and 4 dogs to supervise me

  7. #7
    Join Date
    Apr 2009
    Location
    Oswego IL
    Posts
    568

    Default broken bolt...

    Next time you have a larger bolt, the bigger the bettar, try this. Take the 3/4 bolt you just did, drill a centered hole finish with 3/8 bit, try not to completely drill through, now weld the hole closed. This will shrink the bolt, and the weld heat will help to loosen the bolt. Be careful welding with flux wire as it is difficult to drill, best is standard mig wire. I have yet to have a bolt which has not come off this way.
    Kevin
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  8. #8
    Join Date
    Mar 2006
    Posts
    10

    Default another bit:

    Quote Originally Posted by Tryagn5 View Post
    Next time you have a larger bolt, the bigger the bettar, try this. Take the 3/4 bolt you just did, drill a centered hole finish with 3/8 bit, try not to completely drill through, now weld the hole closed. This will shrink the bolt, and the weld heat will help to loosen the bolt. Be careful welding with flux wire as it is difficult to drill, best is standard mig wire. I have yet to have a bolt which has not come off this way.
    Kevin
    While you are going through this process, just for kicks, drill it with a left-twist drill bit. I bought some when I had a chance, just for this problem. Sometimes, I get lucky. Not always.
    Check out survivalblog.com, and Fredsm14stocks.com

  9. #9

    Default

    Have frequently used Tryagn5s method, even on broken studs as small as 7/16".
    Keep some 14 gauge (2mm) rods for this purpose . Always try to run at least one
    bead along the drill hole first. Have had a high success rate with this method, as stated before the bigger the stud the easier it is.
    Last edited by R W; 12-13-2013 at 01:09 AM.

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