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  1. #1
    Join Date
    Jul 2006
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    Canberra
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    Default Ways to remove stubborn set screw in motor pulley?

    Following the stunning success of asking here how to get out a stubborn shaft key on my d-bit grinder restoration, I'm back with another pull-aparts question.

    I've got an electric motor pulley here, mounted on the motor shaft, with an M8 cup-point set-screw that will not budge. It's on my brick-saw restoration, and although the pulley has lived under a belt cover and doesn't look too bad, I think it must be a rust problem?

    There are two set-screws, one onto the shaft key, which although quite tough, still came out ok just with WD40 and an ordinary hex key wrench (on inspection, the threads are clean); and this li'l bugger that is set directly onto the shaft, which won't move at all.

    I filled it with WD40 for a week, then tried an 18V impact driver. I had it hammering away until the battery went flat. No result.

    Actually that was on the second impact bit, since the first one snapped off.

    So what next?

  2. #2
    Join Date
    Apr 2012
    Location
    Healesville
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    2,129

    Default

    Sit the flange of the pulley on something solid and put a neatly fitting punch in the hex key hole and give it a thump, with a bit of luck that will bury the point in a bit further into the shaft and loosen the screw enough to undo it ? Maybe ?
    cheers, shed

    ps. I use one of those hand held impact drivers the you crack with a hammer, speaking of which, does anyone know where to get new bits for them?

  3. #3
    Join Date
    Jan 2018
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    Aldinga Beach.
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    148

    Default

    Ebay used to list them.

  4. #4
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    Apr 2009
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    Ballina N.S.W.
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    644

    Default

    Gunnaduit,
    Maybe the set screw has been loctited, I have run into this before. I used a very fine flame on a portagas hose and heated the screw up then it came out OK.
    Bob

  5. #5
    Join Date
    Jul 2016
    Location
    Melbourne
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    35
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    Default

    I would think loctite, it is strange that there wasnt any on the other setscrew though. I have drilled a small hole through the bottom of grub screws to release their hold on the walls before (once) it was a pita but worked

  6. #6
    Join Date
    Jul 2006
    Location
    Canberra
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    288

    Default

    Yeah, the punch-and-hammer technique hasn't made any discernible difference. It's either I resuscitate the blowtorch kit (needs new gas bottle, was going to get onto that ...), or I just drill it out, get the pulley off (if that hasn't been loctited) and tap out the remains of the drilled-out set screw.

    Come to think of it acetone is a solvent for loctite isn't it? Uh, no wait, that's a question been put on Practical Machinist, the problem is the acetone can take days to work down into the thread -- suggestion was apply soldering iron to the screw -- that's quicker for me than getting onto that blowtorch kit ... I'm off to dig out the big soldering iron ...

  7. #7
    Join Date
    Jun 2007
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    sydney ( st marys )
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    Default

    What size grub screw are you attempting to remove?

  8. #8
    Join Date
    Jul 2006
    Location
    Canberra
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    Default

    Quote Originally Posted by pipeclay View Post
    What size grub screw are you attempting to remove?
    It's M8, takes a 4mm hex key.

    Anyway, the soldering iron idea was no good, the iron heated enough to smell hot dust, but wouldn't even burn a tissue. It came from my dad's tools, would've been made in the 1960s. Obviously affected by entropy.

  9. #9
    Join Date
    Apr 2012
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    Healesville
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    This is what I would try https://www.ebay.com.au/itm/Teng-15-...itleDesc=0%7C0
    Try your local repco or supercheap or even kmart, even if it doesn't get your screw loose it will be invaluable in
    the future, no workshop should be without one....

  10. #10
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    Default

    You may have to drill it out if it's that tight.
    Surprised it hasn't stripped the hex.
    Have you tried tightening it then reversing.

  11. #11
    Join Date
    Jul 2006
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    Canberra
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    Default

    Quote Originally Posted by shedhappens View Post
    This is the hand-held impact driver that you use with a hammer, that you mentioned above? Interesting, and not too pricey.

  12. #12
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    Jul 2006
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    Canberra
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    Default

    Quote Originally Posted by pipeclay View Post
    You may have to drill it out if it's that tight.
    Surprised it hasn't stripped the hex.
    Have you tried tightening it then reversing.
    Hasn't stripped the hex socket on the set-screw, but I snapped the first allen key I tried, then twisted the remaining stump of it up into a corkscrew when I tried chucking it in the 18V drill (lots of torque on those things). Tried tightening then reversing but it didn't help.

    Heat didn't do anything (though I don't have a pinpoint burner that really shoots into the screw hole, and the one I have wouldn't heat much - the pulley dissipates the heat too well). Anyway I doubt this set-screw has been loctited, if the other one on the pulley evidently had not been.

    Yes it's starting to look like drilling it out is the only way, if there's no other suggestions.

  13. #13
    Join Date
    May 2011
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    Murray Bridge S Aust.
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    If the pulley is made from Aluminium, warm it up so that it's too hot to handle, particularly around the hub area. It should expand enough to crack the screw loose. If you're needing to drill it out, use a cobalt drill bit, as by the sound of it, you haven't rounded the socket, it's a good quality grub screw, which will be HARD.
    Kryn
    To grow old is mandatory, growing up is optional.

  14. #14
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    Jul 2006
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    Canberra
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    Quote Originally Posted by KBs PensNmore View Post
    If the pulley is made from Aluminium, warm it up so that it's too hot to handle, particularly around the hub area. It should expand enough to crack the screw loose. If you're needing to drill it out, use a cobalt drill bit, as by the sound of it, you haven't rounded the socket, it's a good quality grub screw, which will be HARD.
    Kryn
    I should've mentioned, the pulley is steel. What do you think about more heat for a steel pulley?
    And thanks for the tip about a cobalt drill, yes I suppose after all I've thrown at it, it is a bit surprising I haven't stripped the hex socket.

  15. #15
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
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    Default

    Hi Guys,

    I've had similar issues with seized grub screws ! A blast with an oxy acetylene torch has worked for me a number of times. The small calor butane blow lamps don't get hot enough fast enough to expand the bulk of the pulley and crack the thread joint. Also sometimes you can get the grub screw to move by tapping the hub with a hammer whilst hot.

    The other thing to watch out for is the dimple where the grub screw dug into the shaft it will have distorted and/or raised a burr that will make a puller required to get it off. DAMHIKT I've broken a cast iron pulley in half trying to get it off the shaft, and they are not cheap.
    Best Regards:
    Baron J.

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