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  1. #1
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    Default Magic bull gear pin trickery?

    Folks -

    You might have seen a recent post where I lamented that I had the nose of a broken bull gear pin stuck in my cone pulley.

    The good news is that I managed to remove it. So now I need to replace the pin with a new one.

    My question to the wise, gathered masses...has anyone ever replaced the bull gear pin on a 260 ATM without removing the spindle? Happy to dive in and remove the spindle if need be, but if anyone has any tricks and tips on how to replace the pin without doing that, that would be amazing!

    Thanks again, people.



    Moz

  2. #2
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    Hi Moz,

    Never having seen a 260 a picture of what you are up against would be of interest !
    Best Regards:
    Baron J.

  3. #3
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    Sep 2018
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    Default

    You want pics? You got 'em!

    Hopefully you can see the spindle layout and my space crisis in these. Note that the bullgear pin you see here is the short, broken pin I have, inserted into the bull gear and withdrawn all the way out to the housing to demonstrate that, even with the nose broken off, I have to wiggle like mad to get the bull pin in/out.

    There's no way that I can see that I'd be able insert/remove a whole, full-length new bullgear pin.

    It looks to me like I'll have to pull the spindle out - but happy to hear any advice to the contrary.

    Cheers,



    Moz

    Herc260 2.jpgHerc260 4.jpgHerc260 3.jpgHerc260 5.jpgHerc260 1.jpgHerc260 6.jpgHerc260 5.jpg

  4. #4
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    Default

    Unless you are able to either grind/cut a recess in the Headstock housing or drill a hole to be able to insert the pin without going into the bearing housing you will need to remove the spindle.

  5. #5
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    Default

    Quote Originally Posted by pipeclay View Post
    Unless you are able to either grind/cut a recess in the Headstock housing or drill a hole to be able to insert the pin without going into the bearing housing you will need to remove the spindle.
    Thanks pipeclay.

    Well, in that case it looks like the quest for a miracle is over and the spindle will be coming out. There's no way I'm carving up my baby to fit the new pin. I haven't had it for very long, but I'm already very fond of this little lathe so I'm certainly not inclined to start hacking into it.

    Appreciate your input.

    Cheers,



    Moz

  6. #6
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    Oct 2004
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    Default

    It might be worth trying to make a 2 part pin?
    The plunger part could be short enough to insert, have a threaded hole in it.
    The knurled part could be screwed in afterwards.
    I don't think the pin is hardened, but try a file across it.

  7. #7
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    Default

    Hi Moz,

    Thankyou for the pictures, at least I can see the problem you have ! Regretfully I don't have a solution other than to say that I agree the spindle will have to be removed to do the job properly.

    From looking at your pictures the 260 looks to be a very nice machine, certainly one that if it were mine, I would want to look after it.
    Best Regards:
    Baron J.

  8. #8
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    Default

    Headstock drawing
    Attached Images Attached Images

  9. #9
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    Sep 2018
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    Default

    Quote Originally Posted by nadroj View Post
    It might be worth trying to make a 2 part pin?
    The plunger part could be short enough to insert, have a threaded hole in it.
    The knurled part could be screwed in afterwards.
    I don't think the pin is hardened, but try a file across it.
    nadroj -

    Funny you should mention that; the same occurred to me last night as I lay awake in bed, pondering this issue. I may just give this a go. I'll post pics if I get a bullgear pin build going. Not frightened of pulling the spindle, but this lathe is nicely set up, I'd really love to leave the spindle as it is if I can.

    Baron, thanks for that. Yes, it's a sweet little lathe and I have already learned a lot on it. I'm keeping this one for life.

    Cheers,



    Moz

  10. #10
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    Default

    Haven't checked my spare Hercus pins but a Sheraton pin I removed today was hardened.

  11. #11
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    Quote Originally Posted by pipeclay View Post
    Haven't checked my spare Hercus pins but a Sheraton pin I removed today was hardened.
    Thanks pipeclay.

    Yeah, I ran a file over my broken pin and it's pretty hard. I think that the two-piece pin plan has bitten the dust and the spindle will indeed be coming out. It's all learning, right?



    Moz

  12. #12
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    Hi Moz, Guys,

    It could be too hard ! A very brittle pin would tend to break under shock loading. You might find that a pin made from say EN19 would be hard enough without being brittle. Also that pin has a groove machined in it, that would create a shear stress point.

    A bit like grinding a groove round a piece of HSS tool blank so that you can break a piece off. I doubt that you would have anything to loose making a two piece pin and trying it. The only issue that comes to mind is I wouldn't leave the threaded handle screwed into the pin whilst using the lathe in case it unscrewed itself and got into the gears.
    Best Regards:
    Baron J.

  13. #13
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    Just curious, if you try the 2 part pin how would you stop the 1st part from turning when fitting the 2nd part?

  14. #14
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    Quote Originally Posted by pipeclay View Post
    Just curious, if you try the 2 part pin how would you stop the 1st part from turning when fitting the 2nd part?
    It's a good question you ask, pipeclay. And if the answer is something along with lines of "I dunno. Maybe just add some red Loctite, spin it up finger tight and pray?" then that looks like a bodge and I'm not keen.

    I also considered milling a little spanner flat on each of the two halves, but again, not ideal.

    I have a new pin on the way from Mal. I reckon its arrival shortly will be all the catalyst I need to just tear down the spindle and do this properly.

    "Overthink things? Me?" (Yes. Definitely.)



    Moz

  15. #15
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    Hi Moz,

    Actually looking at the pictures and thinking about it some more. If there is enough clearance to insert a pin without a head on it, you could machine a pin with a circlip groove on the head end and use a flat bar to fit the groove so that it can be pulled clear.
    Best Regards:
    Baron J.

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