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Thread: Magic bull gear pin trickery?
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19th Aug 2019, 08:03 PM #1
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
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20th Aug 2019, 02:16 AM #2
Hi Moz,
Never having seen a 260 a picture of what you are up against would be of interest !Best Regards:
Baron J.
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20th Aug 2019, 07:57 PM #3
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 Note that the bullgear pin you see here is the short, broken pin I have, inserted into the bull gear and withdrawn all the way out to the housing to demonstrate that, even with the nose broken off, I have to wiggle like mad to get the bull pin in/out.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
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20th Aug 2019, 08:39 PM #4Most Valued Member
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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.
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20th Aug 2019, 08:55 PM #5
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
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21st Aug 2019, 12:54 AM #6Mechanical Butcher
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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.
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21st Aug 2019, 06:52 AM #7
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.
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21st Aug 2019, 08:43 AM #8Mechanical Butcher
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Headstock drawing
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21st Aug 2019, 07:38 PM #9
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
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22nd Aug 2019, 08:00 PM #10Most Valued Member
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Haven't checked my spare Hercus pins but a Sheraton pin I removed today was hardened.
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22nd Aug 2019, 09:53 PM #11
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23rd Aug 2019, 07:30 AM #12
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.
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23rd Aug 2019, 08:54 AM #13Most Valued Member
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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?
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24th Aug 2019, 01:24 PM #14
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
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24th Aug 2019, 08:03 PM #15
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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