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Thread: Bull pin blues - opinions, help?
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18th Aug 2019, 02:05 PM #1
Bull pin blues - opinions, help?
Hi folks.
I am loving my ex-school 260ATM and until recently, I believed that its scars from school abuse were limited to a banged-up tailstock quill and a couple damaged chuck adjustment screws...
...but now I think there's more. I've been cutting threads lately and want to move slowly, but I can't engage the back gears. When I withdraw the bullgear pin, the cone pulleys remain locked to the bull gear. There's a tiny bit of back-and-forth slop, but nothing I can do will free one from the other, despite the bullgear pin being withdrawn as far as I can get it.
Now, if pull the retaining spring out of the way and push the pin back in until it just begins to protrude into the gap the spring normally sits in, I can just see the face of the pin's end...and it appears to be fractured. So my questions to you:
1) Are broken bullgear pins something that happens? Is the nose of my bullgear pin stuck in my cone pulley, locking together the bullgear and pulleys?
2) If so...how do I fix it? Will I need to disassemble the whole spindle and then replace the pin with a new one?
Any tips and advice greatly appreciated!
Cheers,
Moz
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18th Aug 2019, 06:32 PM #2
Hi Moz,
I think you have answered your own question. Its likely that the end of the pin has been sheared off and is jammed in the recess. You could try and turn the gear so that the hole with the pin in it is facing down and tap the gear with a copper hammer and see if gravity will cause it to fall out.Best Regards:
Baron J.
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18th Aug 2019, 07:50 PM #3
Thanks Baron, appreciate your suggestion.
Yeah...problem is, the cone pulley and bull gear are still 'locked together', it seems by the broken off nose of the bull gear pin stuck in the cone pulley hole. I can't pull the broken off bull gear pin out to expose the hole, so I can't access what's left of it. Something of a quandary.
Staring, scratching head. All further suggestions very welcome!
Moz
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18th Aug 2019, 08:30 PM #4Mechanical Butcher
- Join Date
- Oct 2004
- Location
- Southern Highlands NSW
- Posts
- 1,898
On South Bend, Boxford, Hercus etc type lathes, the bull gear engagement pin goes in sideways, so gravity won't help dislodge it.
I just tried to remove it from my ATM, but the headstock housing prevents it from being able to be pulled all the way out.
Maybe it would if it were broken, but then you'd still have to install a new one.
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18th Aug 2019, 08:41 PM #5
Update - problem solved!
By squinting, sticking my tongue out the corner of my mouth and poking with a sewing needle at the barely visible broken nose of the bullgear pin as it sat in its cone gear hidey-hole...I realised that the broken bit was rotating quite freely in its recess. As the wise Baron J. had implied.
(While common sense decrees that a pin designed to be inserted and withdrawn from a hole by hand would be need to be a comparatively loose fit rather than a tight, interference fit, decades of trying to remove stuck, broken-off things from holes has conditioned me to expect the broken bit to be VERY stuck in its hole. My mistake.)
So I stuck a tiny neodymium magnet to the end of an aluminium Tig rod using hot glue, and 2 minutes later I managed to pull the stub out of its hole. Success!
I now have access to back gears, and once I buy a new bull gear pin, I'll have a fully functional lathe again, high speeds and low.
Thanks again to Baron J. for jumping in with his wisdom. This forum is endlessly helpful.
Moz
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18th Aug 2019, 09:04 PM #6Philomath in training
- Join Date
- Oct 2011
- Location
- Norwood-ish, Adelaide
- Age
- 59
- Posts
- 6,562
By all means buy one if that is the way that you want to go, but if you can't get one, happy to make one for you if you have the bits to copy.
Michael
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18th Aug 2019, 09:18 PM #7
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