Watchmaker's Lathe Overhaul (WIP)

I made this contraption to reduce the speed of the sewing machine motor to something more manageable for the 3mm shafts I need to turn down. When I took it back to the horologist for a check out he said it was still way to fast. He put a tach on it and measured it at 15,000rpm. The damn thing was advertised as 6,000 on fleabay!

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I spent several months farting around with other options and looking for another small motor for a small price. When I got out-bid on the last one I decided to see if I could go back and get the original motor working.
 
I cannot remember the exact problem with the original motor, and I cannot find a reference in my notes. The brushes were gone so the ones I sanded down from 6X6mm to 4X4mm must have been part of the problem. I had ordered some 4X4mm brushes on a slow boat from China and they did not arrive until I was in the middle of the SMM.

So in installed the "new" 4X4mm brushes and everything seems to work.

I removed the SMM motor from the mount in the previous post and screwed the K&D motor to that sliding board and there was enough adjustment available to use the existing drive belt. The K&D motor seems to be running OK but I will have to make some changes. First test was to try turning an HSS shaft and it only shaved very small pieces off the shaft. Changing pulleys to increase the turning speed seemed to help but I quickly ran out of range.

The motor was oriented the same as the SMM, which left the oiling ports for the bushings horizontal, facing forward so that oil will not weep down to the bushings. Last nite I disassembled the pulley jig from the lathe and drilled some holes to mount the K&D motor to the large base, rotated 90° so that the oil ports are vertical. Tonight I will try the various combinations of the 3 pulleys on the motor and 4 pulleys on the lathe to see if I can find an optimum speed.
 
Thanks Scott. She has been steadily declining in the last few months and the only question was "when". We visited her late July in Nashville and have an abundance of good memories.
 
Oh wow. Sorry to hear about your Mom. You'll always have the memories. Best wishes to you and your family.
 
I made this contraption to reduce the speed of the sewing machine motor to something more manageable for the 3mm shafts I need to turn down. When I took it back to the horologist for a check out he said it was still way to fast. He put a tach on it and measured it at 15,000rpm. The damn thing was advertised as 6,000 on fleabay!

View attachment 1277800

I spent several months farting around with other options and looking for another small motor for a small price. When I got out-bid on the last one I decided to see if I could go back and get the original motor working.
VFD..
 
If "VFD" means Variable Frequency Drive and not Volunteer Fire Department, this motor may be too small. What I have read about VFDs is that the motor to be controlled must be at least 1/8 HP, or 746/8=94 watts. The K&D motor is 0.35A at 120VAC, or 42 watts max (~1/18 HP). The only numbers I have are the Amps and the rpm, so I may not be computing this correctly.

I hope my math is correct.

Please let me know PDQ if you find a VFD that is PDC to LTE 1/18 HP. It would greatly simplify this task.
 
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Thank you. Near the end she would often smile, get a twinkle in her eye and say that she was "Ready to go Home". She was always a morning person, and passed away peacefully at about 8AM. We couldn't have asked for more.

All of the Bodines that I looked at have a shaft that is larger than ¼", rated at less than 1/20th HP, or DC.
 
I am hoping for a physically smaller motor. Current motor draws 0.35A, turns 3,500rpm on 115VAC, weighs ~2#
and has a ¼" shaft.

The Bodine is 11#, draws 3.3A, turns 3450rpm, is 1/6 HP (~125W) and only generates 50 oz-in (0.26 ft#).
 
Do you have a way to measure the actual speed of the lathe spindle? If not it may be worth picking up a cheap photo tach on ebay. I have one for my diesel engine, cost me less than 20 bucks and it works fine.
 
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