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Atlas/Craftsman 12x36" lathe...questions
- Thread starter Jason280
- Start date
First thing to do is put in a new start capacitor. These things have a limited life span and a new one will revive the a good motor.
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- Dec 3, 2017
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I'm sure Wa5cab knows for certain, but I don't even think you need a 3/4 hp motor. There are expensive and difficult to replace items in between that motor and the piece of metal you're turning. Any opportunity to save those bits will help. A half of one horse power is really quite a bit of power. I don't know if you've ever had horses, but yeah....They're pretty strong critters. Anyways, you can always run the belt a little loose or something. My little Ammco shaper has a 1/3 hp motor on it, and that motor does not stall. The belt will slip long before the motor shaft even begins to pretend it might slow down.
A start capacitor can be had for fairly cheap by comparison to the motor. It's not a bad idea to try it. But I get your point on making it turn the right direction first. Your machine there should have at one time, had the reversing switch I'm talking about. But maybe that was an option the PO chose not to avail himself of.
Any luck with the lead screw?
A start capacitor can be had for fairly cheap by comparison to the motor. It's not a bad idea to try it. But I get your point on making it turn the right direction first. Your machine there should have at one time, had the reversing switch I'm talking about. But maybe that was an option the PO chose not to avail himself of.
Any luck with the lead screw?
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- Apr 30, 2015
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I'm familiar with that style of motor and it should be fairly easy to reverse. Likely needs a new starting cap or there's a problem with the starting switch inside.
You probably can find a good used US motor locally on Craigslist
Mark
You probably can find a good used US motor locally on Craigslist
Mark
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- Dec 25, 2011
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- 10,552
First off, the motor claims to be a 1 HP unit, but that is the approximate input power, not what the motor will output. It would output 1 HP only if it were 100 % efficient, which no motor is. It's the worst case of over rating that I recall seeing. The motor is actually a 1/2 HP unit if you rated it at approximate output power at typical efficiency.
Secondly, the standard voltage in the USA has been 120 VAC per side for well over half a Century, not 110 VAC. So someone over there is still living in the first half of the last Century. I wrote recently in another thread that you could roughly date a used capacitor start motor by the nameplate voltage. But not so with this one as whoever made the nameplate claimed it was made in 2002.
At any rate, if you ignore the misleading nameplate data, the motor is the right size for this machine. The motor appears to be in good condition at least externally. So if you have no need for a reversible motor, and can reconnect it internally to turn in the correct direction, it is probably worth buying a new START capacitor for it. To reconnect it, you will need to remove the motor end-bell and bearing support probably from the end that the wires come out of and locate where the START circuit is connected in parallel with the RUN circuit or windings. If you disconnect the start winding, switch and capacitor from both sides of the RUN windings and reconnect each end to the opposite end of the RUN windings, the motor will start and run in the opposite direction. However, if you decide to replace the START capacitor and keep the motor, I would suggest taking the as-is motor to a motor rewind shop and ask them to do it. They will already know what to look for.
Secondly, the standard voltage in the USA has been 120 VAC per side for well over half a Century, not 110 VAC. So someone over there is still living in the first half of the last Century. I wrote recently in another thread that you could roughly date a used capacitor start motor by the nameplate voltage. But not so with this one as whoever made the nameplate claimed it was made in 2002.
At any rate, if you ignore the misleading nameplate data, the motor is the right size for this machine. The motor appears to be in good condition at least externally. So if you have no need for a reversible motor, and can reconnect it internally to turn in the correct direction, it is probably worth buying a new START capacitor for it. To reconnect it, you will need to remove the motor end-bell and bearing support probably from the end that the wires come out of and locate where the START circuit is connected in parallel with the RUN circuit or windings. If you disconnect the start winding, switch and capacitor from both sides of the RUN windings and reconnect each end to the opposite end of the RUN windings, the motor will start and run in the opposite direction. However, if you decide to replace the START capacitor and keep the motor, I would suggest taking the as-is motor to a motor rewind shop and ask them to do it. They will already know what to look for.
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- Dec 25, 2011
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- 10,552
On the question of removing the lead screw in order to remove the QCGB, there are no set screws to loosen. The collar that is visible where the lead screw goes into the gearbox is there to adjust the end float of the L6-1040 gearbox output shaft. This shaft is hollow and has an internal key that the 5/8" diameter end of the lead screw engages. If you want to see what the parts look like, the installation and parts manual for the 101.20140 QCGB is in Downloads.
When you said that the lead screw only moved 1/4" to 1/2", did the collar movement account for part of that? Probable you need to rotate the spindle with tumbler engaged so as to bring the long lead screw keyway to TDC and then soak the end of the lead screw where it goes into the shaft. Also soak the set screw in the collar in case you later decide to disassemble the gear box. My guess is that the lead screw is just stuck in the output shaft.
In the event that soaking with penetrating oil doesn't quite do the trick, the other or final option is to remove the lead screw right support bearing which will expose the jam nut threads on the right end. These threads should be 1/2"-20. Borrow or rent a slide hammer puller. If it doesn't come with a set of adapters, you will need to make a double female adapter. One end would be threaded 1/2"-20. The other end would be threaded to fit the threads on the end of the puller bar.
Your only other option in the case of a stuck lead screw would be to remove the tailstock and carriage from the bed. Then remove the gear box with lead screw in place. With the gear box inverted, you should be able to remove the circlip from the inner end of the output shaft. That will allow you to remove the output shaft and lead screw. With a support bar with 3/4"+ hole drilled through it, you will be able to press the lead screw out of the hollow shaft.
When you said that the lead screw only moved 1/4" to 1/2", did the collar movement account for part of that? Probable you need to rotate the spindle with tumbler engaged so as to bring the long lead screw keyway to TDC and then soak the end of the lead screw where it goes into the shaft. Also soak the set screw in the collar in case you later decide to disassemble the gear box. My guess is that the lead screw is just stuck in the output shaft.
In the event that soaking with penetrating oil doesn't quite do the trick, the other or final option is to remove the lead screw right support bearing which will expose the jam nut threads on the right end. These threads should be 1/2"-20. Borrow or rent a slide hammer puller. If it doesn't come with a set of adapters, you will need to make a double female adapter. One end would be threaded 1/2"-20. The other end would be threaded to fit the threads on the end of the puller bar.
Your only other option in the case of a stuck lead screw would be to remove the tailstock and carriage from the bed. Then remove the gear box with lead screw in place. With the gear box inverted, you should be able to remove the circlip from the inner end of the output shaft. That will allow you to remove the output shaft and lead screw. With a support bar with 3/4"+ hole drilled through it, you will be able to press the lead screw out of the hollow shaft.
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- Dec 25, 2011
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One other thing that I will mention about motors if you are going to buy a new one is this. Places like WW Grainger have some of their motors in groups of three. The first one is without thermal overload protection. The second one has thermal overload that does not reset itself when the motor cools off. Manual reset only. The third one has automatic reset. Do not buy the third one for any machine tool. If something happens while running, it will try to re-start about the time you have your nose down in there trying to figure out what went wrong!