Jet lathe motor HELP

If you can see capacitor goo then there's a good chance that all that has happened is that you lost a capacitor, and a very slightly remoter chance that you lost a centrifugal switch or some such and that took the capacitor with it in time.

So why not just fix the motor?

I am going to rebuild it but I don't know what cap to buy. Plan is to call the local motor rebuilder and ask for a cap for 2HP XX rpm motor.

I am betting the cap is dependent on the motor speed. I have to pull the lath back from the wall to get to the motor and that is going to be a chore. I would like to have the cap in my hand when I tackle the job. It is a chinese motor.

Since you've got to do it sooner or later, do it sooner so you can get the specs off the actual motor rather than possibly-informed guesses from usenet.

If it's anything like the motor that was on my Jet 10x24, it's a piece of s*it and you shouldn't waste profanities and knuckle skin on it. Mine had a problem with the centrifugal start switch.

Or the more likely outcome is that there will be no markings on the capacitor (1980s chinese) and since it is dead I can't measure it.

What motor was on your 10 X 24?

I know chinese motors are often junk but this one has been in survice for almost 30 years. A good part of that in production so it gets some slack.

What motor was on your 10 X 24?

I know chinese motors are often junk but this one has been in survice for almost 30 years. A good part of that in production so it gets some slack.

Is it 3phase or single phase?

If you actually see capacitor goo..simply replace the capacitor. Ebay or local shops generally have the proper one.

Gunner

Single phase. I don't think three phase motors need a capacitor to start.

This post has gotten out of hand, I was hopping for a quick answer so I could buy one on the way home from work and be all set to fix it this weekend. I see that isn't going to happen. I want to get it going I feel vunrable without my lathe.

I haven't seen a lot of three phase motors with capacitors on them...

This same question gets asked and generally answered on a regular basis, and the archives can be searched thru a Goog Group search.

The Start capacitor in a capacitor start split-phase motor needs to be rated for AC, and the value of the cap should be in the range of 500uF per HP, or likely 500-750uF for a 2 HP size motor. Additionally, the appropriate cap will be rated for 120VAC or higher volts AC.

What you saw leaking may or may not be the capacitor electrolyte, but since you haven't disassembled the motor, it's mostly speculation. There could be a sheet of insulating material glued to the inside of the cap cover. Only Eyes On will determine what it is.

As you won't know anything about the condition of the motor if you only replace the Start cap, you should be prepared to disassemble the motor, especially after 30 years of use.

You should examine the mechanical parts of the centrifugal switch mechanism for wear or any other problems, and repair the parts if necessary. The centrifugal switch contacts should be closely examined, and smoothed by burnishing them, which is a better practice than filing or sanding them, which leaves sharp ridges in their surfaces which tend to melt.

Bearings are cheap if the motor is ball bearing equipped (most likely).

An internal cleaning can remove some dirt from even a TEFC totally enclosed fan closed motor. There may be loose paint, rust or other debris inside the case, and significantly more dirt if the case is vented.

An ohm meter doesn't give any useful information about the condition of a motor capacitor, unless the cap is shorted.

To confirm that an open Start cap is preventing the motor from starting, the capacitor can be bypassed, with a safe, properly insulated connection (for the dimmer ones that may read this, that means: Not a screwdriver or other hazardous method), with the load removed from the motor. Remove a drive belt or gear to separate the motor shaft from the machine.

A bypassed cap will allow the motor to start without a load, if the cap is open internally.

A capacitor start split-phase motor will start and run normally with the Start cap bypassed, and without the usual load applied to the motor.

The purpose of the Start cap in these motors is to increase the starting torque rating of the motor to meet the application. With the load removed, an good motor in otherwise undamaged condition will start and run normally.

Other internal problems mentioned may prevent the motor from starting, which is why one should be prepared to remove and disassemble the motor for inspection when any problems arise.

And that's what separates you from the self-proclaimed professional machine repair tech.. he does it for a living.

Indeed. I was way tired when I read your original post..and it didnt click. I came in from Los Angeles at 3:30 am..and was a walking doofus most of the day.

If the motor has done you good service..simply change out the bad cap with something similar. Some hardware stores stock em.

Gunner

Indeed. Mea Culpa. See previous post..no excuse..just an explaination.

Gunner

Great post. The 500 mircoF per HP is what I wanted to know. Thanks.

I recently had the same failure on a grizzly 1236. the caps were marked but I couldn't get the same size cap at Grainger. I needed the lathe up quick so I wired new caps (replace both while you're at it) in and made a new cover.

These are pretty standard values and ratings and the HVAC industry uses them all.

Simon Shabtai Evan

Update.

I pulled the lathe from the wall and looked at the capacitor. It was bulging and leaking diametric all over everything. The failed capacitor is factory supplied 110 VAC 600 microfarad beast. See Granger for a selection of motor run caps. Note the motor runs on

I really needed the lathe for a job so I took a chance and replaced the capacitor without checking the centrifugal cut out switch contacts. I tested the motor and it appeared to work so I put everything back together and started the job. Fifteen minutes into it BOOM and the starter windings are shorted to ground. It was kind of exiting because hitting the kill switch had no effect. Thank God for circuited breakers. This time I pulled the motor and look at the contacts and they are toast. I am now in the market for a new motor and spent $700 having another shop make the part.

Are the windings truly shorted, or did the cap fail short?

Bummer, if the motor really is toast.

Remember when you got motors rewound?

e quoted text -

Dead short to case. 0.2 ohms.

I talked to the local motor rebuilder and at $75 hour he said it just isn't worth it. New one cost $250 to $300.

Interesting thing. 22 mm metric shaft come out to 0.870. Now if I had a lathe that worked I could bore out the pulley 5 mill and use a n 7/8 shaft US motor.