Spindle/Motor/Bearings Running Hot

[candy1land]

My lathe is about 7 years old but it has sat for the past 5 years doing nothing. I just started turning again and I bought a mandrel saver. I've noticed after only turning 3 pens that my spindle handle gets really hot while I'm turning and so does my motor now. I don't recall this being the case before. I have a delta midi lathe. There was a service announcement about the spindle being too tight from the factory so I did the fix and loosened it about 1/8 of a turn and things still run hot whether I'm turning something or not. Any suggestions? Does this mean I need to replace bearings? If I do how would I know? I don't want to burn out the motor that's for sure. The belt looks fine. Things are lined up.

Thanks for the help.

 

[gtriever]

Make sure you're not over-tightening the mandrel saver against the bushings. I've noticed that when I do, everything will heat up. There's a "sweet spot" between too loose and too tight.

 

[Charlie_W]

If you remove the belt and spin the spindle by hand, is there any resistance or bumpy feel? If so, go ahead and replace the spindle bearings. If the bearings are causing extra drag, the motor has to work harder.....and will most likely have a shorter lifespan.

You can also use a mechanic's stethoscope to listen to the bearings both while you turn the spindle by hand and also while running. Sometimes a long screwdriver or pipe can be used in place of the stethoscope.
Bearings are less expensive than motors.
Good Luck!

 

[randyrls]

There was a service announcement about the spindle being too tight from the factory so I did the fix and loosened it about 1/8 of a turn and things still run hot whether I'm turning something or not. Any suggestions?

The other suggestions are good ones.

You may need to loosen the bearings more. On metal lathes this is call "preload" and is usually set by temperature. Run the lathe at its highest rated speed under no load, and check the temp after 15 minutes. If the spindle nose is hot, back the preload off more. You should be able to touch and hold the spindle nose. It will be warm, but not hot to the touch. The spindle nose should not have any free play in it.

Another possibility is the grease in the bearings has thickened and the bearings are heating from the friction. This may be caused by the hot temp. On some lathes you can add some solvent to free the bearings up or clean and replace the grease or oil used in the bearings.

Lastly, check the pulleys and make sure the set screws that hold the pulleys are not loose.

 

[Ed McDonnell]

Just in case you don't have a mechanics stethoscope laying around, you can use a large screwdriver with a plastic handle. Put the screwdriver blade against the housing and put the plastic handle to your ear. Turn the spindle by hand and listen for clicking / grinding / other funny noises. Don't do this while the lathe is running to avoid accidentally having the screwdriver handle pushed through your head

Ed

 

[frank123]

How fast does it slow down when you turn it off, both with and without something mounted in it?

Rapid slowdown with nothing in it would indicate either lack of bearing lubrication (which is quite possible in either the motor or the spindle head after sitting that long) or faulty bearings. Rapid slowdown with something mounted would indicate a mounting problem of some kind unless you have really lots of end play in the headstock bearings.

If it wasn't doing it before standing, and standing was the only thing different, I'd think failing lubrication would be most likely. That may be correctable to test it.

 

[candy1land]

Ok, I don't know how to upload a video but I tried the "slow down" test and it seems it does slow down fairly quickly. If I find a way to post a video I will post them for you to see.


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[candy1land]

I figure it out. This is without the tool.
https://youtu.be/5ex580wQwvw


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[candy1land]

Slow down with the tool
https://youtu.be/hgCcNheDynA


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[candy1land]

If you remove the belt and spin the spindle by hand, is there any resistance or bumpy feel? If so, go ahead and replace the spindle bearings. If the bearings are causing extra drag, the motor has to work harder.....and will most likely have a shorter lifespan.



You can also use a mechanic's stethoscope to listen to the bearings both while you turn the spindle by hand and also while running. Sometimes a long screwdriver or pipe can be used in place of the stethoscope.

Bearings are less expensive than motors.

Good Luck!

When I remove the belt and just hand turn the spindle it seems to spin freely and fine. No bumps. No stethoscope but I tried the screwdriver thing and heard nothing either.


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[candy1land]

How would I use a solvent to clean these? If the lubricant has gotten too thick that may be some of the problem?

I checked the set screws on the spindle wheel and it's tight - from factory.

The set screws on the spindle handle is also tight.


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[PatrickR]

By hot do you mean, you can or can't hold your hand on it? The bearing is surely a sealed, permanently lubricated type. If it is so hot you cant keep your hand on it for any length of time it will need to be replaced.

 

[candy1land]

By hot do you mean, you can or can't hold your hand on it? The bearing is surely a sealed, permanently lubricated type. If it is so hot you cant keep your hand on it for any length of time it will need to be replaced.

I wouldn't say it gets so hot I can't touch it but the motor and the spindle handle and the area around the bearings gets hot enough that I wouldn't want to leave my hand on it for more than a few seconds.

I ordered bearings today just in case. I have a feeling that is really the only thing I can try besides loosening the spindle handle off the bearings on that side which I already did.


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[PatrickR]

Sounds like the best corse of action. The bearings likely dried out from sitting.

 

[frank123]

Sometimes you can use a hypodermic needle (the sharp pointed ones for injections, not the blunt ones used in ink refill kits) and inject some light oil into the bearing and it will mix with whatever dried out lube is in there and you'll be good to go again.

Depends as much as whether you can get to the seals and if they're metal shielded or not as anything else to be able to do it.

 

[KenV]

Heat varies from lathe to lathe. Temps of 120-140 degrees F are not out of the ordinary.

Unless there is drag or vibration, keep running until you get the indications of bearing problems. Your description suggests you are in high normal. My big lathe routinely gets to about 130 degrees measured with a bbq thermometer.

Having a spare set of bearings on hand is prudent. Keeping track of where they are at becomes the challenge.

 

[candy1land]

Thanks KenV I ordered the bearings. I turn until it's get too hot and then I give it a rest. Sucks because it's always when I'm in a rhythm. I will see if I can determine the temp next time - I'm curious.


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