Lathe making a grinding noise

[Eric Gourieux]

A friend recently purchased a full size variable speed Craftsman lathe (model number 351.21717) that was supposed to have never been used. It had 2 previous owners. One died and the other decided to purchase a smaller lathe. Anyway, when the lathe runs with nothing on the spindle, it is relatively quiet. When he runs the lathe with any "load" on the spindle - even an empty chuck or faceplate, the motor makes a grinding or crunching noise. No squealing. It sounds the same regardless of the speed. The spindle runs true.

Has anybody experienced a similar problem? I know it is hard to describe a sound, which may make this a difficult question to answer. It's odd to me that the sound doesn't occur with nothing on the spindle.

Any help or suggestions would be appreciated.

[Josh Bowman]

Start looking toward a bearing. Either the head stock or motor. Bad bearings may not show themselves until loaded. Good luck

[neil mackay]

Start looking toward a bearing. Either the head stock or motor. Bad bearings may not show themselves until loaded. Good luck

I agree, bearings

[Thom Sturgill]

I looked up that model - similar to the Nova the motor is in line with the spindle (spindle and rotor one piece?) and it is electrically variable. Probably still bearings, but I would expect the sound to change with speed.

[Duane Meadows]

There are 2 version of that variable speed lathe. If it is the electronic speed control version(and it sounds like it is), the gearbox has a habit of throwing the grease away from the gears. I have heard of guys filling the gearbox with a heavy gear oil instead of the grease. Be sure the gearbox is well sealed so it doesn't leak.

That said, mine has been noisy for years and really hasn't caused a problem. However, i don't use it that much either. Sears has a replacement head available(or used to, anyway) that has a different VS system altogether. However the price is close to the price of the lathe. I have changed several of these under warranty or service contract for customers.

[Duane Meadows]

I looked up that model - similar to the Nova the motor is in line with the spindle (spindle and rotor one piece?) and it is electrically variable. Probably still bearings, but I would expect the sound to change with speed.

Nah, it has a 4 to 1 reduction gear box!

[Roger Chandler]

Eric,

What you have there.... a spindle that is turned.......mechanically, not by belts but by gears. I had one of these and it did well until I had a chuck lock on the spindle and in trying to get it off, I broke the gear shaft..........

The noise it makes is from the "transfer case" if you want to call it that........where the gear on the motor shaft mates up with the gear on the lathe spindle.....this area is packed with grease, and should be fine, unless the grease has gotten old and somewhat dried out. If you are handy with mechanical things, you can take the headstock apart a pay attention to the way everything mates up and put new grease into the area and it should quieten down for you, but you will always have some noise, which is normal.

The motor is a 10,000 rpm d/c motor and the gears reduce the speed and a controller allows it to be variable speed via a potentiometer.

I don't think you will be able to get many parts .......that lathe is totally out of production and when I broke my gear shaft, I could not find one on planet earth. I even went to machine shops and only one was even willing to make one, as it requires a hobbing machine to mill it, and they wanted some $900 to make me a couple of them.......all the setup time, etc......the lathe was only about $600 when I purchased it new.

Perhaps a used lathe could be found for spare parts........I ended up putting mine in the scrap metal yard about 4 years ago.

Feel free to send me a pm if I can be of further assistance!

[Thom Sturgill]

Interesting. I had not seen one of these before, just going from the picture. I would assume this means the spindle is solid so no vacuum chuck without some special adapter and no drilling through the head. gear driven would tend to be noisy, but should provide good torque, no?

[Duane Meadows]

Interesting. I had not seen one of these before, just going from the picture. I would assume this means the spindle is solid so no vacuum chuck without some special adapter and no drilling through the head. gear driven would tend to be noisy, but should provide good torque, no?

Yep, you are correct about the vacuum chuck and drilling issue, Thom. One of a couple of reasons that knowing what I know now, I probably would buy a different lathe. But it really has served me well for quite a few years. Just depends what you are turning.

[Eric Gourieux]

Thanks for all of your suggestions. I'll pass this on to him. He's a bit bummed!