Bent mandrel or bad bearings

[cowchaser]

Yesterday my jet mini vs has decided to come up with a vibration. When turning I am getting a decent vibration on the barrel closest to the headstock and not much on the tailstock side. I have checked the mandrel and I just can't tell. I can also on real slow speeds (500 or so) hear a small tick in the headstock. The lathe is about 9 months old or so. I have no clue on this, can anyone suggest anything here? I did also turn a pen between centers and didn't notice any vibration.

Then mandrel is one of the adjustable ones from csusa.

 

[stevers]

Not familiar with the adj ones. Easy enough to set you tool rest up close to the mandrel and spin it by hand and look for a wobble. Do you have a dial indicator. Thats how most check that sort of thing. They can be had at most mail order houses for $20.00 or less and usually come with mag bases.
Also, check your MT to be sure it's clean. Just because you did a BCB turn doesn't mean it not a little dirty inside the MT. BCB can make a small wobble almost go away.
Just a couple things to try. Good luck.

 

[RonInSpringTX]

Hey neighbor, I'm in Spring,TX (just N or Houston). We often pass right near you on our way to Kearney, Nebraska. (most of wife's family live there.)
How long you had the mandrel?? what project did you do before this one? Any chance the tailstock or the knurl nut was too tight?? I assume it's a #2 morse taper, so I doubt if it's not seated good & square to the headstock. If the mandrel unscrews from the taper, try switching them (if you have another)

good luck
Ronnie

 

[Randy_]

Could be a million things. I will mention a few things to check and other will add to the list.

Check that the pulley on the motor shaft and the spindle are tight. Sometimes the set screws loosen up. Same thing for the hand wheel. Also check your belt. If there is a chunk missing or it is not aligned properly, that could cause a vibration.

Take the mandrel out of the holder and roll it on a smooth surface like the glass surface of a coffee table. It should be easy to detect a bent mandrel.

Grab the spindle and shake it back and forth and in and out. If you detect any movement at all, either the bearings are going out or the handwheel is not tight.

Also agree with the previous suggestion to be sure the MT socket is absolutely clean.

Generally inspect the inside of the headstock to make sure something is not rubbing. If you have the new model with the indexing pin, make sure it is not rubbing against the pulley.

Loosen the motor mount so the belt is not firm to the pulleys and then spin the spindle by hand and see if you hear any noise of feel any roughness or rubbing.

 

[cowchaser]

Okay, I have done all of the above except put the mandrel on a caliper since I don't have one right now. Placing the tool rest very close and turning it appears to show the smallest of space developing during rotation closest to the headstock. With the tailstock pulled away it shows signicant gap appearing on rotation on the tailstock end. Everything with the lathe appears to be normal. So I will try a new mandrel. Just order a couple from jcollazo and for as cheap as he has them even if it's not the mandrel it don't hurt to have a few around. So when they come in I will try a new one and go from there. I appreciate the suggestions so far. I am not the most mechanically inclined person around.

 

[stevers]

This is a great set of articles and tips on mandrel maintenance and repair. May be some tips in here to help while you wait for your new parts. And not to burst your bubble, but I have tuned up the last couple of mandrels I bought before I even used them. All the handling can do things.
Good luck.
http://www.woodturner-russ.com/Pen12b.html
Just look down the page and there are several neat tips.

 

[markgum]

Originally posted by stevers

Not familiar with the adj ones. Easy enough to set you tool rest up close to the mandrel and spin it by hand and look for a wobble. Do you have a dial indicator. Thats how most check that sort of thing. They can be had at most mail order houses for $20.00 or less and usually come with mag bases.
Also, check your MT to be sure it's clean. Just because you did a BCB turn doesn't mean it not a little dirty inside the MT. BCB can make a small wobble almost go away.
Just a couple things to try. Good luck.

what is a BCB??
thanks.

 

[stevers]

Between center bushings. Turning without mandrels.