The Dreaded Vibration Question...

Signed-In Members Don't See This Ad

LK&T

Member
Joined
Dec 1, 2020
Messages
139
Location
Sedro Woolley, WA
Y'all know where this is going, so I'll just get to the nitty gritty. Lathe is a Jet 1015, non VS. Less than a couple years old. The past couple days I've picked up a loud, high pitched vibration when cutting towards the tailstock. There is no vibration or noise when cutting near the headstock, but as I move towards the tailstock it starts. Does it with roughing gouge, skew and scraper. It is dead repeatable. I've checked the live center, and I can't feel any roughness or play in the bearings. I cleaned the inside of the tailstock taper, cleaned the live center taper and checked them both for defect and found none. I took off the tailstock, cleaned the bottom, cleaned the bed, cleaned the banjo and gave everything a good look. Again, I found nothing suspect. Put everything back together and put in a live center that I know to be good. Still high pitched vibration. Sigh....... I can't get over that it's the live center. Up till now I've bought cheap live centers and I think that's the issue. Today I drove up to Grizzly and bought a Teknatool live center set. Didn't get to play with it today because I'm sick. No, not THAT. Just an everyday cold that's kicking my butt pretty hard. Felt like junk when I got home, so I didn't go to the shop. Anyway, I'll try it tomorrow and see what happens.

So, in case it's not the live center (which is a real possibility) what do you folks think? What's good to check next?
 
Signed-In Members Don't See This Ad

Kenny Durrant

Member
Joined
Sep 11, 2012
Messages
2,480
Location
Sachse Tx. 75048
Are you using a mandrel with a tapered live center. It's been a while because I switched to the mandrel saver so I don't know if there's been any updated or how my memory is with the numbers. When I was using a regular mandrel I had the same trouble. The culprit was that the live centers taper didn't match the one in the end of the mandrel. I was first told to barely file off the sharp point of the live center and that helped for a while. The vibration was coming from the fit between the mandrel and live center. The degree of the angles didn't match so it was only a period of time before it would wear and start giving me trouble.
 

LK&T

Member
Joined
Dec 1, 2020
Messages
139
Location
Sedro Woolley, WA
Are you using a mandrel with a tapered live center. It's been a while because I switched to the mandrel saver so I don't know if there's been any updated or how my memory is with the numbers. When I was using a regular mandrel I had the same trouble. The culprit was that the live centers taper didn't match the one in the end of the mandrel. I was first told to barely file off the sharp point of the live center and that helped for a while. The vibration was coming from the fit between the mandrel and live center. The degree of the angles didn't match so it was only a period of time before it would wear and start giving me trouble.
That's an excellent point, and I should have said how I was turning. I am not using a mandrel; I'm turning between centers with no bushings. That should be the least amount of error you can introduce with alignment.
 

Charlie_W

Member
Joined
Nov 16, 2011
Messages
5,918
Location
Sterling, VA USA
Are you using your tail stock quill lock? I have found that on a number of lathes, there is play between the quill and the tail stock bore. This is aggravating when drilling or threading and could introduce some movement/vibration while turning near the tail stock.
 

leehljp

Member Liaison
Joined
Feb 6, 2005
Messages
9,314
Location
Tunica, Mississippi,
The basic list:
Mandrel and wrong live center - you are not using that.
Live Center Bearings: You have a new live center; we will wait for the results
Blank properly squared?
Tail Stock and Head stock line up?
Tail Stock locked down tight?
MT clean? Loose?
Sharp Tools? Sharp tools are subjective. But an ever so slightly dull tool requires a bit more force which, in combination with any of the 4 above situations, (and the situation as Charlie mentioned above) can set up vibration.
 

TonyL

Member
Joined
Mar 9, 2014
Messages
8,904
Location
Georgia
Are you using your tail stock quill lock? I have found that on a number of lathes, there is play between the quill and the tail stock bore. This is aggravating when drilling or threading and could introduce some movement/vibration while turning near the tail stock.
I was going to say the same thing. on my older 1221, sometimes it get loose.
 

RobS

Member
Joined
Jun 20, 2016
Messages
1,037
Location
Carlsbad, CA
there is one item missed on the list but eluded to above, and has come up recently for me, when researching if my lathe bearings are starting to go. It is possible, that your headstock bearings are starting to show wear, and that has changed the behavior of your lathe. I would also check with a different piece of material and confirm it happens with different blanks. If it does, then the headstock may be the problem, if you have vetted all other options above.
 

LK&T

Member
Joined
Dec 1, 2020
Messages
139
Location
Sedro Woolley, WA
Well folks the results are in, and it's live center by a landslide. First thing I did today was break down the tailstock assembly to parade rest and clean/grease everything, all the while looking for problems. No problems found, so back together and onto the bed. Then I broke out the dial indicator and measured everything, both headstock and tailstock. Everything basically measured same as new. Measuring the 60 degree, piece of junk live center I was using was telling. I couldn't feel any play in the bearing with my fingers, but I could make the indicator swing .009 with light finger pressure, and more if I tried harder. I then measured the new Teknatool live center. The body measured just under a thou for runout, which is a good number. Also, couldn't get more that .0005 out of it when I wiggled it. I put the 60 degree insert into the body and measured it...... over .010. (insert angry face here) Pulled the live center apart, messed with it, and determined there was a little burr somewhere because I could make the insert click and rock a little bit with my fingers. I considered applying a little sandpaper to the insert and the taper in the body, but deciding that flushing my warranty down the toilet so soon wasn't worth it. Put the live center back on the lathe and chucked up a blank. I heard a click as I tightened the tailstock, so I figured I'd just run it a bit and see if that helps. So I do that, but don't make any cuts. Took off the blank and measured again at the 60 degree insert and get .0035. Now we're talking! I checked with my fingers and can't make it wiggle anymore, so I believe a little brute force and ignorance solved that one. As an aside boys and girls, remember that brute force and ignorance works every time it doesn't..... your mileage may vary. After all this I put the old live center in the lathe, chucked up a blank and took a few cuts. The vibration was back. Then in goes the Teknatool live center, take a few cuts and vibration is gone. Not even a hint. (insert happy face here)

Lessons learned:
- Cheap tools are just that. I mean, I knew that but I was hoping a $15.00 live center would live on a small lathe. Not.
- I now have some baseline measurements from the dial indicator to troubleshoot live center bearings.
- It's good to take apart the lathe and clean it every now and then, even if it doesn't need it.

Sorry this was so long winded, but I wanted to get the whole story so it might help someone else. And thanks to every one who responded. As usual it's all good advice!
 
Top Bottom