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Lathe singing

M

Mike Novak

Joined
May 30, 2022
Messages
360
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343
Location
Belchertown, MA
I’m starting to have trouble with vibration on my Laguna 12/16. I’m hoping maybe someone here might have some ideas.

This is not the lathe shaking from an out of balance blank, and it’s not on any particular type of turning. It’s high pitched, It seems almost like when rubbing a finger on the rim of a wine glass. Changing the speed of the lathe doesn’t seem to change the pitch much. It’s getting worse as time goes by.

I’m getting it on fat spindles between centers, on bowls on faceplate with tail stock in place, before hollowing, and when outboard turning. On bowls, it’s worse closer to the center than at the rim.

My sharpening skills are better than ever, as is my ability to get clean tear free cuts. I even sometimes get vibration when shear scraping fine finish cuts. I even ground off the heel of my bowl gouge. But the vibration continues to get harder to control. I fear it may not be a technique problem.

So far I have checked that the bolts holding the headstock are tight. Im ruling out a tailstock problem because I get it when not using tailstock. I can’t see anything obvious wrong with the banjo. It happens with both tool rests.

The bearings were starting to get a little noisy after a year of use, so I replaced them with a better grade, but that did not help.

Anyone have ideas what else I could look at or try?
 
Mike Novak said:
Anyone have ideas what else I could look at or try?
Click to expand...

I’d check the belt and pulleys.
Check vertical alignment on the pulleys. If it is off check the motor Mount to be sure the motor has not moved.
Align the pulleys if needed.

Make sure both the pulleys have all their set screws tight.
Check the belt for wear and be sure the belt is seated on the pulleys.
Tension the belt slightly.
 
I agree, check the belt pulleys. I also had that problem on a different lathe from making the belt too tight. If it’s not either of those my next guess would be a bearing.
 
I checked the belt alignment and tension today. I could not see anything wrong. I already replaced bearings, so ruled that out also.

Any other Things I could check?
 
How often do you turn? Replacing bearings after one year is just crazy! I have a 24 year old lathe on the factory bearings. To go through bearings that often, you are cranking the tailstock WAY TOO HARD! Did you check the bearings in the live center?
 
Did you call Tech Service? When I used to turn on a 12|16 I called about a problem and they sent a brand new lathe, with pretty much no questions asked.

Although I will admit that their service is not really the best.
 
Richard Coers said:
How often do you turn? Replacing bearings after one year is just crazy! I have a 24 year old lathe on the factory bearings. To go through bearings that often, you are cranking the tailstock WAY TOO HARD! Did you check the bearings in the live center?
Click to expand...

I think the main cause was me torquing too tight when I installed the adapter for outboard turning, plus too much tailstock pressure when I was first starting. I replaced both headstock bearings and the one in the live center.


Gabriel Hoff said:
Did you call Tech Service? When I used to turn on a 12|16 I called about a problem and they sent a brand new lathe, with pretty much no questions asked.

Although I will admit that their service is not really the best.
Click to expand...
I think this is my next step, after I try Doug’s idea about loosening and retightening the head bolts.

Dennis, Stu, it’s not electronic. Only happens when I’m cutting, and I can see the impact in the cut
 
Spindle bearing preload? The wave washer should be compressed at least 50%. Try different amounts of preload and see if that makes a difference. Did the new spindle bearings slide on the spindle w/o a lot of force?

Cracked/broken brush in the motor? Be sure the brushes are returned in the same orientation as removed. A problem in the DC Drive electronics? Check all electrical connections.
 
With a whine of that frequency, would be looking at electronic harmonics, I would check the VFD for something loose.
 
Gabriel Hoff said:
I had a lot of issues with the outboard turning adapter. It had a lot of runout and noise
Click to expand...
I had to have the first one replaced, both run out and wobble. The second one they sent does not wobble, and the threads are concentric, so the chuck runs true, but the body still has run out.
 
Two guys I think have pointed in the right direction.
A VFD can have a high pitched whine. Put your ear near the VFD while the lathe is idling. That should give you a clue if the noise is coming from the VFD.
Our club has a lathe that has that whine. I can hear it plainly even in the back of the room. Others can't hear it. Depends on whose ears are listening.
 
Bob Vaughan said:
Two guys I think have pointed in the right direction.
A VFD can have a high pitched whine. Put your ear near the VFD while the lathe is idling. That should give you a clue if the noise is coming from the VFD.
Our club has a lathe that has that whine. I can hear it plainly even in the back of the room. Others can't hear it. Depends on whose ears are listening.
Click to expand...
Or stop at an auto parts store an pick up a stethoscope. Mechanic’s version comes with a metal rod—amazing how it can help isolate odd noise. Do NOT use on spinning parts while they are spinning!! But on the VFD housing while the noise is happening might help you out.
I’ve had mine for a few decades, and it’s one of those gadgets I wouldn’t be without a few times a year.
 
I owned this machine for over a year and it is not the motor. It does not make much noise when working properly. Did you check for debris in the pulley grooves? If something is stuck between the grooves it can sometimes make noise. Like the others say, check the VFD.
 
None of the suggestions so far seem to be it. I’m waiting for a callback from Laguna tech support. I’m starting to suspect something cracked, warped, or twisted.

I did notice that the headstock moves by about 0.001” away from the tailstock when I lock the banjo in place. I can also move it 0.001” by pushing on it with one finger. I’m surprised it’s not more rigid. I’m also surprised how easy it is to see 0.001” movements, but it’s hard to measure.

The only thing I can think of that changed is my wood is getting dryer. Most was harvested last winter.
 
I will sometimes hear the wood "singing" or more often "humming" (the wood usually doesn't know the words). This happens for me when the wood is thin (like a thin-walled bowl, near the rim) and I'm probably pressing too hard with the gouge or something. Changing things (my approach, speed, etc) usually takes care of it. When the bowl just wants to vibrate anyway, I'll put a leather glove on my left hand and use some fingers to stabilize the vibration.
But it sounds like your noise is happening in lots of different scenarios, so this is probably not related.
Your best bet might be to find someone else (another experienced club member) to help in person. Another set of ears might be needed. also you could let them cut with their tools to see what happens; take your wood/tools to their lathe; etc - rule some things out to see if it's the machine, wood, tools, turner, etc)
 
Mike Novak said:
The only thing I can think of that changed is my wood is getting dryer. Most was harvested last winter.
Click to expand...

Well dang, didnt even think of that. I strongly suspect that is the culprit. Big differences occur in cutting, sounds, etc depending on how dry the wood is. Get some wet stuff to test it out.

Wall t is a big player in creating “singing”, ie a resonance created by the material, cutter, rpm, etc, and material moisture content is also a big player.
 
Doug Freeman said:
Well dang, didnt even think of that. I strongly suspect that is the culprit. Big differences occur in cutting, sounds, etc depending on how dry the wood is.
Click to expand...
I find that is very common with extremely dry wood. I don't work with large pieces anymore, but is did happen on maple, oak, and boxelder pretty commonly. You can get that loud chatter and flexing, which make a high pitched "ringing" sound
Doug Freeman said:
Get some wet stuff to test it out.
Click to expand...
Good idea.
 
Since it affects the surface finish I think you can rule out any electronics. Have you checked runout on the drive spindle? A steel dowel mounted in a precision chuck would accentuate the issue for easier measurement.
 
I rearranged my workshop, moving the lathe to a different spot, and now I’m not having near the problem I was. I wonder if the workbench was not level, causing the lathe frame to twist? It’s bolted to the bench, and the bench has 150lb of sand on a shelf.

The lathe itself, laguna 12/16, is much less rigid than I thought. I bought a dial indicator to check for movement. The headstock moves away from the tailstock by 0.001 just from locking the banjo. I can move it thru almost 0.002 just by pushing it with 1 finger. It moves 1/32 with tailstock just snug. I did not check runout, but the outboard adapter has visible runout.

I’m starting to wonder if I’m just expecting too much from a small lathe. Or if there is a crack in the frame somewhere.
 
I suspect the issue is quite different. After a few weeks of turning, I pick up a medium to high pitch hum while rubbing the bevel.
Dust collects under my headstock, banjo and tailstock. Granted, my headstock rotates and slides, so that is different than yours.
What is the same, is the fine dust. After I clean all the mating surfaces to the bed rails, and wax the rails for rust protection... The noise goes away.

I wonder if dust has compressed in the headstock mating surface to the lathe bed, between the tailstock and the lathe bed and under the banjo. If you haven't cleaned, dusted and waxed the surfaces in a while I would do that regardless of the noise.
 
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