Excessive lathe vibration

[Dave B]

Hi all,
I am looking for some advice please regarding the vibration when running my lathe unloaded.
I have an Axminster craft AC370WL which has a viromatic speed control.
This happens through all the speeds but is stronger in some compared to others. I think it is possibly coming from drive belt chatter? But I might be wrong....
It can be felt when my hand is placed on top of the headstock guard.

I have checked the bearings for ware and there is no play there at all. When the drive belt has been disconnected, the headstock shaft spins freely and the motor a free as well.
I would be really greatful for any support in resolving this issue.
Many thanks.
Dave.

 

[deema]

Disconnect the belt and see if the vibration is still present with just the motor running. (I don’t know the lathe and Im assuming it’s belt drive). If it is, it’s probably the pulley that’s not been dynamically balanced.

 

[Inspector]

It has the cone pulley dive where one closes increasing the effective pulley diameter and at the same time the other opens decreasing decreasing the effective pulley diameter. Those types of variable drives can be a pain if not properly lubricated or are wearing out. The belt could be worn, the cone splines worn/loose, bearings/bushings in the drive could be starting to wear. Someone with a better understanding would know if it can be run with the belt off to see if it is the motor. The manual is available online if the paper one is gone.

Pete

 

[Dave B]

Hi guys thanks for your reply.
I removed the drive belt and run just the motor. The vibration wasn't there.
After refitting the belt I run it again I did notice that there was approximately 8 to 10mm of deflection on the belt at the longest stretch. When stopped the belt tension is nice and tight so if like Pete said, maybe a worn belt or chattering cone splines is the culprit.

 

[Sandyn]

I have vibration with my bandsaw, which is caused by a slightly uneven floor. Are all the feet in good contact with the ground? if not, it can cause resonance of the machine and amplify vibrations. If you have your hand in contact with the foot and ground, you should be able to feel if there is any movement. I use a very thin wedge and push it under the problem foot.

 

[Dave B]

Thats a good point about the legs contacting the ground now you've come to mention it. I have recently got 4 anchor bolts to fix the legs down tight to the concrete floor in my shed. I have been mounting some chunky bowl blanks for green turning and it has been bouncing around a bit for the first 5 to10 minutes or so.
I will crack on and get it secured down nice and tight and I have ordered a new drive belt incase the existing belt is worn, doesn't look to bad but could be wrong.
Thanks again all of you.

 

[WaggaSteve]

It has the cone pulley dive where one closes increasing the effective pulley diameter and at the same time the other opens decreasing decreasing the effective pulley diameter. Those types of variable drives can be a pain if not properly lubricated or are wearing out. The belt could be worn, the cone splines worn/loose, bearings/bushings in the drive could be starting to wear. Someone with a better understanding would know if it can be run with the belt off to see if it is the motor. The manual is available online if the paper one is gone.

Pete

if I'm right in thinking these are known as Reeves drives , what maintenance and what frequency is required please

 

[Inspector]

The manual for the lathe should have it.

I did a search and found information for some. You’d need to go through it and glean relevant information from it.
http://12.139.238.171/Library/Manuals/REEVES VARI SPEED DRIVE.pdf
Pete

 

[okeydokey]

When changing the belt UNDER NO CIRCUMSTANCES be tempted to lever the reeve drive cones/pulleys they are so brittle and snap easier than egg shells.

 

[Dave B]

The manual for the lathe should have it.

I did a search and found information for some. You’d need to go through it and glean relevant information from it.
http://12.139.238.171/Library/Manuals/REEVES VARI SPEED DRIVE.pdf
Pete

Thanks for sending this manual. I did read from it that it is possible if the lathe has been standing for a 30 days, the spring tension on the pulleys can cause the belt to compress. This could possibly be causing my belt to flex up and down 10mm as it runs.
I have a new belt ready so just for an experiment, will replace the old belt before going in deeper to see if it makes any difference.

 

[Dave B]

When changing the belt UNDER NO CIRCUMSTANCES be tempted to lever the reeve drive cones/pulleys they are so brittle and snap easier than egg shells.

Yes those drive cones do have a bit of a ring to them

 

[clogs]

about the belt, over time they harden and occ at where they touch the pulley's they can be miss shaped.....after a long time of no use....
belts are very cheap, just buy a new one before tearing the lathe apart.....

 

[WaggaSteve]

The manual for the lathe should have it.

I did a search and found information for some. You’d need to go through it and glean relevant information from it.
http://12.139.238.171/Library/Manuals/REEVES VARI SPEED DRIVE.pdf
Pete

Thank you. The lathe is in a mens shed , donated by some kind person but understandably no manuals

 

[Fergie 307]

about the belt, over time they harden and occ at where they touch the pulley's they can be miss shaped.....after a long time of no use....
belts are very cheap, just buy a new one before tearing the lathe apart.....

I would go along with that. If it's been sitting unused for ages the belts may have become moulded to the shape of the pulleys, for the relatively small cost involved I would put new ones on and see if that cures it.