Chasing down lathe vibrations

[RichardG]

I have an old blue record power CL3-36 lathe mounted on the metal record stand. I've set it up at 24inch width and hung the longer bars over the end by the headstock/motor. I haven't yet bolted the lathe to the concrete floor as I'm not 100% sure I'm going to keep it in its current position. It has been levelled.

This is my first lathe and I have never turned wood before so I'm slowly working through some tutorials and making some spindles...I've noticed that there is some vibration and I'm not sure if this is a problem or not? I have all my tools laying on a shelf below and they all move and start jingling together. If I put my hand on the headstock or bed bars then I can feel a strong vibration. This may of course be totally normal with this type of lathe?

I've been trying to see if I can improve matters but not making much progress.

If I loosen the drive belt then the motor is very smooth. Once I put the belt back on the vibration starts. If I run the belt very loose (just tight enough to turn the headstock unloaded) or very tight (and I mean really tight) then the vibration is better. I've adjusted the head bearing and ensured there is no play there but haven't yet checked the bearing at the other end, could this be the problem?

I thought I'd try some weight on the stand so placed a couple of paving slabs over the bottom stand cross pieces, this stopped the vibration on those bars but didn't seem to help the lathe much. Mind you the paving slabs didn't sit that well on the bars. I tried some rubber under the paving but this made it much worse. Perhaps sand bags would be better at damping?

Is bolting it down the only answer? Any suggestions would be much appreciated.

edit: I've removed the chuck to eliminate that.

 

[Robbo3]

As the headstock is inboard of the legs then it's not likely that the overhaning bars are a cause for concern.
As everything runs smoothly until the belt is engaged I would look at the pulley alignment - if it's adjustable.

 

[Tris]

Hopefully one or two of the others on here with an engineering background will see this soon, but in the meantime here's a couple of things that have helped me with a similar record lathe.
Does the vibration occur in all the speeds or only one? If it is only in one range then it may be the frequency at that speed and bolting it down may help.
Sandbags would be better at damping the vibration but I think there will be more to do to find the cause before you start needing them.
I'd take a look at the bearings and also check the headstock spindle to see if it is straight. If you have access to a run out gauge you might be able to do this in situ.
Hth

 

[RichardG]

Thanks for the ideas, just heading out to check these items. Unfortunately I don’t have a run out gauge, keep meaning to get one but never got round to it.

 

[Lazurus]

check the alighnment of the head and tail stock as they can be out of alighnment, I have a heavy VB36 350 kg and sometimes get vibrations usually I dial the speed up or down untill it stops usually on bigger bowls though.

 

[minilathe22]

It could also be the spindle pulley is loose on the spindle, it is most likely held in place with a grub screw?

 

[Blister]

Have you taken the belt of and run the motor on its own ? If that runs smooth it can only be in the headstock

 

[clogs]

for the vibes you describe, something is really out of wack...
as blister says if the motor is smooth then its just the headstock......
the h/stock shaft and pulleys would normally be without any special balancing from the factory......
with the motor and belt disconnected does the shaft in the h/stock turn easily and smooth......?
any noises, grumbles or growels to indicate bearings....or rattles......?
I'm suprised the bearings are adjustable at that level of machine but I'm not conversant with it....just generalising ....
does it say in the manual to adjust bearings .....?
why did you think it was necc....?
I would have said that it had plain deep groove ball bearings fitted as standard.....no adjustment needed, at least shimmed out at the factory....
no point in going into design details with this.....
so try the above and let us know what you find please..these are very simple machines.....
as an add on, you normally accept them kinda vibes when you just start a project....ie. lumpy wood.....
then you need extra weight and or bolts to keep the lathe from scrabbling across the floor....

 

[RichardG]

Some progress hopefully.

The motor runs quiet and smoothly on its own. The vibration also got worse at the faster speeds.

I have an engineers stethoscope so I probed round the bearings and the back one sounded noisy. So after much cursing I’ve removed the spindle and rear bearing and ordered a replacement SKF version. The bearing doesn’t feel that bad now it’s off but thought I may as well eliminate it. The cursing was Records policy of putting two grub screws on the pulley, the first to lock onto the spindle then a second one to chew up the head of the first! I guess this is a safety issue but wouldn’t a bit of loctite be OK? I had to taper a hex key slightly so I could get it started and then knock it home!

The other thing I noticed was the spindle pulley seemed to have a bit of play in it even through the grub screw was really tight. It was difficult to access in the lathe but I’m sure I could see a tiny movement between the pulley and spindle. Other jobs have now stopped play but I’ll check it out on the bench on Saturday when hopefully the new bearing is here.

The front bearing is a tapered phosphor bronze variant and appears to be in excellent condition and well lubricated.

I was given the lathe and it has been standing in a unused workshop for many years, the chisel and bare metal parts were all rusty. The rear bearing should have had a rubber bung to seal it in but this was missing so there is a chance that some damp got in.

 

[Lazurus]

Good job, hope that cures it and you can enjoy the dark art of turning

 

[MusicMan]

I have an even earlier version, the Coronet No. 3 from which this descends.

The front taper bronze bearing should be adjusted to take up the end play in the spindle. Usually, tighten it till it locks then back off 1/4 - 1/2 turn, then tighten locknut without shifting the bearing adjust nut.

If the back bearing had lost its seal this could well be your problem, so the new bearing should fix it. Just the front bearing after fitting the new one.

What happens at the tailstock is important but totally irrelevant to your problem.

 

[minilathe22]

If the spindle pulley has some dirt inside, then it may not be locked solid with the grub screw. Make sure its clean before assembly and loctite on the grub screw, hopefully you can be sure its well seated. However it does sound like your bearing was the issue on this occasion.

 

[RichardG]

So, I fitted the new bearing today kicking myself for not getting a new drive belt whilst I had it apart. It has improved things, certainly the drive belt tension now makes no difference nor does changing the speed. The rear bearing grumble has also gone so all good. I also found the overhanging bars were vibrating so I damped them down with a round of steel.

There is still vibration but I have no idea how smooth these lathes were from new so may be I have too higher expectation and this is normal. can any other CL3 owners comment?

Certainly it’s more than good enough for me whilst I learn.

 

[MusicMan]

Did you adjust the front bering at the same time?

 

[RichardG]

Did you adjust the front bering at the same time?

Yes, you have to set up the front bearing once you’ve removed the shaft. I ran for the 5 minutes advised in the manual and then rechecked, all good.