slight wobble....

[arcos]

Oh, oh my lathe has developed a slight wobble at the headstock. 

I use a Nova G3 chuck and have run the lathe at various speeds to check this wobble. There is no perceptible movement at high seed. Low speed there is a clear wobble.

I have removed the chuck and given it a check over and a good clean and retried. Still the same.

I have run the lathe up with no chuck and cannot see any perceptible movement, though I guess that would be difficult with just the spindle showing.

I have removed, cleaned and returned the headstock locking nut, no change.

I have pulled and pushed on the headstock spindle for any perceptible movement, nothing.

Any suggestions please guys???

Oh, no I dont have access to one of those clever roller devices for checking bearings

[arcos]

Thanks George, very helpful...

[woody]

What lathe have you got because some lathes you have to adjust the bearings

[arcos]

It's a cheap Chinese lathe MC-940 unlikely to have a bearing let alone adjustable! 

I  just checked the pulley on the spindle and there appears to be slight movement but would not expect it to be creating a wobble on the chuck although I will tighten this up tomorrow and see what happens.

I'm a bit reluctant to start looking around for the bearing but maybe that will be my next step. When I start taking things to pieces I always have bits left over!! 

Mind you, if I were a neurosurgeon I would be difficult to find anything let alone have something left over with some forum members here! 

[woodndesign]

It's a cheap Chinese lathe MC-940 unlikely to have a bearing let alone adjustable! 

I  just checked the pulley on the spindle and there appears to be slight movement but would not expect it to be creating a wobble on the chuck although I will tighten this up tomorrow and see what happens.

I'm a bit reluctant to start looking around for the bearing but maybe that will be my next step. When I start taking things to pieces I always have bits left over!! 

Mind you, if I were a neurosurgeon I would be difficult to find anything let alone have something left over with some forum members here! 

  ....    ....    ....     ....  or ROFL ...till cry ...

Arcos, even cheap Chinese Lathes have a bearing/s, as Woody asked, if we could identify a type or brand, as most all lathes today at the entry end of the market come from China, it would help sort your problem as to what or if something could be done, at the moment it is for you to try all the options as you've been doing.

Cheers  David

[arcos]

 

Sorry David, I thought I would keep up the frivolity a little bit with the bearing comment.

The only thing it says on the lathe is MC-940 Wood Turning Lathe... Thats it!

Here's a link to the 'family' of lathes, although the design seems to have changed a bit!

http://www.jl-supply.com/product/page2/tools_9-2.html

I put a faceplate on and spun that up. Runs fine at every speed except 500rpm where it has a visible wobble.

Don't get me wrong it is NOT horrendous but I do need to get it sorted out... If I can't find anything obvious then I will have a try and packing the bearing with grease and see what happens. Has worked for me before so you never know, not on a lathe though.

[Bryan Milham]

If you are only getting it at one speed or loading, I'd first suggest you open the hatch or whatever you can and tighten everything in sight. Also ensure the pulley block is fully tightened against the headstock spindle.

It's probably retained by a Grub screw buried deep in a hole on one of the pulley diameters, so you may need to move the belt to find it.

[woody]

Sometimes there is a grub screw under another grub screw or the pulleys  could be out of alignment

[woodndesign]

Ah, thanks Arcos, that helps to make it a little clearer, yours is the bottom of the picture, you've mentioned the loose pulley and Bryan has rightly mentioned the Grub screw location, be where there could be two, the first outer screw will lock one which is underneath, it would be to release the screw first before trying to tighten and if you find it won't lock the pulley, it's then there's the second below, before tightening the lower one, check the pulley alignment as it could have moved, recheck once tightened, as the screw may pull into a different locations due to wear by the pulley having been moving on the shaft.

Lets believe this is all that is wrong.

Cheers   David

  ...  now why didn't I get straight to the point as you had done Woody ...

[arcos]

FANTASTIC!

Thanks guys...

There is definitely a little movement on the pulley block, not much but enough to make me want to tighten something! Two grub screws are there so will take the assembly off in the morning, clean, grease grub screws, refit and tighten.

I hope that will resolve the issue!

Great minds there guys! I'm sure I would have some bits left over with your three!!!! 

[Bryan Milham]

The 'Hive Mind' strikes again!

[woodndesign]

FANTASTIC!

Thanks guys...

There is definitely a little movement on the pulley block, not much but enough to make me want to tighten something! Two grub screws are there so will take the assembly off in the morning, clean, grease grub screws, refit and tighten.

I hope that will resolve the issue!

Great minds there guys! I'm sure I would have some bits left over with your three!!!! 

If this is not too late .. do not grease the screws, even if it's just them, any heat transfer can melt it and result even if a small amount getting into the pulley and onto the belt should it be running in that ratio at the time or later and effect the belt, if not cause it to slip.

Should you be able to grease (LM Grease) the bearing/s that the cage is open, use about a teaspoon (don't place in your tea) amount round the inside of the race, and not pack the outside, forces, it always finds it's way out not in ... over packed will effect the Coefficients of the bearing, fly everywhere and for our work pull in dust,  be careful in disturbing the seals if the bearing/s are sealed for life, they are just that ...    .. for life or till worn out ...      ...

If you've pulled everything apart,  ...  check the key is located in the shaft and not dropped out on assemble, the screw alone will not take the drive.

Cheers   David

[arcos]

Ok, removed pulley, cleaned, tightened grub screws and seems to be running MUCH better but still not completely true. I can feel a very, very slight wobble when sanding a test piece BUT it looks pretty true around the rim so hopefully this has cured it sufficiently.

I think that I will need to seriously consider a replacement lathe at some point but PLEASE not right now!!

Thanks for all the help and tips guys!

[woodndesign]

Well done, how did the bearing/s look ... Plan for the worst, trust for the best.

 happy turning.

David

[arcos]

Thanks David

To be honest I didn't even look at the bearing/s.

I prefer to try easy things first and if no success delve deeper!

Turned a little 'thing' with thin sides to see if there were a noticeable runout. I couldn't notice anything nasty so will leave it as it is for now.

I have a few olive bowls to turn tomorrow so let's see how that goes.