Novice with lathe problems

[danm182]

Hello everyone, I'm new to this forum, and woodturning and would like to learn more about my new hobby. I've got a Clarke 37inch lathe that I bought second hand a few months ago, and been having a play with it regularly.

However, a few days ago when I was trying to turn a bowl, the belt wouldn't turn. After some amateur investigation of the motor, and changing the belt to a slower speed, it very slowly started to turn. If I pull the motor forward, making the belt slacker, it starts to spin faster, then I let the motor back to it's original position, and so the lathe will function correctly.... until it is switched off, and I have to do it all again.

It's not a major issue, as I can still get it working, although not to the highest speed.

Does anybody have any idea as to why it's doing this, and how I could fix it?

Thanks!

Dan

 

[jumps]

welcome Dan

always difficult to diagnose from a distance, but two possible things strike me up front -
1. the headstock bearing is tight/corroded/lacking lube or something similar - don't know the particular set up on that lathe so I can't be more specific. if the issue is related to this, I would expect significant heat build up in this area after it's been 'got going' for a while.
2. power supply issues - the motor isn't getting the amp's it wants from your supply. might result from a long extension of too small a rating?

I'm sure others will have more, and someone might be able to clarify the lubrication to the headstock as well

edit - looks like the headstock spindle runs in a pair of sealed ball bearings. No lubrication there.

I would remove the belt/ de tension it and then turn the headstock spindle by hand - should turn easily and smoothly. If the problem is here you can get new bearings from Clarke (part nos in manual) or remove and note the codes to get from a bearing supplier.

 

[Jonzjob]

Twos up for Jumps jumping to probably the right conclusion :mrgreen:

Try, as Jumps said, turning the headstock bearing with no tension on the belt. If that turns freely then try to turn the motor while the belt is loose and note the force it takes to turn the motor and then apply the correct tension to the belt. Then turn the headstock bearing and it should be pretty well the addition of the two. If not then it could well be that the headstock bearings are worn.

Sorry, not a very good explanation?

 

[jurriaan]

A possibility that occurs to me is that your motor uses a starting capacitor, and it's shot. That means the motor has almost no torque when starting, and that describes your problem rather well. In that case, the spindle should turn smoothly by hand, and once the motor is up to speed, you should be able to turn normally.

The starting capacitator can be replaced of course - a decent motor repair shop can do that for you.

 

[TEP]

A possibility that occurs to me is that your motor uses a starting capacitor, and it's shot. That means the motor has almost no torque when starting, and that describes your problem rather well. In that case, the spindle should turn smoothly by hand, and once the motor is up to speed, you should be able to turn normally.

The starting capacitor can be replaced of course - a decent motor repair shop can do that for you.

I would go with jurriaan, sounds just like a capacitor failure. A new capacitor should cost no more than a tenner, and easy to fit yourself. Just take off the small cover on the side of your motor. Machine Mart can sell you one, or look around online once you get the spec.

 

[danm182]

Thanks everyone, I did have a suspicion that it might be something to do with the capacitor. I'll see what I can do. Thanks again!

 

[Deejay]

Morning Dan

A simple test for the starter capacitor.

Remove/loosen the drive belt so there is no load on the motor.

Fingers out. Switch it on.

If the motor runs up to speed it's not likely to be the capacitor.

If it doesn't, spin the motor by hand. If it runs up to speed with a 'push' start, it probably is the capacitor.

Bob (9fingers) is the resident motor expert here so you might like to search his posts for more details and cheap suppliers.

Cheers

Dave

 

[danm182]

Thanks Dave. I tried this and having taken off the belt, the wheely things spin. The headstock seems OK, no dodgy noises that indicate the bearings are alright. However, the tension of the belt seems to be what is really causing the issue - if it's on a slow setting, with the belt at a seemingly less tighteness, it works. When I move the belt up to a faster setting, the belt seems to be too tight to want to move and the motor just hums.

So, having read everyone's input, would I be correct in thinking I need a new capacitor? The above post by jurriaan would seem to suggest so....can somebody confirm this please if they understand my ramblings?!

Thanks!!

 

[NikNak]

Is it a variable speed lathe via a lever..?

Left to slow down, right to speed up..?



Nick

 

[danm182]

Is it a variable speed lathe via a lever..?

Left to slow down, right to speed up..?

Hiya Nick,

to change the speed I have to swing open the guard and take the belt off by hand - it would appear my lathe is quite old!

 

[Tinbasher]

"When I move the belt up to a faster setting, the belt seems to be too tight to want to move and the motor just hums. "

Are you loosening the motor mount to move the belt or just forcing it across? It should be adjusted to the same tension regardless of the speed not just forced across. It isnt safe to assume that the belt tension remains the same for each set of pulleys.

 

[Jonzjob]

On my CL1 before I changed to a 3ø motor if I needed to change the speed I had to loosen the motor on its swivel to take the tension off the belt and tighten it to stop it taling the belt pressure again, change to the different pulley setting, loosen the motor again and let the weight of the motor take the tension of the belt. Then turn the motor back on at the new speed.

 

[Deejay]

Morning all

If the motor spins up, the capacitor is probably OK. before you start changing bits, I think Tinbasher has got the answer.

Is this the lathe ?

http://www.machinemart.co.uk/download/CWL12D.pdf

Looks like the belt might need retensioning if you change speed.

Cheers

Dave

 

[danm182]

Morning all

If the motor spins up, the capacitor is probably OK. before you start changing bits, I think Tinbasher has got the answer.

Is this the lathe ?

http://www.machinemart.co.uk/download/CWL12D.pdf

Looks like the belt might need retensioning if you change speed.

Cheers

Dave

Yes! This is my lathe! However, when I alter the tension on the belt when it's on it's highest speed setting, still nothing happens. I think I'm doing it right by moving the motor forward and backwards, as the manual says, but it doesn't seem to help at all. Or am I doing it wrong?!

 

[TEP]

However, a few days ago when I was trying to turn a bowl, the belt wouldn't turn. After some amateur investigation of the motor, and changing the belt to a slower speed, it very slowly started to turn. If I pull the motor forward, making the belt slacker, it starts to spin faster, then I let the motor back to it's original position, and so the lathe will function correctly.... until it is switched off, and I have to do it all again.

Dan

Looking back at you original post, if the spindle turns OK without the belt, and the motor turns by hand OK without the belt, then I still say it is the capacitor. Single phase motors need a real kick to start them off, and in the correct rotation. In fact the starting current load can be almost double the running load.

This is why I believe when you turn the motor by hand with the power on you are acting as the capacitor. As you say once running it is OK until you switch off then have to go through the whole routine again. Try this video for explanation.

Also as an aside, IME these lathes have no real belt tensioning gear, they rely on the weight of the motor resting on the belt for tension. When I used one many years ago one trick was to fix a block of lead to the motor top to give it more weight to drive a large piece of work, with no belt slip.

If the belt is too tight at any position I believe there is a bolt and nut on the motor platform, this may be stopping the motor moving far enough to move the belt easily.

 

[Deejay]

Morning all

Dan

you said above

I tried this and having taken off the belt, the wheely things spin.

Does the motor turn and run up to speed without you touching it when you switch it on?

Cheers

Dave

 

[gerrybhoy70]

Just a bit of tuppence-worth from me.
I have a similar set-up lathe with the manual belt change for drive speed, and had a similar issue recently.
The main issue was the belt tension. It had tightened during the cold weather (expansion/contraction??) so I let out a little bit of the tension on it and the problem went away.
Might just be worth a try - and could save money on new bearings or capacitor.

 

[danm182]

Dan[/quote]

Looking back at you original post, if the spindle turns OK without the belt, and the motor turns by hand OK without the belt, then I still say it is the capacitor. Single phase motors need a real kick to start them off, and in the correct rotation. In fact the starting current load can be almost double the running load.

This is why I believe when you turn the motor by hand with the power on you are acting as the capacitor. As you say once running it is OK until you switch off then have to go through the whole routine again. Try this video for explanation.

Also as an aside, IME these lathes have no real belt tensioning gear, they rely on the weight of the motor resting on the belt for tension. When I used one many years ago one trick was to fix a block of lead to the motor top to give it more weight to drive a large piece of work, with no belt slip.

If the belt is too tight at any position I believe there is a bolt and nut on the motor platform, this may be stopping the motor moving far enough to move the belt easily.[/quote]


Thanks Tam - that video explains exactly my issue. I did buy a new capacitor the other day, so I'll get it fixed in and see what happens. If no change, I'll have a look at the nut on the platform and adjust that.
Thanks,

Dan

 

[danm182]

Morning all

Dan

you said above

I tried this and having taken off the belt, the wheely things spin.

Does the motor turn and run up to speed without you touching it when you switch it on?

Cheers

Dave

Thanks Dave,

Yes it does, but only when the lathe is set to a slow speed, OR when the belt is not attached at all. It seems that the motor isn't strong enough turn with any real weight or resistance upon it.

Dan

 

[danm182]

Just a bit of tuppence-worth from me.
I have a similar set-up lathe with the manual belt change for drive speed, and had a similar issue recently.
The main issue was the belt tension. It had tightened during the cold weather (expansion/contraction??) so I let out a little bit of the tension on it and the problem went away.
Might just be worth a try - and could save money on new bearings or capacitor.

Thanks Gerry,

I have tried adjusting the tension, but it's not really helped a lot. I've managed to get it working on a medium fast speed, which will do for now, but it doesn't solve the problem.

Thanks,

Dan