Clarke CL250M Spindle too Stiff?

[Ian MellorsParticipant @ianmellors72388]

I've noticed that the chuck seems harder to turn than it should be, so I removed the timing belt from the motor and pulled the lead screw gears out of engagement with the spindle gear and the chuck/spindle still does not rotate freely.

When I say not freely it turns ok, but there is resistance. It will not spin by itself.

Is this normal? if not, I guess it's time to remove the spindle or adjust bearings? I'm pretty sure they are taper bearings, so maybe up too tight?

Edited By Ian Mellors on 05/03/2021 09:14:08

Edited By Ian Mellors on 05/03/2021 09:25:37

[Ian MellorsParticipant @ianmellors72388]

[David George 1Participant @davidgeorge1]

Is it a new machine, and is if very cold where you are, as it may change with temperature. Just a thought.

David

[Ady1Participant @ady1]

Does sound that way

They might be knackered, a sign of knackered roller bearings is resistance when turned by hand

Hope I'm wrong

[Ian MellorsParticipant @ianmellors72388]

Not new, 15 years old but has had very little use. It's in a pretty stable cool location (insulated loft space). If they are shot it's no biggie as spares are only a fiver each from ARC. I guess a strip down might be in order?

[Brian WoodParticipant @brianwood45127]

Hello Ian

I would try easing the preload a trifle so that the bearings are nipped rather than pulled up harder as your description implies. Then you can make a judgement on whether they sound noisy on running and act accordingly

Regards Brian

[Ian MellorsParticipant @ianmellors72388]

Posted by Brian Wood on 05/03/2021 10:35:44:

Hello Ian

I would try easing the preload a trifle so that the bearings are nipped rather than pulled up harder as your description implies. Then you can make a judgement on whether they sound noisy on running and act accordingly

Regards Brian

Thanks Brian, I'll try that over the weekend

[Ian MellorsParticipant @ianmellors72388]

No such luck Brian, looks to me that the whole rear bearing at least is solid. Looks like the whole bearing is rotating in it's seat. Needs a bit more stripping down to get them out. Job for another day…..

[Ady1Participant @ady1]

At a fiver a pop I'd do both bearings and get 2 spares

[Brian WoodParticipant @brianwood45127]

Hello Ian,

Thank you for the feedback, at least you will not be surprised by your findings, As Ady1 says, clearly the time has come to change them, they probably had too much preload applied right from the start.

It's easy to overdo it too, just enough to take out end float and then a bit more to the point where drag can just be detected on rotation. Back off a trifle on that and fix

Regards Brian

[Ian MellorsParticipant @ianmellors72388]

Posted by Brian Wood on 06/03/2021 09:16:42:

Hello Ian,

Thank you for the feedback, at least you will not be surprised by your findings, As Ady1 says, clearly the time has come to change them, they probably had too much preload applied right from the start.

It's easy to overdo it too, just enough to take out end float and then a bit more to the point where drag can just be detected on rotation. Back off a trifle on that and fix

Regards Brian

Let's just hope I can get them out…..

[Brian WoodParticipant @brianwood45127]

Hello again Ian,

I believe ARC have a procedure for pulling the spindles on mini lathes which would be helpful for you.

If they are as you suspect taper bearings, with the spindle out it should then be obvious how the outer races can be extracted from their pockets

Regards Brian

[Ian MellorsParticipant @ianmellors72388]

Thanks Brian, having taken several bits off to expose the rear bearing cover and not really succeeding in getting it out I gave the end of the spindle a good few taps with a hammer (with a block of wood over the end) and hey presto, it all freed off looks like you were right, over tightened at the factory.

All back together and running much better now, can get good slow speed running. Will give it a bit of a run to bed things in and recheck.

[Brian WoodParticipant @brianwood45127]

Hello again Ian,

That sounds like good news but I fear the episode may well have shortened the life of the bearings anyway. Roller bearings, by virtue of line contact, are more forgiving than ball bearings in the same situation, as the balls concentrate any overloading and indent the bearing race(s). The process is known as brinelling. In severe cases the bearing feels decidedly 'digital' as it is rolled round and corresponding flats will have formed on the balls as well. The life left in such a bearing is indeed short.

I would still take Ady1's advice and get a new set in from ARC, the investment is quite tolerable and then you have them ready for change at a time to suit you.

Regards Brian

[not done it yetParticipant @notdoneityet]

Looks like the whole bearing is rotating in it's seat.

If that was the case, it needs to come apart now, not later.

[Ian MellorsParticipant @ianmellors72388]

Posted by not done it yet on 06/03/2021 14:15:16:

Looks like the whole bearing is rotating in it's seat.

If that was the case, it needs to come apart now, not later.

That was my mistake, the outer race was behind the seal plate, all rotating as they should thankfully.

[Ian MellorsParticipant @ianmellors72388]

Posted by Brian Wood on 06/03/2021 14:05:40:

Hello again Ian,

That sounds like good news but I fear the episode may well have shortened the life of the bearings anyway. Roller bearings, by virtue of line contact, are more forgiving than ball bearings in the same situation, as the balls concentrate any overloading and indent the bearing race(s). The process is known as brinelling. In severe cases the bearing feels decidedly 'digital' as it is rolled round and corresponding flats will have formed on the balls as well. The life left in such a bearing is indeed short.

I would still take Ady1's advice and get a new set in from ARC, the investment is quite tolerable and then you have them ready for change at a time to suit you.

Regards Brian

Noted, I'll order some on next order with Arc. Looks like I need to remove the headstock and get the spindle pressed out. We have a press at work

[larry phelan 1Participant @larryphelan1]

Good sound advice there from Brian Wood, as always.

As Ady1 says, at that price replace the lot, they are for nothing !

[Ian MellorsParticipant @ianmellors72388]

Just received an order from Arc, was ordering something else so took the opportunity to order two spare bearings and a pair of motor brushes, amongst other things

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