How do I, Check/clean cam lock spindles and backplates?

[Russ BParticipant @russb]

[Russ BParticipant @russb]

I just wondered how I should go about checking and cleaning up my lathes spindles and chuck backplates. (newly purchased lathe)

I have gently wiped around the spindle and backplate with some very fine brass wool and thin oil which has cleaned it up nicely as it was tarnished and gummy with crap, but there are a few marks and imperfections.

I've never been shown how to use engineers blue, it's never stopped me, but the stakes are a little higher now and so I'm hesitant to start attacking anything till I've had some sound advice if anyone would be so kind.

Many thanks,

Russ

Edited By Russ B on 28/03/2016 13:54:34

[Nick_GParticipant @nick_g]

.

If it were me I would just remove the gum and ensure that no tiny parts of swarf exist upon the spindle and chuck mating surfaces. gradually lock the cams up. (don't tighten one totally. Do it gradually like a cylinder head)

I would then just use it and see if a problem does actually exist before I did anything else. You could end up creating a problem yourself if you just jump in.

Nick

[Ian PParticipant @ianp]

I think that Engineers Blue would be described as being in the NDT (Non Destructive Test) category so you have no need to be hesitant. I suppose if you used too much it might create a slippy floor hazard but it not a real risk.

By all means check how well the various parts contact each other, but if everything is clean the camlock system holds spindle workholding accessories firmly, accurately and highly repeatable.

Ian P

[Tim StevensParticipant @timstevens64731]

In my view, there is a problem with checking stuff before you really know (a) what to look for and how much counts as 'bad', and (b) that there really is a problem to be resolved. You can do a lot of harm trying to 'correct' something which isn't actually out of order.

So, you apply blue and check a surface, only to find that it does not contact completely evenly all over. Does this mean you have to get to work with the scraper? You do know how to work a scraper, then, but you don't know about blue? And what if the surface you are going to 'attack' is actually the flat one, and the other part is slightly out of true? How will you tell? And how about the out-of-truth being due to the fact that there are other parts bolted to it, which themselves might be the source of the error?

No, you can clean and lubricate, and it does no harm to check that everything works properly, no stiffness or slackness, and find out what this row of little screws does, but I would go no further at this stage. Of course, you will do no harm applying blue, it is what you do about it, and the first thing is knowing whether what you find is significant, and so on. And if you do notice something which looks odd, ask. We're here to help.

Just my experience, of course.

Regards, Tim

[Russ BParticipant @russb]

Tim, it sounds like your echoing my caution thanks.

At this stage, all I've done is clean, apply blue to the spindle taper and register and gradually tighten round all 3 cams on one of my backplates (I have 2) What I found was a very, very even transfer to the register face, but a few imperfections on the taper. I'm just wondering how other people check.

I don't know if the issue is with my backplate or with my spindle, or if there is not an issue – hence the question how do I check. I'm just wondering how it should be done?

Edited By Russ B on 28/03/2016 17:02:08

[Tim StevensParticipant @timstevens64731]

What matters about the taper is 'does your tooling run true' – so fit eg a collet chuck and check the runout. Or a fairly new centre and see if the point runs true. If so, and the tools are held without any wobble, leave well alone.

The 'posh' way to check is to use a special mandrel – one end fits the taper and it has a long cylindrical bar made concentric with it. Any runout is exaggerated at the far end. But more expensive than you need, right now. Unless you live near someone who could lend you one?

Cheers, Tim

[Russ BParticipant @russb]

Tim thanks,

Sorry, I was referring to the external D1 camlock taper. It is the only thing that pulls the backplate concentric when tightening the cams and it has imperfections so I doubt it's running true.

I've thought about it, and if I simply mount a DTI and spin the spindle I'll easily see any high spots and I can take it from there with regards to what I should do about it.

I don't have any centres big enough (4MT) at the moment so I can't check the internal taper, I'm less worried as that's something I don't use much, and I don't image being easy to damage.

I have an 8 inch burnerd 4 jaw with factory integrated D1-3 system, so I image its outer body will be concentric to the D1 taper to a fairly high tolerance, so I could use that as a rough point of reference for assessment.

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