7×12 Bearing Spacer

[woody1Participant @woody1]

CL300M

[woody1Participant @woody1]

Evening all, hope we'll and safe,

Would any of you kind gentleman know the dimensions of the spacer between the rear bearing and c-nut's (Clarke cl300m) I bought my angular contacts (thanks again ARC) but I really want to make a new spacer. The one on is plastic and is also bulging quite visibly at the c-nut end.

I have made some measurements, bore 30mm based on the inside diameter of the new bearings, outside 38.70mm and length 30mm. I want to get it right to avoid taking the machine apart multiple times.

Thanks,

Woody.

[Clive Brown 1Participant @clivebrown1]

Hi Woody, I don't know your lathe at all but angular contact bearings are frequently set up with a "spring" arrangement to apply a defined pre-load to the bearings to make for a stiffer spindle. As such, your plastic spacer might be intended to collapse as the C-nut is tightened to provide this pre-load. A specific length can't be specified.

Cue all cl300m experts.

[woody1Participant @woody1]

Thank you for the reply,

Cue all cl300m experts.

I actually found a pair of suspension springs the other day whilst walking the dog and brought them home. Bloody litterers I could go nuts.

[Neil WyattModerator @neilwyatt]

My experience:

Now remove the locknut and thread on the bull wheel, it will be apparent that the bull wheel no longer lines up with the tumbler reverse. I had to shorten the spacer by 4mm, which I did in the lathe, relying on friction to hold the rear race in place against the light load. Once shortened I had to use a rat-tailed file to enlarge the notch in the spacer for the end of the bull-wheel key, before replacing the rear bearing shield, fitting the key and bull wheel. I then refitted both lock nuts and re-tightened the mandrel. Appropriate preload for a roller bearing this size and precision application is very small, of the order of zero to four thous. The pitch of the mandrel thread is 1.5mm or 60 thou so, once all shake has been removed with the first locknut, tighten it by no more than a further 24 degrees and lock it securely with the second nut.

[Howard LewisParticipant @howardlewis46836]

Thank You Neil.

Have been wondering what the pitch of the thread was, but too lazy to check

So the preload can be applied by marking a gear tooth and the first nut and then tightening the nut by a tooth or two on the gear,, before locking with the outer nut.

Should have made my mandrel extension (To carry any swarf outside of the gears, ) a screw on fitting, rather than a clamp on.

Another item on the Round Tuit!

Howard

Edited By Howard Lewis on 12/11/2020 12:59:20

[Neil WyattModerator @neilwyatt]

These might be helpful;

Parting Off on Mini Lathes and Bearing Choices

Changing the Bearings on a Mini Lathe

Slightly updated versions of my articles written about 15 years ago!

Neil

[Andy_GParticipant @andy_g]

Posted by Neil Wyatt on 12/11/2020 13:41:09:

Slightly updated versions of my articles written about 15 years ago!

Neil

Very interesting – I've not been able to find (m)any objective before / after assessments of the effects of bearing replacement.

If you were to do it again, would you go with angular contact or taper roller?

[Andy_GParticipant @andy_g]

Posted by woody1 on 11/11/2020 20:14:02:

I bought my angular contacts…

Posted by Neil Wyatt on 12/11/2020 11:36:06:

…I had to shorten the spacer by 4mm…

Just checking – if woody1 is fitting A/C bearings, there shouldn't be any need to shorten the spacer, should there? The A/C bearings are supposed to be the same width as the originals, I believe.

Just re-make in metal to the existing dimensions? (My 7X lathe is a different make with a brushless motor, or I'd offer to measure the spacer!).

[woody1Participant @woody1]

Cheers for the replies, just to clarify I have angular contacts from arc. I machined a spacer 30mm x 39m x 31.5mm. if doesn't fit its not the end of the world. I'll let you guys know for a future reference if needed.

Thanks,

Woody.

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