ML7 lost drive

[AJWParticipant @ajw]

Using my ML7 this afternoon turning at a large diameter the chuck stopped. This is usually caused by the mandrel belt slipping as I don’t have it that tight, but it wasn’t, the belt/pulley was still being driven!
It would appear that the stepped mandrel pulley drives the smaller (brass) gear I am guessing that there is an interference fit within which has now failed (been ok for the last 60 years!)
Obviously a strip down is on the cards and I’m guessing the drive could be restored possibly with ‘loctite’?
Anyone else encountered this problem?

Alan

[AJWParticipant @ajw]

[JasonBModerator @jasonb]

Few similar posts like this one will help

[AJWParticipant @ajw]

Thanks for that, it is as I suspected, no longer enough of an interference fit!

Alan

[John OlsenParticipant @johnolsen79199]

I had that happen on my ML7 some years back. It does not help that the standard V belts make the alloy pulley run quite hot. I ended up changing it over to a poly V belt. While I was about it I made a four step pulley instead of 3. Hemingways have a kit for ploy V belt to a Super 7 but that is not applicable for an ML7. Maybe I should write up what I did.

John

[AJWParticipant @ajw]

Thanks John, I agree the pulley does run warm and perhaps with the warmer weather it took it beyond the point of no return! I can still use it on ‘normal’ stuff but working on a 3 inch diameter highlighted the problem.

Alan

[AJWParticipant @ajw]

Dismantled the headstock today and had to heat the pulley to get it off the gear – it was still a good fit!
All cleaned up and degreased then assembled with Granville ‘bearing fit’
Seems to have done the job, time will tell!

Alan

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