Myford S7 mkII – Clutch Bush

[Thomas GudeParticipant @thomasgude37285]

Hello again,

So I have upgraded to a mkII clutch and headstock that I found for a not terrible price and the machine is now running great! I do have a concern though that I would like to check. When assembling the belt guard and clutch I found this (photo). This is the LH bearing bush of the clutch.

Are the tracks on the inside the result of cr*p being caught in there and someone scratching away trying to remove the clutch spindle? Or are they intentional for some kind of lubrication spreading? It makes a bit of noise when work is being cut but nothing too concerning. Should I be worried, can I live with it or is it part of the design..? It does look odd.

Cheers

[Thomas GudeParticipant @thomasgude37285]

Abused or intentional?

[Clive HartlandParticipant @clivehartland94829]

It does look like a machined set of grooves for lub. I see the oil pot on the side, does the hole line up inside with the grooves?

Clive

[Martin KyteParticipant @martinkyte99762]

They should be oilite bushes I think. When I changed mine that is what Myford sent me as replacements. The originals had holes but they seemed to be drilled by a previous owner.

regards Martin

[Thomas GudeParticipant @thomasgude37285]

I believe the tracks do coincide with the oil hole but not all of them are connected to each other. Is this what you have on your machine Martin?

[RobboParticipant @robbo]

The original bushes are Oilite, as Martin says, and are not drilled for oil as they are oil soaked and permeable

 However, people being people they often drill holes in them to coincide with the oiler – this results in all the oil running straight out of the oiler and through the bearing instead of soaking gradually through.

They should be smooth inside.

This looks to me as though someone has removed the shaft, which has a burr or other sharp protrusion on it, and these score marks are where they have wiggled it to and fro, no doubt grasped firmly in a Mole wrench.

Phil

Edited By Robbo on 03/03/2014 19:27:38

[Martin KyteParticipant @martinkyte99762]

I agree with Robbo.

Sintered (oilite) bushes do not need oil holes. It sounds like someone has not really understood what is going on and done a mod. New bushes are cheap enough if you want to go to the trouble of replacing. I don't know if running oilite bushes for years and years eventually closes up the pores on the bearing surface. I know they suggest you do not ream such bushes for just this reason. If this is the case then eventually you could see a situation where lubrication was inadequate and I suppose someone may choose the cheap way out instead of bush replacement.

My undrilled oilite bushes soak up the oil in the oil cups at a fair rate so I am perfectly happy that the oil is getting where it should.

regards Martin

[Thomas GudeParticipant @thomasgude37285]

Exactly my suspicions Robbo! The oil cup is pretty hungry compared to the others. I can live with as long as it's not doing any damage or affecting the accuracy or strength at all.

Thomas

[Mike PooleParticipant @mikepoole82104]

A new bush is available from Myford, if the shaft is still in good condition I think I would replace the damaged bush.

Mike

[RobboParticipant @robbo]

If it were me, I would replace both bushes – but then I'm a picky old sod. Not done this on a S7, but on the ML7 was a simple job, just needed a drift/mandrel turning to size and they were easily driven out and the new ones in.

The downside of the scored bush is that the bearing surface has been much reduced, so it will wear quicker, may already be a bit oval, bearing (no pun intended) in mind that the shaft is pulled to the lower side by the tension in the drive belts, especially the countershaft to headstock belt. Would probably cause some vibrations if worn.

The upside is that it could be said that the scorings act as an oil reservoir and the hole drilled through keeps them filled up..as long as the oil cup is kept full.

Phil

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