Mk2 S7 headstock front bearing oiler plug missing grub screw

[Ken WeeksParticipant @kenweeks58536]

I have a MK2 S7 head stock that I am overhauling.

The oiler sealing plug A4770 no.72 on the exploded parts diagram is missing a grub screw.

Can anybody tell me the size and thread of the grub screw?

Ken

[Ken WeeksParticipant @kenweeks58536]

[davebParticipant @daveb17630]

I do not have drawings to hand but if you mean the plug for the wick and spring, the threaded hole is used to extract the plug, it's a blind hole, from memory, 4BA. Dave

[RobboParticipant @robbo]

Dave

you are right that the threaded hole is blind and is to take a screw so as to extract the plug, but the thread is 2 BA

So Ken, its 2 BA and long enough to thread into the plug and pull it out. And push it back in, it being a tight fit even without the 'O' ring on it.

 

 

Edited By Robbo on 24/03/2017 22:10:05

[Ken WeeksParticipant @kenweeks58536]

Thanks for the replies.

Mine is not a blind hole it has oil coming from it and I can push the felt up.

Thanks once again

Ken

[LambtonParticipant @lambton]

Ken,

The “grub screw / oil plug” you refer is to retain the tension spring A3611/1 which cannot be removed from the top end inside the front bearing bush. It also stops headstock lubrication oil from escaping. I have a new one in front of me purchased some years ago from Nottingham Myford and it measures 0.407” diameter so the plug must obviously be big enough to clear this spring. Also it has a groove to accommodate the O ring H73 (BS 011) on the drawing so it is clearly not just a simple grub screw. I do not have one to hand that I can measure but In line with Myford practice the thread is likely to be BSF probably 7/16”. Have you tried Myford for a spare? They do not list one on their website but they may still be able to help.

The dimensions of a BS011 O ring are: Cross Section: 1.78mm Inside Diameter: 7.65mm Outside Diameter: 11.21mm. Obtainable from any good bearing stockist.

The 2BA grub screw referred to by Robbo is the small one parallel with the spindle and just below it that enables a sharp, thin probe to be inserted whilst holding down the lubricating wick whilst replacing the spindle after a belt or bearing change.

I hope this is of some help.

Eric

[RobboParticipant @robbo]

Eric,

The screw we are discussing is not the grub that can be unscrewed to insert a needle to hold the wick, but one that screws into the end of the plunger that you describe. It seems to have no purpose other than to be screwed into the plunger in order to pull it out of the hole in the headstock. As you say, the plunger retains the spring, and so is a very tight fit.

Ken,

Yours seems an odd one. I have three of these plungers and all have a blind hole tapped 2BA. No idea why yours is threaded clear through. However, you don't need me to tell you how to proceed. But if you can't find a screw then drop me a line and I'll send you one (or 2) – but I no longer have your address .

[Author]

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