A look at the Clarkson Mark1 Spindle Bearings






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Please correct me if any information on this page is wrong. I'm no engineer and pretty much rely on my own judgement, be it right or wrong.
After fitting a quiet 3 Phase motor the Clarkson was still noisy in operation. The noise could only be coming from the spindle housing so I decided to take a look.
Thanks to Matthew Tinker for help on the bearings.

The markings on the bearings in my machine, going clockwise, are: 'ENGLAND - R&M - MJ 7/8 - 48 - 97DG'

The 'MJ 7/8' indicates they are 'deep groove unshielded standard ball bearings'. They can be bought cheap, and you can get them from lots of places.
'MJ 7/8' is equivalent to 'RMS7' and is a 'medium' inch bearing.

'MJ 7/8' or 'RMS7':-
ID=7/8th inch, 22.225mm
OD=2.25 inch, 57.15mm
WIDTH=11/16th inch (0.6875 inch), 17.463mm
Some bearing suppliers show the width for this bearing as 9/16th inch (0.5625 inch) so it is best to measure the bearing before ordering.

One bearing manufacturer states:-
MJ7/8 = max 13500 RPM
MJ7/8 2RSR = max 8500 RPM
The 2RSR version indicates 2 rubber seals. The speed is reduced on the sealed versions.

So, you may be able to run a Mark1 at 6000 rpm, like the Mark2 (as long as the grinding wheel is suitable).

 



↓ I removed the two screws that secure the Bearing Cover on the grinding wheel side of the spindle.
The bearing looks like a normal Ball Bearing to me, but I could be wrong.
I smeared a small amount of LM grease into the race, taking care not to overpack the bearing.
Oil or Grease?. It looks like oil will run out of the spindle housing, so the bearing has to be greased.
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↓ There are two grooves in the Bearing Cover where it contacts the spindle.
Maybe these grooves go some way to prevent grit passing the cover and getting into the bearings.
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↓ I removed the socket set screw that secures the pulley to the spindle.
The pulley was a tight fit on the shaft so I had to use a Puller to remove it.
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↓ I removed the socket set screw that secures the spacer/retainer (?) to the spindle.
After removing the screw I found the spacer was a tight fit. I then realised that I did not have to remove it.
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↓ I removed the two screws that secure the bearing cover on the pulley side of the spindle.
The bearing looks like a normal Ball Bearing to me, but I could be wrong.
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↓ I smeared a small amount of LM grease into the races, taking care not to overpack the bearing.
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↓ MARK 2 Here are a couple of pictures of the Mark 2 spindle.
Many thanks to Ken Widdall for supplying the pictures and information.
Ken says "This is the head of the Mark 2, you can see the bearings. I am sure on the Mark 1 there is one bearing at each end but on the Mark 2 there is a needle bearing and a ball race."
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↓ MARK 2 - It looks like that retainer/spacer unscrews once the socket set screw is removed?
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↓ MARK 2 - needle rollers
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↓ Fascinating bearing manufacture video.

 

 





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