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, which is not always right.
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.
I did not go as far as removing the bearings because I did not know how to at the time. I was wary of causing damage.

Since initially writing this page, I have received a diagram from Peter Selby and that explains the bearing removal procedure.
My spindle is very noisy and I must have a go at replacing the bearings when I get time.
Peter mentioned that after replacing his bearings, the spindle was still rather noisy for some unknown reason. He dealt with the noise problem by wearing ear protectors, and turning up the radio!

Thanks to Matthew Tinker, Ken Widdal, and Peter Selby for help and information on the bearings.




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SPINDLE ASSEMBLY


↓ Peter Selby was kind enough to send me the following image, which shows the Clarkson Mark 1 spindle arrangement.
I am not sure if this image is of the actual Clarkson spindle assemby, but it looks pretty similar indeed?

The bearing in the image is referred to as a HOFFMANN MS 9.
I looked up the HOFFMANN bearing and found the dimensions were 7/8" ID, 2 1/4" OD, and 11/16" width, and these dimensions correspond with those of the Clarkson bearings.
The HOFFMANN bearing I found was 'very' expensive!

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BEARING SIZE


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).

 


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INSPECTION AND GREASING


↓ On the grinding wheel side of the spindle, I removed the two screws that secure the bearing cover (retaining cover), and removed the cover.
The bearing is unshielded.
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.
There has been talk of putting oil into the threaded hole in the top of the spindle housing, but that is not the way to go!
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↓ On the grinding wheel side of the spindle, there are two grooves in the bearing cover where it contacts the spindle.
I do not know what the grooves are for. Maybe these grooves go some way to prevent grit passing the cover and getting into the bearings?
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↓ On the pulley side of the spindle, 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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↓ On the pulley side of the spindle, I removed the socket set screw that secures the adjusting collar on the spindle.
At that time I did not know what the collar was for.
I now know that the collar is an adjusting collar, and is used to secure the spindle, and to adjust the end play.
After removing the screw I found the collar was a tight fit. The collar is screwed onto the shaft.
I left the adjusting collar alone as I did not need to remove it to look at the bearing.
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↓ On the pulley side of the spindle, I removed the two screws that secure the bearing cover (retaining cover), and removed the cover.
This exposed part of the bearing.
You can see the set screw has been removed from the adjusting collar.
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↓ I smeared a small amount of LM grease into the race, taking care not to overpack the bearing.
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MARK2 SPINDLE


↓ 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 - The adjusting collar can be unscrewed once the socket set screw is slackened.
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↓ MARK 2 - needle rollers
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