Colchester Student Index Ring

I have been trying all day to put this back together with no sucess, I have been able to get all three springs and two balls in place but not the third ball, can anyone advise on a method please?

Colchester Student mk 1 2 or 3?

It is a Mark 1 and a half (1 1/2 ) but I suppose the same principle would apply to other Laths, it is basically one ring inside another with three ball bearings and springs between the two to provide some tension.The problem is trying to hold the springs and balls in place in the smallwer ring to allow the larger ring to fit over the smaller ring.

I would get it all back together up to getting the third ball on place but do it all under a small press then when you find it all in place, except for the ring actually going over the third ball, apply a little pressure. Easier to show you than describe.

graham.

Machine yourself up a collar with taper that fits the inner part with an outside diameter that which the balls spring against. Put the springs and balls in their respective grooves, put the collar on the inner piece, push the outer piece over the taper, thus encouraging all three balls/springs to go into place.

Easy

Jo

Thanks for your reply Oompa, I thought of something like this I was going to use the vise to hold it the problem is that to get to the position of having the two balls in place and attempting to put the third one in the two rings are not parrallel and it is almost impossible or impossible to expose the hole where the third ball is to go without letting the other balls escape. I have been thinking of making some sort of narrow retaining ring to hold all the balls in place whilst I slip the larger ring partly over the balls and then removig the retaining ring and fully pressing the large ring home. There really is very little difference in the diameter of the two rings, there is a groove in the larger ring and the balls run in this groove when all is assembled.

John

Sorry Jo we where both posting at the same time just seen your post, yes these are the lines I was thinking about.

John

Jo, I am not fully with your method, this collar will need to be removed to allow the outer ring to go fully home will it not be sandwitched between the two rings.

John

Hi John,

When a spring and ball is in position does it completely push into a hole? I'm thinking you could maybe put all three springs and steel balls in position first and hold with fingers, then bring the collar over the top of them and squeeze in a vice if necessary. (You may have tried that already ) 

Cheers,
Ed.

Edited By Ed Duffner on 08/05/2014 09:32:36

It will not be sandwiched between the two rings as the larger ring will have slid into place on the smaller ring leaving the tapered ring behind. If the larger ring is deeper than the shoulder on the smaller ring then make the tapered part wider than this so you can get hold of it to withdraw it.

Jo

Hi Ed, The three springs sit in three holes in the inner ring the three balls sit on top of these springs and push down on the springs and into the holes, they will go into the holes compressing the springs until they are flush with the inner ring circumferance the outer ring will then fit on the inner ring over the balls. When the outer ring is fully on the inner ring the springs push the balls up into a groove in the outer ring the outer ring will then turn on the inner ring thus you can set the outer ring to the zero mark and the tension from the balls and springs stop the outer ring from moving when you do not want it to. It is not possible to hold all three balls in place with fingers the tension is too great, this is a difficult one.

Got it the springs/balls fit to the inner not the outer .

Bit of shim wrapped round the inner keeping the balls in place as you slid the outer on

Jo

Edited By Jo on 08/05/2014 10:14:03

Tried this Jo not been a sucess, these springs are quite strong, I think I need to make some sort of split sleeve/clamp.

Have you tried using a Jubilee clip ( worm drive hose clip )? I' ve sorted a few similar jobs with one.

Hi Gorden, I have thought about this and I think this may work but I would need a very narroe clip and at the moment I do not know where to get one from..

The clip would need to be about 6 mm wide, I am going to Harrogate on Saturday maybe find one there.

The clip would need to be about 6 mm wide, I am going to Harrogate on Saturday maybe find one there.

If you can't find one long enough (i never can) you can screw a couple together - as long as they are all the same size and make - and make one long enough that way. The narrow Stainless steel ones would work. Any Motorfactors will have a selection to choose from.

graham.

How about this then.?

3 flat shims thick enough to go from the shoulder on the inner to the middle of the ball bearing. Use a large 3 jaw chuck face up on the bench with the inner in the centre and the three shims radially from the jaws (probably the outside jaws are best) and line up with the ball and spring holes. Fit the springs and balls loose and place the outer on top. With some pressure on the outer to hold everything in place close the jaws and compress the springs and the balls into the holes. With constant pressure the outer should move down to the middle of the balls. Release the jaws and slide the shims out and the outer should click into place.

This is a thought experiment, I have never done it but it should work.

regards Martin

Bit of tin can just a bit wider than the balls to go round and have the end bent up at 90 degrees.

Insert springs with dab of grease or even super glue the lower coil into place, balls on the spring then wrap the band round and grip with a pair of snipe nosed pliers.

Offer the outer ring over pushing the band down to the bottom and then when you are sure some of the balls are inside the ring, remove tension from the pliers and unwrap the band.

Basically you have invented the piston ring clamp again, secret is getting it thin enough to hld the balls but slide down as the outer ring is going on.