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Tightening the saddle on Colchester Mk 2

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graduate_owner

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Hi all,
I have a Colchester Mk2 square head with gap bed, nice lathe, but the saddle has slop. Can anyone tell me where the gib stripe tightening screws are, and any hints on solving the issue?

Many thanks

K
 

Trevanion

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What Model is it? Mascot, Student, Master, Bantam, Triumph?

Describe what you mean by "Slop", pretty much all lathes have some degree of backlash, having no backlash is not good. My handwheels move about 1/8th of a turn before anything moves when changing direction.

I have a CVA lathe and the saddle is tightened to the bed by 4 ball bearing races on each corner of the saddle which are on camshafts to either tighten or loosen the fit. Not sure if that's how the Colchester's saddle is attached.
 

graduate_owner

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Sorry, my mistake, it's a Colchester master mk 2 square head. When cutting anything more than very light cuts I can feel the whole saddle move. Also when screwcutting I always get multi start threads however I try, and I think it is because there is enough movement to cause mis- alignment of thread start point.

I am hoping that it is the gib strips that is the problem.

Deema - is that for the master mk 2 gap bed?

K
 

novocaine

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the screw cutting sounds more like worn half nuts rather then movement on the ways.
 

flh801978

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K
to start with do you mean the whole saddle moving left to right or up and down? or the cross slide/compund slide?
with the lathe off try engageing the half nut fully can you move the saddle left to right at all with the hand wheel?

how are you cutting threads? imperial or metric?
is yours an imperial or metric lathe?

Ian
 

Keith 66

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On the Colchester square head lathes the gib strip is on the rear & underside of the saddle, cant remember if its a square strip held on with bolts or a dovetail strip like the cross slide! there will probably be approx 6 of them, Cross slide & compound slide have a dovetail gib with small allen screw adjusters with hex head lock nuts.
If the lathe has heavy wear you may find it gets looser towards the chuck end.
 

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