Rack Pinion for Colchester 13" Mk.2 Master

Domodude17

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The carriage handwheel on my Colchester 13" Mk.2 feels a little sloppy. I have heard that the pinion can be a wear point as it's deliberately made softer than the rack. I'm going to disassemble the apron to clean it out and service any issues I come across, so i'm wondering if anyone knows the size of the pinion I need. Catalog calls it out as PN 7807, and it is described as "Rack Pinion, 12T". I could likely just turn the worn pinion off and make a new one to loctite on the shaft from pinion stock from mcmaster carr, just don't know the size of pinion I need. Pitch, etc.
 
Loctite would likely not be strong enough for that application.
 
On my Colchester, the pinion shaft is available from the 600 Group. The last time I checked it was over $650 plus shipping from England.
I just lock the carriage when needed.
The rack would be cheaper than the pinion, I think.
You can order racks in all different gear sizes and lengths. Easier to replace, I would imagine.
I've never heard the pinion gears are soft. Is this common?
 
I mean, I can always press fit it on and cross drill it, add a keyway, etc.
I suppose, if it has a thick enough cross section. A shrink fit has 3 - 5 times the holding power of a press fit. Having some slop in the rack/pinion does not really hurt function in any way that I have ever experienced, and I have run many worn out machines.
 
I did a shrink fit + pin repair job on the pinion for my Bolton when I messed it up. Details are here:


John
 
I've never heard the pinion gears are soft. Is this common?
It is common in some situations for a smaller gear to be harder than a larger gear since the teeth on the smaller gear will see more engagements/wear than the teeth on the larger gear. If there is any difference on this lathe (which would surprise me), I would expect the pinion to be harder.
 
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