Colchester Change Gears

Hi All,
I've been asked if I can make 3 gears (2 30T & a 60T) for a Colchester
Lathe (no model yet specified) but since I don't have a Colchester I
have no way (other than by reference to this group) to determine the
specific chacteristics.
I'm hoping that Colchester use the same DP (or Mod), PA and bore for all
their models - just as Myford use 20, 14½ & 5/8" (with 1/8th keyway) -
but look to the collected wisdom for confirmation.
Currently I have photographs of the damaged gears which include a
plastic ruler to provide some scalar reference but even if I could use
them to get a good idea of the DP (Mod) there is no way i could
determine the PA.
TIA.
JG
Reply to
JG
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16 DP, 14-1/2 PA -- Regards,
John Stevenson Nottingham, England.
Visit the new Model Engineering adverts page at:-
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Reply to
John Stevenson
Colchester
eyway) -
The later Student 1800 / Master 2500 series use MOD gears of iirc 1.5 mod whereas the earlier Student & Master of the 'round head and flat head' variety use DP. The hub splines are different as well.
When I needed change gears for my Master 2500 I bought them from HPC and broached the splines.
AWEM
Reply to
Andrew Mawson
As Colchester have made lathes since Queen Victoria reigned, you might need to narrow down the date and model, with such a long run they are likely to have changed their gears at some point. In particular they made lathes with belt drive and screwcutting gearbox for a long time, even after they had introduced the gearbox models (1950s?). The Bantam is particularly confusing as it was a model in the 1920s and 1930s, and then the name was resurrected in the 1960s to described a very different lathe. Bantam gears are available from several sources, but I assume they refer to the internally splined gears for the gearbox type (certainly the ones from RDG on eBay have the splines).
I expect you are after making change wheels for one of the belt models. It would be very unusual if older Colchester's hadn't used the 14.5 degree PA used by every other British lathe for gears - but I can't help with DP or other dimensions.
Steve (Cheshire)
Reply to
Cheshire Steve
from Cheshire Steve
Thanks Steve, (and JS and AWEM for the input) very useful history.
I've gone back to the Colchester owner an dasked specific questions.
The lathe is a Master from about 1950ish. The gears in question are in fact 30 tooth with 3/4" plain bore and an OD of 2.28" - I make that 14DP - and a 40 tooth with 0.8" splined bore, OD 3" which I again make 14DP. Without a detailed study of the tooth form I'm assuing that the PA is 14½°.
RDG don't list either on their eBay site and I gave up trying to phone them today. I suppose that HPC would make them as specials but I would have to be sitting down before I looked at their quote.
The plain bore 30 tooth I don't have too much of a problem with (I'm sure I can borrow a 14DP 14½° PA Hob) but I don't think I could cut the spline using the keyway broach I have :)
I've suggested that the owner call RDG and HPS next week so I'll see what he reports back.
JG
Reply to
JG
I think you'll find the RDG stuff is all internally splined.
You could try calling G&M Tools. They are listing some Bantam gears including 60T - they might be plain bore ones. Worth a call.
Boston gear do 14.5 PA gears. I am not sure if they do 14DP. They are US-based but have UK agents. The exchange rate is rather good at the moment.
But at least you don't have to internally spline any you make, which saves hassle if you are keen to make them.
Steve
Reply to
Cheshire Steve
Colchester
Colchester I
1930s,
gearbox
G&M Tools sometimes have Colchester gears:
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As do Toolco:
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I've bought Colchester gears from both over the years, but it just depends what they have at the time - worth a phone call.
AWEM
Reply to
Andrew Mawson

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