Colchester Change Gears

16 DP, 14-1/2 PA

-- Regards,

John Stevenson Nottingham, England.

Visit the new Model Engineering adverts page at:-

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

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)

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

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

Colchester

Colchester I

1930s,

gearbox

G&M Tools sometimes have Colchester gears:

As do Toolco:

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