Colchester Bantam 127 change gear

[Dan ShillingParticipant @danshilling]

I was wondering if the Colchester Bantam seventies model 127 change gear has a spline?

The reason I ask is recently this gear came up without one which would make it easier to make or have made. See picture.

Anyway if somebody could confirm that would be great and what is the position of those three holes relative to?

 

Edited By Dan Shilling on 17/02/2023 11:00:51

[Dan ShillingParticipant @danshilling]

127 change gear got a spline too?

[Peter Simpson 3Participant @petersimpson3]

My 1964 bantam 1600 has splines. The three holes take roll pins that line up with three holes in the adjoining large gear wheel.

[Martin ConnellyParticipant @martinconnelly55370]

Often lathes supplied with a 127 tooth gear are partnered with a 120 tooth gear and have simple pins to transmit the drive. I would expect that if this is the case the 120 tooth gear would have splines and the 127 tooth gear to be clearance. Having both gears splined may be more costly than the pin drive option.

Martin C

[EmgeeParticipant @emgee]

As Martin says the 127 gear is paired with a 120 tooth and can confirm on my 1966 Bantam the 2 are as-one with the 3 pins.

Emgee

[Dan ShillingParticipant @danshilling]

Thanks all,

seems could work either way maybe that gear in the picture is some after market clone like RDG offer.

The RGD clones I've got are very good though not available in 127 unfortunately.

[Howard LewisParticipant @howardlewis46836]

A 120/127 compund gear makes producing Metric threads on an Imperail machine (or vice cersa ) SO much easier

If you know the DP and pressure angle, it may be possible to modify a gear from another lathe so that it can be pinned to the exsisting 120T gear. And then you will be in business!

Howard

[Brian WoodParticipant @brianwood45127]

Hello Dan,

These gearings have a special interest for me and the 120/127 combination gear can be approximated to a combination based on 17/18 instead which is very close in result to the pucca version. Thus 85/90 might be a more readily obtainable pair to build into the gear train

Regards Brian

Edited By Brian Wood on 17/02/2023 15:05:05

[Dan ShillingParticipant @danshilling]

Posted by Brian Wood on 17/02/2023 15:04:37:

the 120/127 combination gear can be approximated to a combination based on 17/18 instead which is very close in result to the pucca version. Thus 85/90 might be a more readily obtainable pair to build into the gear train

Edited By Brian Wood on 17/02/2023 15:05:05

Thanks Brian,

did not think of that and that combination probably more cheaper too.

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