Hello Russell,

I can't identify it but the gear works out to 24DP for the nearest whole number

Regards Brian

With 60 teeth and something that resembles 360 divisions you could be right.Quite what the missing part or parts are is still a mystery to me. Thinking cap on.

Rick

I have seen one of these, but cannot remember where or what, it' driving me mad, old age. Think the mag drive may be correct, . Bot it does look as if the hole is not on center line, is this just the photo angle? Is the hole tapered ?

Like Gordon W, I have the impression I have seen one of these before, even if not exactly the same I am sure the slot in the boss looks familiar.

One thought thought I have is that the graduations look to be engraved after the part was cast as it would be a lot of hard work to create that profile in the die. Maybe someone modified an existing gear for some purpose we will never know.

Maybe the extended index line at 315 degrees was slip of the engravers hand? although it does just happen to be in line with the cast notch.

Ian P

45 degree as a a timing advance angle is a pretty compelling suggestion.

Neil

Hello Neil,

Yes, I agree but if that was it's sole purpose there are simpler ways of providing the information. My guess is that it had a wider use altogether than that [but what?] and with the gears at 6 degree intervals it would not be a precision piece.

Brian

And another mystery object:-

Obviously a calliper, but one side is engraved in Millimeters/Centimeters the other in "inches", but not quite as each "inch" is 27.38 mm (1.078" ) and each "inch" is subdivided into twelfths. The overall measuring length is 13 Cm. Its rustic and has a lot of age to it (hardly precision). My other clue is that it was found in SW France. No prizes, but I will be interested in your thoughts.

Bob H

Edited By Speedy Builder5 on 05/09/2014 19:00:33

Thanks for that Neil – why is is nothing ever easy? Or simple?

Pah! It's a typical French compromise made at roughly the half-way point between the long and short pouces!

Neil

P.S. I didn't know all this before, just had the memory that the French used to have a 'funny inch' of their own before they went metric.

Neil

If I was making a casting pattern from a finished object that vernier could be quite handy, adding as it does about 8% to the actual dimension.

Eug

Bob,

Maybe a silly question … have you checked the actual size of the "millimetres"

The reason for asking is that 27.38mm [i.e. your "inch"] converts nicely to 1 5/64"

… It might be a pattern-maker's calliper, corrected for shrinkage.

MichaelG.

.

Edit: Sorry, took a telephone call before posting

… Looks like we all got the answer.

Edited By Michael Gilligan on 05/09/2014 20:41:51