Mystery clamps bits chucks accessories?

[RodJB]

Anyone know what these are for?
There are 8 pairs of what appear to be matched accessory bits. They’re numbered 0, 20, 30, 40 & 45, 60, 75 & 90
A second pouch contains an identical set.
I am trying to work out what they might be for. They were in a retired watchmakers bench. I don't know if they're something to do with horology or maybe machinist accessories…

 

[Reconnaissanceman]

These items resemble weights for an Atmos suspended balance wheel, but not exactly.

 

[RodJB]

These items resemble weights for an Atmos suspended balance wheel, but not exactly.

Thanks for your reply but I don’t think that’s what they are.

 

[Betzel]

I certainly don't know, but noticed they each have a slightly different rounded edge. I wonder if they're some sort of a radius gauge/template?

What do the edges look like?

 

[RodJB]

I certainly don't know, but noticed they each have a slightly different rounded edge. I wonder if they're some sort of a radius gauge/template?

What do the edges look like?

The curved edges on each are exactly the same shape except of course with a longer run off on the larger ones. The bottoms are flat

 

[Betzel]

So it looks like there is some wear (?) on those curved surfaces, but it still looks pretty rough to me, so not high precision like a gauge block edge, etc. I still can't imagine how they would be used to mark or confirm a radius matching a particular cylindrical edge - or say why they would be needed if cutting a round edge as we do all the time on lathes, unless it was for quick work to check an edge somehow. But, each cut changes the resulting edge of each bar, and its radius so that seems silly. Maybe one of the more general machinists here will drop by, spot them, and clear this up

 

[RodJB]

So it looks like there is some wear (?) on those curved surfaces, but it still looks pretty rough to me, so not high precision like a gauge block edge, etc. I still can't imagine how they would be used to mark or confirm a radius matching a particular cylindrical edge - or say why they would be needed if cutting a round edge as we do all the time on lathes, unless it was for quick work to check an edge somehow. But, each cut changes the resulting edge of each bar, and its radius so that seems silly. Maybe one of the more general machinists here will drop by, spot them, and clear this up

There is no wear on the surfaces, they look unused to me…

 

[gmorse]

Hi RodJB,

Where there are two blocks on the same side, is there any correlation between the spacing between them and the numbers stamped on the side, or the width of the block on the single ones?

Regards,

Graham

 

[karlmansson]

There is no wear on the surfaces, they look unused to me…

I think he was saying that the radiused profiles look like they have rough surfaces. I agree, then look like they were stamped and then plated without any additional finishing in between.

 

[wisty]

No Idea what device they are for, but they look to me like some sort of sine bars for setting angles. If I measure the length of the bottom edge and plot the lengths against the numbers marked on them, then lengths of 0-40 ( the ones with one lug) are the sine of the marked angle (plus a base number corresponding to zero. The lengths of 45-90, two lugs, are the cosine of the marked angle - again allowing for the length of 90 (& zero - both are the same length).
Diagrammatically

Hope this helps.

 

[RodJB]

Hi RodJB,

Where there are two blocks on the same side, is there any correlation between the spacing between them and the numbers stamped on the side, or the width of the block on the single ones?

Regards,

Graham

I don’t see any correlation.

 

[RodJB]

No Idea what device they are for, but they look to me like some sort of sine bars for setting angles. If I measure the length of the bottom edge and plot the lengths against the numbers marked on them, then lengths of 0-40 ( the ones with one lug) are the sine of the marked angle (plus a base number corresponding to zero. The lengths of 45-90, two lugs, are the cosine of the marked angle - again allowing for the length of 90 (& zero - both are the same length).
Diagrammatically
View attachment 747430
Hope this helps.

That’s above my pay grade…

 

[gmorse]

Hi RodJB,

Maybe this Wikipedia article will help. Trigonometry was a long time ago for me!

Many thanks to wisty for cracking this mystery.

Regards,

Graham

 

[RodJB]

Hi RodJB,

Maybe this Wikipedia article will help. Trigonometry was a long time ago for me!

Many thanks to wisty for cracking this mystery.

Regards,

Graham

Have

Hi RodJB,

Maybe this Wikipedia article will help. Trigonometry was a long time ago for me!

Many thanks to wisty for cracking this mystery.

Regards,

Graham

I’m now searching using terms like sine bar gauge block etc but not coming up with anything similar…