Old Hole Plate Questions

[Chuck TaperParticipant @chucktaper]

[Chuck TaperParticipant @chucktaper]

Into my possession came this.

180, 144,84, 50 holes. & Appears old (see font used in stamping)

It's approx 1/4inch thick – 7inch diameter – bronze.

Any thoughts on the specifics of what this is or what/how it was used.

Could it be specific to clockmaking??

Thanks in advance.

Regards.

Frank C.

[Anonymous]

Probably used for direct indexing for gear cutting and similar. The disc looks like clockmaking rather than industrial. I don't know if the nuimbers are common tooth counts for clocks.

Andrew

[Chuck TaperParticipant @chucktaper]

The three outer rings of holes appear indexed into 12 segments.

The 50 holes ring is indexed into 5 segments.

Regards.

Frank C.

[DC31kParticipant @dc31k]

The factors of the hole circles correlate with some time-related things.

180 = 2x2x3x3x5 so it contains 60 (seconds in a minute, minutes in an hour)

144 = 2x2x2x2x3x3 so it contains 24 (hours in a day)

84 = 2x2x3x7 so it contains 7 (days in a week)

What puzzles me is that there is no obvious time-related thing that relates to 50 (2x5x5).

The sub-divisions they have stamped on the circles probably has some significance. For instance, why is the 84 stamped every 7 when it could equally be stamped every 6?

[Anonymous]

Posted by DC31k on 04/05/2023 18:00:12:

…why is the 84 stamped every 7 when it could equally be stamped every 6?

Seven is a prime number so can't be factorised?

Andrew

[BazyleParticipant @bazyle]

10 and occasionally 20 is used for (clock) pinions. Just look for 'wheel cutting engine' and you will see something familiar. Often they only needed a few rows of holes so were not trying to get lots of rows of primes like a dividing head plate, but used a large plate for accessibilty and mechanical advantage.

[Author]

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