General Discussion

Public·35 members

CAD

Hi Steve, Firstly wonderful website and designs, I bought a 3d printer just so I can start printing some of these clocks. I have always loved clocks and mechanical devices and this seems like a really cool way to get into it. I found the video you did on the gear optimization fascinating I am ok in programming and looked at SCAD and BOSL2 for designing gears and might go down that tangent but I wondered what you used for CAD, you mentioned gearotic but I did not catch the CAD program you used. Thanks for sharing your knowledge :) Herbert

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Herbert Kelly

3 days ago

I read lower down that you use Turbocad man did that bring back memories and make me feel old. I have not used turbocad in decades. I am South African so have some memories of being proud that it was developed there haha. I will probably invest time in the new kid on the block then Fusion 360 :P

David Elworthy

29 days ago

How many stages?

I had a general question about clock design. In clocks such as SP5 and SP10, your design goes:

Escape wheel (26 teeth, 10 pinion in SP5) ->

Intermediate Gear A (50/10) ->

Intermediate Gear B (50/12) ->

Minute wheel (54 teeth).

I've seen other designs with only one intermediate gear, for example

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Steve

19 sept

Great question.

The classic design with a 30 tooth escapement and gear sets of 64:8 and 60:8 has a one second pendulum. The 39" pendulum looks great in a grandfather clock but seems out of place in a small wall clock. I wanted the pendulum length to be proportional to the size of the clock.

The only options in a two gear train would be to add extra teeth to the escapement or the 64 and 60 tooth gears. Switching to a three gear train made it much easier to design the entire clock. Now there are three gear sets plus the number of escapement teeth all used to determine the pendulum length. The pinions can have 12 teeth and the main gears would still have less than 60 teeth.

Many of my clocks have a large and medium size variation. The large version often has 1 or 2 fewer escapement teeth to increase the pendulum length slightly. And the horizontal format of SP5 adds more teeth to shorten the pendulum length.

The extra intermediate gear is used for both reasons you mention. I want the pendulum length to be proportional to the clock, and I try to use 12 tooth pinions. Switching from 8 tooth to 12 tooth pinions should more than make up for the increased friction from the additional arbor.

One downside is the escapement rotates counterclockwise and faster than 60 seconds, so the second hand is not available.

Steve