Now that Clock #3's escapement seems to be working, I replaced the center pinion with a v-pulley. I made the v-pulley from two 1/8" plywood disks in which the edges were beveled in the lathe. I used hot glue to adhere the disks together, and used a heat gun to ensure the pulley was evenly glued. The v-pulley was secured to the center wheel by a pin. It seemed that this would grip an 80 lb monofilament fishing line if a counterweight was used. The line settles into the groove for an effective radius of 0.75 inches. The clock ran for over an hour on 3.25 lb drive and 0.5 lb counterweight, which works out to just about 2 inch points of torque on the center wheel.
I also noticed previously that escape wheel wheel drifted up on its arbor, so I added a small wooden washer cap that press fit to the arbor. This seemed to work well enough.
Sunday, September 10, 2017
Tuesday, September 5, 2017
Clock 3 torsion pendulum updates
I made several updates to Clock #3 over the weekend... in the end, it is running with about 1.75 inch-pounds of torque on the center wheel.
Paradoxically perhaps, I found that it runs better with the right angle transmission meshing at the top rather than the bottom...
But then I found that the pivot below was unnecessary. This reduced friction somewhat, and lengthening the pivot considerably was helpful.
Initially this seemed to reduce the needed torque to around 1 inch pound. With two pounds on the balance (one pound is shown above), this seemed very stable. The center pivot was set in the wood frame. Unfortunately, but since I had to make several drillings to get the depth correct, the hole walls were weak and eventually split. So I inserted a brass bushing...
This bushing was not depthed correctly, so I had to drill out and shim the hole, so it looks less nice than it does above. With the bushing, the running torque is back to 1.75 inch pounds...
Additionally, I found that occasionally the escape wheel would skip. The reason is the when the wheel rides up on the locking detent (black arrow), it deflects the detent too far and the wheel slips past...
Paradoxically perhaps, I found that it runs better with the right angle transmission meshing at the top rather than the bottom...
But then I found that the pivot below was unnecessary. This reduced friction somewhat, and lengthening the pivot considerably was helpful.
Initially this seemed to reduce the needed torque to around 1 inch pound. With two pounds on the balance (one pound is shown above), this seemed very stable. The center pivot was set in the wood frame. Unfortunately, but since I had to make several drillings to get the depth correct, the hole walls were weak and eventually split. So I inserted a brass bushing...
This bushing was not depthed correctly, so I had to drill out and shim the hole, so it looks less nice than it does above. With the bushing, the running torque is back to 1.75 inch pounds...
Additionally, I found that occasionally the escape wheel would skip. The reason is the when the wheel rides up on the locking detent (black arrow), it deflects the detent too far and the wheel slips past...
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