Monday, December 31, 2018

Clock 4 detent issues

I installed a new(er) 1/3 hp 1725 rpm motor on my lathe since the bearings on the old one were dead.  It runs much better than before!

The detent mechanism for Clock 4 uses a gate invented by Philip Woodward (I think).  The detent sits on a pivot near the pin escape wheel.

The detent is fairly long, but just press fit into the frame.

The detent is cut from a small piece of white oak.

Here is the detent after shaping.

There are many issues with the detent, and it doesn't run at the moment:
  • The gate is very thin.  I broke two detents already
  • Woodward didn't seem to bank his detent, but it looks like I need to since wood has more flexibility than metal
  • The catch for holding the pin is very touchy as to how deep it is.  Woodward suggests that it might work as just a small depression, but this caused the pins to jump out.  Too deep, and they can't clear when the escape wheel recoiled... in which case the pins stick.
  • The pins of the escape wheel are too inaccurate in their placement
  • The pins of the escape wheel are too inaccurate in their vertical alignment
  • The pins of the escape wheel are not all the same diameter (because some of them split in the process of being installed).
  • The relative positioning of the catch and the gate slot is quite delicate, and there isn't much clearance.
  • The counterweight portion of the detent governs how much weight is needed to run the escapement.  This needs to be very light.
A few times, I could feel the escapement "almost working" under my hand, but it wasn't consistent enough to run under a weight.

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