Author Topic: A noob attempt.  (Read 3318 times)

Offline jltrent

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A noob attempt.
« on: November 20, 2010, 05:44:48 PM »

During the hot spell a few months back, it was too uncomfortable woodworking in the garage, so spent the time dabbling with a wooden geared clock concept I had been mulling over for some time.  Essentially, am looking to create a side mount wall clock with an 8 day movement, with bubble glass doors on the front and the back.  Found a good source for 14" bubble glass which drove the case size, and arrived at ~16 diametral pitch gears in order to fit the works in the case.  Am able to get the escape wheel spinning somewhat consistently with 4 coke cans as test weights (~3.5+ lbs), with a drop of ~72" for 8-days worth of revolutions.  This using triangular shaped teeth.  Based on some friendly advice from another clock builder and the resources on this forum, am making use of racer bearings for the bushings, and K&B brass tubing for the arbors.  The wood is baltic birch from Michael's Craft stores.  Using the software utility I posted in the Tools section of this forum, I am making use of the CarveWright to cut the wheels, pinions, the grasshopper escapement, circular case, and the interior bushing mounts that attach to the case.

(See attached images.)

Once the summer hot spell let up, I wasn't able to dedicate as much time to working through the next step of tying in the pendulum, which will hang on the front side.  Prior to even arriving at the 15" case size, I initially did some tests of a circular compound pendulum of about 12" in diameter, and believed at the time that I could get a 2 sec period out of the configuration.  This didn't appear to be the case in practice, though, when I actually tried to shape and hang the pendulum.  Regardless of how much counter weight I added to the top of the pendulum, I could never get the period greater than 1.5 sec.  And I tried a grasshopper of 60 teeth to accommodate a 1 sec period, but the tolerances and tooth spacing were too tight for my liking.  And I still haven't a clue as to how much weight will eventually be required to drive the pendulum.  Also, I'm somewhat concerned that the grasshopper might not be as forgiving as the deadbeat when in comes to irregularities in the driving force to the escape wheel, and subsequently, might end up with a clock that keeps irregular time.  In any event, I'm now dabbling here and there, when time permits, with the idea of having a longer compound pendulum that passes through the bottom of the case by about 10" or so, making it easier to establish a 2 sec period...

Once the cold spell hits in Jan / Feb, I'll jump back into it in earnest...

Jon

Offline chuckknight

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Re: A noob attempt.
« Reply #1 on: November 25, 2010, 10:09:40 PM »
THAT is your first attempt?!  I'm sincerely impressed.

Please PM me...for some reason your account won't allow me to PM you.

Offline jltrent

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Re: A noob attempt.
« Reply #2 on: December 01, 2010, 04:35:59 PM »

It's still not a clock yet!  And it's actually my second attempt.

I created a standard "straight stack" (see attached) about 2 years ago, but never completed it, as the design would only permit a run length of less than a day.  (At the time, I was trying to work through the kinks of creating gears from my CNC.)  I wasn't interested in completing a clock that I had to wind every day, so hence my current design.  My attempt to finish it in Jan / Feb will be perfect, because if I can't make it work, it will at least be able to help heat my home.