Tmasters
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« on: January 01, 2019, 10:43:59 AM » |
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I'd love to make a fancy wooden-gears clock with exposed moving parts for show, but one that doesn't need winding and keeps accurate time by being driven by an accurate motor, preferabl y battery. Standard clock movements likely don't have enough torque to drive a gear train. I could use a stepper motor and an Arduino or Raspberry Pi, but that feels like overkill. Ideally I'd like just a self-contained motor internall y geared down to low RPM, but crystal controlle d for stable RPM. Does anyone have an idea? Thanks!
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ArtF
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« Reply #1 on: January 01, 2019, 12:06:04 PM » |
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Hi:
If you build it from wood, and drive it with a motor, to make it accurate youll need a microproc essor of some sort in the end if you wish it to stay accurate. Wood has too much tendancy to shift size and dimension so one would have to have some sort of sync measure in there. (Usually the sync for a wooden clock is its maker when winding.). You can approach accuracy with a cheap arduino that simply pulses a pendulum to keep it swinging while at the same time counting the swings though. Trouble with wooden clocks exposed to show motion is that not much motion occurs other than the pendulum unless you get fancy with moving trains in there to mark events. Second hands are non typical for that reason in a wooden clock. Of course all thats up to how inventive you are, I have seen some very cool wooden clocks, but most dont run long, a day is a good run for most hobby build wood ones. Masters get a few days, but time running before winding is an indicatio n of how good one is. (Im not that good, I rarely get more than a few hours from a good looking one, which is why I build tickers occasiona lly as once I remove the need to tell time the actions can be as varied as I like..
Art
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Tmasters
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Posts: 8
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« Reply #2 on: January 01, 2019, 12:25:42 PM » |
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Art - Thanks! I figured I'd get that answer, but I'm always hopeful. Now I have to work up the ambition to get into a stepper motor with computer control.
Tim
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ArtF
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« Reply #3 on: January 01, 2019, 04:04:09 PM » |
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Tim: All that having been said, a $1.00 ebay arduino uno with a 1$ ebay arduino stepper driver will drive a clock fine, steppers are pretty cheap.. say $5.00 for a small one.  Art
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Ya-Nvr-No
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« Reply #4 on: January 01, 2019, 04:21:10 PM » |
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there ya go... spending my money again.  happy new year all enjoying my AZ winter holiday stay safe stay warm
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Tmasters
Newbie

Posts: 8
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« Reply #5 on: January 01, 2019, 04:33:53 PM » |
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It's not the money. It's just that I'm a lot better with 3D printing and CNC milling than I am with Arduino control. But I guess we're never too old to learn a new skill...
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ArtF
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« Reply #6 on: January 01, 2019, 08:08:05 PM » |
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Hi Tim: I think youll find controlli ng a stepper with an arduino isnt all that hard. If you get confused as to how Im happy to help when people have questions even on an arduino control type questions . Ive controlle d a few steppers in my time. Making a small arduino control a stepper has lots of examples and open source on line. I made a marble/sand drawing video awhile back and I still have code for making them move aorund here somewhere .  YaNvrNo: >>happy new year all >>enjoying my AZ winter holiday Now thats just rubbing it in as I just finished parking the snowblowe r and spreading salt.  , Happy 2019.. Art
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John T
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« Reply #7 on: January 02, 2019, 09:58:00 AM » |
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Most clocks that I design and build run at least 30 hours by design and half a dozen or more run a week on a winding. Having said that they are as good barometer s as they are time pieces - a change in the weather will upset them and often cause them to stop. If I want to know exactly what time it is I look at my wrist.
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1% inspirati on 99% try, try again
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ArtF
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« Reply #8 on: January 02, 2019, 10:14:27 AM » |
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John:
And thats a tribute to your workmansh ip, getting a week on a wooden clock identifie s you as a craftsman in my opinion.
Art
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ArtF
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« Reply #10 on: January 02, 2019, 02:31:44 PM » |
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True, Sync motors are the gold standard and a lot less hassle. Art
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Tmasters
Newbie

Posts: 8
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« Reply #11 on: January 02, 2019, 04:20:38 PM » |
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Steve - Wow, that looks like exactly what I want! Constant RPM but no computer to deal with. I'll look into that and check to see if it has any interesti ng relatives . Thank you!
Tim
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steve323
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« Reply #12 on: January 23, 2019, 04:28:06 PM » |
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Tim, Your query sparked my interest, so I ordered a couple of motors similar to these https://www.amazon.com/dp/B07G345S4H Similar items are common on Ebay for around $3 each. They appear to be very popular for running the turntable s in microwave ovens. The first test runs amazingly quiet with a lot of torque because of the gearing. I may try to run one for a few weeks with a load to see if it stays quiet. One huge disadvant age is labeled clearly in the image as CCW/CW. The motor does not have a start capacitor to define the direction and will randomly start either clockwise or counter-clockwise. Direction al synchrono us motors are a lot harder to find. It should be a fun challenge to use a couple of one-way clutches and gears to force the output to run in one direction . Steve
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John T
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« Reply #13 on: January 24, 2019, 06:25:34 AM » |
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Just a thought, If I truly wanted to have exposed wooden gears and an accurate time piece - I would look at running th clock backwards - by that I mean I wouldn't start at the great wheel but rather start at the seconds hand and let everythin g else follow it. In a normal geared clock you start with a lot of power (weight) and through gearing slowly have less and less actual power at the gear tips. If you apply very small power from an electric movement at the seconds hand you could let there rest of the mechanism just follow along.
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1% inspirati on 99% try, try again
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Tmasters
Newbie

Posts: 8
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« Reply #14 on: January 24, 2019, 06:56:58 AM » |
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I agree, and that was my eventual plan. But I'm still hung up on motors. The many synchrono us motors I looked at would be perfect if it were not for the fact that they all have an average rated life that is much too short for a clock that runs continuou sly. So now I'm looking at a pendulum movement with a hidden magnet in the base of the pendulum and a hidden electroma gnet behind the front panel. I would use a simple microcont roller to apply tiny tweaking pulses to keep the pendulum on track.
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