Lori’s Clock: Part 2

Checklist:

  • One clock case
  • One clock movement (85 years old, missing pieces)
  • Two 12V DC 60 RPM motors
  • Two circuits for adjusting motor speed
  • 8 or 9 types of battery packs, each rated around 12V with various current ratings

And now we’re ready to get started!

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It’s been a while since I first mentioned it here, so here’s where we stand: Lori is my co-worker at The Able Baker. She makes the scones – I sell the scones. She is the owner of a really cool Sessions clock from 1932 from when the company first began making electric clocks. This clock was made for plugging into an outlet. The cord was frayed, the two AC motors were leaking various fluids, and the clock hadn’t been serviced in decades.

The plan: Cut the cord! Toss the motors! Put in a battery pack to run 2 new motors! Attach the 2 motors to the 2 gears somehow!

This is definitely the most ambitious clock project I’ve taken on, and also the most unusual. I’m basically taking a mechanical/electrical hybrid of a clock and turning into a different type of weird electromechanical hybrid. My idea was, why would a clock need 120V? 12V should be more than enough, and you can find 12V battery packs with an Amp or two if you want.

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The first battery packs I tried, from Radio Shack, wouldn’t run the motor. Unfortunately they weren’t labeled with current ratings so I could only guesstimate based on size what the amperage was. I decided that I was going to go all-in with this project, so I reached out to two of my favorite online superstores – Amazon and McMaster Carr. From Amazon I purchased “12V Tenergy 2000mAh NiMH Battery Pack with Bare Leads for RC Airplanes” for $23.92 and from McMaster Carr I purchased “Disposable Lantern Battery Carbon Zinc, Manufacturer Equivalent Number 926” for $13.74.

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For those who don’t play with household batteries often, almost all batteries are rated at 1.5 Volts with various current ratings. A23 batteries are 12 Volts, so I ordered some A23s, but they took a while in arriving and the two stronger batteries (shown above) actually arrived the same day. I also ordered a battery pack for AAs that would put them in series to be 12 Volts, but that also arrived at the same time as the stronger batteries.

After failed attempts at using Radio Shack batteries and being unable to run the motor at all, I was gleeful when both my Lantern battery and my RC airplanes battery pack ran the motor at full speed. The next step was to hook either battery up to the motor control knob and see if I could adjust the speed of the motor. After all, the speed of the two motors is going to dictate the speed of the clock’s hands.

Mwahaha! Cue the maniacal laughter as I turned the knob up and down and up and down and watched as the motor shaft rotational speed adjusted accordingly.

Pros: It works!

Cons: It can’t be controlled finely, and it rotates too slowly.

I don’t know what I was thinking ordering motors that were 60 rpm. I need much more than 1 rotation per second. RadioShack sells “high speed” motors but what that speed is, is anyone’s guess. Of course, if I can control the speed then as long as I can lower it to the appropriate RPM all should be fine…

What’s left? Attached the gears to the motor shafts (of whatever motors I end up using). This is the super fun part!

I recently joined the Staten Island Makerspace and next week I’ll be getting my wings to fly solo. That means full use of the metal and wood shops, work areas, a cubby to keep some tools in, and 6 days a week access to build and destroy to my heart’s content. I’m over the moon about it, and can’t wait to get to work. First up? Shaving down the shafts of whatever motors I decide to use, so that the gears I have fit over them. I maaaaay decide to make new gears but that would take a long time (weeks, probably) so I’m not sure yet. There’s also a laser cutter… maybe if I could get my hands on some Delrin (polyoxymethylene) I could laser cut new gears and try those out… The possibilities are endless. Whatever I do, I’ll probably start by 3D modeling the gears so I have a record of them for my own use. I have Autodesk Fusion 360 (free for hobbyists and small businesses) and I have a student version of SolidWorks 2015. Either one of those would work perfectly fine. I had some time to kill and dusted off my rusty SolidWorks skills earlier today. As you can see below, I still got it.

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If you don’t hear from me for a while, it’s either because I’ve started living in the makerspace or because I cut off a finger (don’t worry, they’re usually reattachable). A fun side project (a Bruce Springsteen clock!) is also on the docket, but first and foremost is making Lori’s clock run again. Before then, a brief trip to Washington, D.C. to send my disregards to our newest President of the United States.

Cheers,

Margaret

 

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