Controllable clock hands

End of the day you are still talking about tons of tons of torque necessary to keep the hands from spinning out of control when going down or stopping when going up.
With an appropriately sized counterweight you'd need a lot less torque.

And if you're really talking a 14' clock, small 3 phase motors, VFDs, and a little PLC to control them would be pretty easy to acquire and program.
 
With an appropriately sized counterweight you'd need a lot less torque.

And if you're really talking a 14' clock, small 3 phase motors, VFDs, and a little PLC to control them would be pretty easy to acquire and program.
I'm thinking a servo (essentially a 3 phase motor) and controller for each hand as I've never had much luck with accurate positioning using VFDs. They might run as high as $1K/set, plus a PLC with motion control or even an EPS32/Arduino/teensey and a bit of interface circuitry should do it. You will probably need a set of regenerative braking resistors to dump the current on deceleration unless you do it fairly slowly. I'd put the counter weights on the tube and shaft, this would allow the hands to be lighter and look cleaner.

One of my concerns is the flight worthiness of the hands. If they have to much of an airfoil shape, bad things will happen. Also, this is a giant spinning wheel of death, it needs guarding or to be off the floor. It doesn't need to spin all that fast to give the illusion of running away but it's still a lot of mass that won't stop on a dime.

And I actually know what tons of torque looks like. It's the size of a freight train locomotive but way slower. I did all the electrical/electronic maintenance on the 150 T-ft (300.000 Lb-ft) manipulator when I worked at Jorgensen Forge in the 90's. It was used at the 5000 ton press to manipulate ingots up to 100 tons which are about 94" tall by 95" in diameter before forging. The jaws looked like parallel jaw Bernard pliers but stood almost 6' high. Sometimes I miss that place just for the shock value. I did find a picture if anyone wants to see it.

Michael
 
Our CC clock 25' diameter controlled with 1 dc motor and Creative corners gear. Setup like a real clock. PM me your email and I can send some details.
 

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Here is our CC clock 25' diameter controlled with a dc motor and Creative corners gear

Google refused to open your linky up here north of little Donnie's Walls.
Toodleoo!
Ron Hebbard
 
So we went the stepper route and ended up opening this show with a clock that didn't have hands.... the most embarrassing moment of my career.... I would recommend staying away from individually controlled hands, steppers/ servos and Arduino if at all possible. We use a DC motor scavenged off some other piece of equipment that we had in stock coupled to an old DC max from Creative Conners. The gearing is CNC cut birch ply and modeled from actual clock gears. It's a brain scratcher to figure out (shaft layout) but it's solid and keeps time accurately. For our hands, I went with alupoly sheet from a local plastics supplier. We've wrecked several hands twisting them up together but it is from the testing and movement of the frame that the clock is rigged to. The hand speed in the video is show speed and is capable of double that in real life, also has backward spinning to go back in time.
 
Good Morning all

First I agree with the projection option

If you want a real clock I would consider DC motors driven by PWM controlers
A number of DMX to PWM drives are on the market at reasonable cost
You will have to be sure the drive can handle the motor you choose



I edited this after I rechecked the spec's on my first choose of drive
:p
 
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Hi everyone,

I am trying to figure out how to build a 14' clock with clock hands that can be controlled on cue. The idea is that sometimes the clock will keep normal time, sometimes the clock hands will go very fast to show time running out, and sometimes they will tick faster than real time but still in sync with one another. Does anyone have any idea how I might do something like this? I know I will need probably two motors (one for each hand) but they need to have variable speeds that are controllable remotely.
@midgemusic11 How did you eventually solve / resolve your 14' clock dilemma? Pictures, front and rear PLEASE. We love pictures,
Toodleoo!
Ron Hebbard
 
@Van @almorton @midgemusic11 Joined July 29th, 2021 and was last seen July 29th, 2021. It was a fun exercise, I wonder if she needed 14" or 14' hands?
Toodleoo!
Ron Hebbard
 

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