Controllable clock hands

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.
 
My first thought would be RC servos, but you mentioned that sometimes the clock would keep normal time. That means you'd need something like an arduino that knows what time it is and can have cues loaded for your countdown.
 
Hello and Welcome...

First question... what's your budget, how much time do you have and how much time do you want to invest in it?

Yes you could do a variable speed motor, maybe a relay with time based triggers.... there are a lot of remote control master clock options out there in the market.

I think your bigger issue is going to be the 14' caveat... that's going to be quite the torque to put on a motor to do what you want.....

What do you have to build it out of and how fast does it need to move? There may be a manual solution that could work better in this case...
 
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.
Two queries:
1; Is the face of the clock vertical; on the wall of a set for example rather than flat on the floor?
2; Can I assume you're on a budget??

If the former; consider building it with two shafts, one inside the other, and two hands on the rear of the wall.
When you're fabricating the hands, make them long enough to extend past their shafts and include counter-weights so the hands will remain stationary wherever you stop them.
Put corresponding numbers, hands (and additional counter-weights if required) on the rear side then operate it manually. Have a real clock on the back of the wall, preferably with a sweep second hand, so the person (or personS) operating your clock have a reference handy to get the correct rhythm / cadence.
You might also consider fabricating the back hands as two circular cuts of plywood, large enough for one operator to stand either side of the pivots; if you go with two flat circles of plywood, you could mark hands on the plywood.
Toodleoo!
Ron Hebbard
 
At 14' , that is a challenge. At 14", we can talk RC servos and perhaps a Phidget interface to control. At 14', we're talking about maybe a 6' minute hand? Ron's approach is certainly viable. Another concern I would have is keeping the hands stable and flat enough that the hour hand doesn't catch on the minute hand as it comes around it. Let's put it this way, the Equity theater in town here used projections for their production of A Christmas Tale when last they did it.
 
Thanks for the responses everyone! I do have a couple grand to throw at this issue (budget for two productions is $40K so I'm trying to stay under $5K for the clock if possible-- it's the one big thing I'd like for this show).

It does look like manual would be a good option here. The clock will be vertical. I plan to build it as a theatre flat out of 1/4" luan. Anyone have thoughts on focusing a projection onto the clock face rather than projecting the clock entirely?
 
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.
Google: "Apollo clock gobo rotator"
Toodleoo!
Ron Hebbard
 
It is possible to make but a physical clock with motorized 7ft hands will likely be dangerously powerful if you want it to advance more than a couple times faster than normal with the hands in the correct sync. I don't know what you are defining as "very fast" but if my math is correct the tip speed of the minute hand advancing at 4 seconds per "hour" would be around 660 feet per minute.
 
Thanks for the responses everyone! I do have a couple grand to throw at this issue (budget for two productions is $40K so I'm trying to stay under $5K for the clock if possible-- it's the one big thing I'd like for this show).

It does look like manual would be a good option here. The clock will be vertical. I plan to build it as a theatre flat out of 1/4" luan. Anyone have thoughts on focusing a projection onto the clock face rather than projecting the clock entirely?

Focusing would be determined by your hanging positions. Seeing as it’s a center piece it sounds like you will also have ambient lighting as well. Shooting from the hip a stack of 10ks at a 20-30’ distance. But again that all is determined by what you have to hang it from.
 
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.
Two more queries:
a; 14 inches or 14 feet?
b; Line voltage powered clocks typically have shaded pole synchronous motors.
You could try connecting a sweepable sine wave, audio oscillator to the line level input of a butch audio amplifier with a 70 volt, or higher, output then using the variable frequency output of the amplifier to power the clock. The small synchronous motors commonly used in 120 volt powered clocks ought to be within the output rating of any medium powered 70.7 volt amplifier.
Toodleoo!
Ron Hebbard
 
It is possible to make but a physical clock with motorized 7ft hands will likely be dangerously powerful if you want it to advance more than a couple times faster than normal with the hands in the correct sync. I don't know what you are defining as "very fast" but if my math is correct the tip speed of the minute hand advancing at 4 seconds per "hour" would be around 660 feet per minute.
And they told me I'd never use all that math...
 
Biggest issue here is the size of the hands. Even if made from Aluminum <long piece put a slight bend in it longitudinally to give it rigidity.>, and you could build in safety factors for the speed as @Dover mentions above the torque require to turn that motor consistently will be immense. for safety and power concerns we're talking good size motor, and gear reducer to up the torque. then things get complicated do you run the whole thing off one motor and tap two different reducers or do you actually build a workable clockworks. I think perhaps having just the hour hand be able to spin fast might be an easier way to go. especially if you are talking about advancing several hours in one cue, having the minute had spin that fast would likely cause the unit to take flight and do a spin around the auditorium like one of Kyle's drones.

Also I want to make sure you understand I'm not poo-pooing the idea. I think it's ambitious. I had to tackle a similar problem in a couple different shows. I think the last was Nutcracker. It's a PITA. I'd love to see what you come up with!
 
Anyone have thoughts on focusing a projection onto the clock face rather than projecting the clock entirely?
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Everyone's already been talking about this but here's a visual.

- Nick
 
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Everyone's already been talking about this but here's a visual.

- Nick


I was talking about projections from a projector but this is a great cheap idea I didn’t think of. A gobo rotator in a 750 on the first electric would totally work and be super cheap. Granted you would have to set the rotator to always be tocking/ticking but would be a great solution.
 
Given that kind of funding and assuming I could find someone with microcontroller programming skills, I’d go with stepper motors driving coaxial shafts carried in 2 pillow block bearings each, mounted on an A frame whose height is centered on the dial.

Since the hour hand is shorter and has less momentum, I’d drive it with the smaller inner shaft. The reasoning is that the attachment between the smaller shaft and the hand will end up smaller and I can see it flexing if it’s driving the longer minute hand. A tube has less bending moment than a solid does.

You could use sprockets as the interface between shaft and hand. The hands could a light aluminum frame with a luan face or painted fabric like a flat.

edit, after setting my phone down in satisfaction of a job well done, I find I can’t picture in my head how the outer shaft would run past the inner shaft bearing on the dial end. Sigh…. We have several machines here with coaxial shafting but I don’t think they would work for this.

Michael
 
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Given that kind of funding and assuming I could find someone with microcontroller programming skills, I’d go with stepper motors driving coaxial shafts carried in 2 pillow block bearings each, mounted on an A frame whose height is centered on the dial.

Since the hour hand is shorter and has less momentum, I’d drive it with the smaller inner shaft. The reasoning is that the attachment between the smaller shaft and the hand will end up smaller and I can see it flexing if it’s driving the longer minute hand. A tube has less bending moment than a solid does.

You could use sprockets as the interface between shaft and hand. The hands could a light aluminum frame with a luan face or painted fabric like a flat.

edit, after setting my phone down in satisfaction of a job well done, I find I can’t picture in my head how the outer shaft would run past the inner shaft bearing on the dial end. Sigh…. We have several machines here with coaxial shafting but I don’t think they would work for this.

Michael
It's almost like we're trying to reinvent the clock? ;)
 
Hehe, maybe. I wondered if anyone would pick that up. This is how clocks and watches have been built for hundreds of years. What I described is called the motion train. The steppers would be the going train in effect.

I did figure out the bearings. You’ll need press fit bearings like the ER style or oilite bushings pressed into the tube for the shaft to ride in. Set screw bearings like the ER’s are nice since they will take care of axial location without extra parts. I’d gotten wrapped up with how the cartoners at work operate. They have space for outboard bearings on each end of the shaft. Clocks don’t.

Wikipedia on clock trains
Michael
 
Hehe, maybe. I wondered if anyone would pick that up. This is how clocks and watches have been built for hundreds of years. What I described is called the motion train. The steppers would be the going train in effect.

I did figure out the bearings. You’ll need press fit bearings like the ER style or oilite bushings pressed into the tube for the shaft to ride in. Set screw bearings like the ER’s are nice since they will take care of axial location without extra parts. I’d gotten wrapped up with how the cartoners at work operate. They have space for outboard bearings on each end of the shaft. Clocks don’t.

Wikipedia on clock trains
Michael
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.
 
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.
A query and 2 thoughts:
Did we ever get an answer to: 14 inches OR 14 feet ?
Regardless of the size; consider a black faced clock fabricated with Rosco's Black rear projection screen, plus their dual gobo rotator and clock gobo's.
The dual gobo rotator will be a bit spendy but it could find uses in future productions and be written off over 10 years.

If your production doesn't use your main curtain, you could open the house with the set bathed in a suitable pre-set and the clock displaying real time; you could end the first act with the clock still exposed and again displaying real time 'til the end of intermission.

Assuming you have a main curtain, you could either close it after final bows or leave the curtain open, end with a post-set and the clock again displaying real time. @midgemusic11 are you still with us / playing along at home?
Toodleoo!
Ron Hebbard
 
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