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By DiscoStu
#1170014
Question for you guys - a bit different to the usual questions.

I am looking to make a steam punk themed calendar for a stage show of around the world in 80 days. The calendar will display certain days at different points (different scenes) in the show. The arms need to come to rest so that they sit behind a window displaying "Day"

I have a basic sketch for what the calendar should look like and I can make all the elements but I'm struggling to work out a way of moving it from one date to the next from a switch. Basically I need to have a button that moves the calendar onto the next day.

Image

Any ideas how I can move the calendar on from one day to the next.




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By Dee J
#1170018
Any drive system will need some sort of motive power a feedback system and a control system. The simplest system is motive power by hand, and feedback by eye, brain provides control... ie turn it 'til its in the right place.
Other motive power... probably electric
Feedback... cam and contacts, opto sensor, magnet and reed switch.
Control... relays, analogue electronics or some kind of programmable digital stuff (Raspberry Pi).
If you can possibly arrange for direct turning by hand that will be simplest to construct and most reliable.
By John Brown
#1170023
Small geared motor. reed switch in "window", small magnet on each day. Normally closed contacts of reed switch in parallel with push button to control power to motor. Press button for long enough until the magnet moves sufficiently to let the redd switch NC contacts close, then release button. Thing should turn umtil the next day(with magnet) reaches window. Just like self parking windscreen wipers.
User avatar
By nev
#1170033
How many days?
Could it just be done with a weight and simple toothed steps?
a simple actuator to release a peg, drops to next number. repeat.
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By nev
#1170036
ratchet and pawl were the words I was looking for.

Exquisite drawing attached :)

IMG_1144 (1).jpg
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By MrTeroo
#1170043
Dee J wrote:Any drive system will need some sort of motive power a feedback system and a control system.

The simplest system is motive power by hand, and feedback by eye, brain provides control... ie turn it 'til its in the right place.

If you can possibly arrange for direct turning by hand that will be simplest to construct and most reliable.



+1 for human controlled. Don't over complicate it.
By NazNomad
#1170071
A geneva drive would work perfectly for that. Your 'dates' just need to be spaced equidistant around the axle.

Hand crank it too, even ''remotely'' with a long belt & pulley affair.
By DiscoStu
#1170080
Alas I can't human power this as it's going to be 20ft up in the air above a stage. Nev is like your idea. I'd thought of a solenoid driving a bolt into holes for each day but I could use that to drive the arm of your "pawl" assuming that's the arm bit.


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By nev
#1170113
and a long piece of string in case the solenoid fails :)
I imagine it would be fairly straightforward to knock up a test piece from ply and some nuts and bolts. May need to gear the weight drop or introduce some friction to give a smooth 'turn', but I reckon it would work.
By AES
#1173535
Wouldn't a long flexible drive allow you to hand crank it as required?

20 feet sounds a bit long, but a length of motorbike brake cable (if such things still exist?) should be strong enough I guess - even if it had to be joined, but there again, surely, if they still exist at all, both inners and outers must be originally made in long coils, enabling a single length, no joins? The only real problems I could see with the idea is ensuring the outer is clamped securely enough so that the inner only turns when you wind the handle, plus making the outer "invisible" (same colour/s as the background scenery)?

I agree with the others about "KIS" and all that, and IMO anyway, the best idea is simply to use your own hand/s, eyes, and brain to eliminate all sensors, drive motors and any and all other complications.

HTH

AES
By AES
#1173547
I was having a sleepless night last night, but thinking about it now that I'm awake (more or less!), I think the flexi drive idea is NOT so "brilliant" - on the contrary! :oops:

It would also need some sort of ratchet & pawl to index it into the correct steps. A bit complex.

I now think the falling weight idea is much better.

Sorry for the red herring :oops:

AES
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By MikeK
#1173552
Rather than one spoked wheel for all 80 days, why not two spoked wheels, each with the digits 0 through 9? The digits can come together in the middle for your display, starting at 01 (or 00) and ending at 80. I don't have any suggestions for the advancing mechanism, but I think a combination of electronic for the timing signal and electro-mechanical for the movement should be possible.

A pair of 10-spoke ship's wheels would give a nice touch.
User avatar
By Eric The Viking
#1173596
Obvious question Stu, how big will this thing be?
By Angusdog
#1177974
Arduino, stepper motor(s) and possibly contact switches. The parts would be 30 pounds-ish depending on where you get them from (cough * AliExpress * cough).

Learning to program the Arduino and build a proof of concept would take a beginner a day. Handling the 'numbers on two arms' would only take a little more thought and programming. T'internet is awash with Arduino tutorials so the programming would probably be a cut 'n' paste job.

Versatile and robust (much more so than designing an entire contraption from scratch).

When you get more into Arduino programming, you could add a real time clock, bluetooth etc to change the date without scrambling 20' up :)