So i need a hand crank system for a show with two cranks, but they need to counter eachother. What I mean is, when one person uses a crank, the other shoudl be able to reverse its force with the other.
I cannot solve the system so if you have any ideas, please help.
mutual masturbation?
>>8075813
hah no, they are to be used to slow down or speed up a clock. I mean, one speeds up the clock, but when the other is turned, that one stops or pushes back the clock based on the force applied.
>>8075861
Easiest solution is to run the clock with servo control and have a digital counter for each crank. You'd have two crank sensors attached to a microcomputer and depending on the values that comes from the cranks it either run the clock forward or backward.
>>8075810
frankly, your problem description is very poor, just draw up a diagram with explanation
god, that sounds great but can you please be more specific. I'm not really an engineer.
Or just explain to me as you would explain to someone that would be able to execute it so that I can tell one of my engineer friends to do it : )
>>8075883
HEre is the deal; ı have to create a clock that two people can manipulate with help of two hand cranks.One cranks should accelerate the clock, while the other should decrease its speed. The problem is when two people simultaneously use these cranks, one shoudl be able to overcome it. It is like a tug of war with cranks.
>>8075883
this is the best i can do
>>8075887
How the overcoming part works? Are the cranks supposed to be mechanically connected? Can they be turned separately? Does overcoming happen at random?
As I imagine the simplest way would be to use arduino, you can directly drive clock with arduino. Clocks use one way turning stepper motor. You would need to hook up a potentiometer to a crank. Write some simple code and that's it.
>>8075919
that's the part I'm having difficulty with. They should be able to be turned separately and the overcoming should be based on the speed of lever, meaning the one with more speed should overcome the slower crank.
I was thinking about doing it mechanically, but now that everybody's offering digital solutions, i guess that would be the way to go.
>>8075934
Oh, I thought it was supposed to be something like arm wrestling. Connect some cheap dc motors with gearing to the crank, their output voltage will be directly proportional to the turning speed. Also you'll need to add some friction element to cranks.
>>8075938
alright, that sound plausible. So what you're saying is that I should turn these cranks into generators. How do we make one cranks to slow it down, and the other to speed it up?
>>8075952
The arduino would do the thinking
Both cranks should have the same gear ratio, simple
When going from a small to a big gear, the torque increases by multiplying with radiusBig/radiusSmall,
>>8075957
>>8075955
>>8075938
>>8075919
>>8075866
Guys thanks a bunch, what I gathered from this thread is that I should find someone with enough knowledge with arduino to figure this out. I'm printing this page so that I can have some instructions at hand.
One last thing tho, do any of you have any comments or any insight for the person who's going to build this thing. Like a specific model, a cable, a circuit?
Or will this information be enough for someone who understands how these things work?
>>8075977
Yeah, it's easy, they'll figure out the details
>>8075982
alright, thx again. will be back when the system is fully operational.
>>8075977
You could figure it out yourself with google and some forum posts.
There's some details that's missing like do you want the cranks to be without load(based simply on crank speed) or have a dummy load that gives some resistance to the cranking(resulting in fatique eventually)
Essentially what you need is:
2x mechanical crank setups according to previous specs.
2x angle sensors that can rotate 360 degrees and fits the cranks.
1x continous servo motor
1x arduino.
1x power supply.
google how to read angle sensors.
google how to set servo motor speed.
>>8076044
You could simplify / save money on angle sensor by substituting it with geared dc toy motor. You'll get voltage out, no fuss.
You can save on continuous servo, use a storebought clock, it already has a special case of stepper motor inside, you can drive it directly from arduino, nothing else required.
>>8076054
>you can drive it directly from arduino
There's demo code availible to drive stepper motors though, whereas a clock requires a moer technically advanced approach. It's also ~single digit $ cost for a cheap servo.
>>8076162
I don't think i can solve the code by myself anyway. But there is a robots lab in my uni, they'll probably know wait to do with the thing right?
also, how much would think this will cost in total. I checked the prices of alduinos but they have several models with diff. prices. Can you give me a specific model?
>>8076173
If you manufacture everything you can yourself, using scrap stuff, I'd say up to 100$ + sweat + tears + blood
>>8076208
ahahha wow, i dont think i have knowhow to produce those materials. So I'm more inclined to buy the listed stuff from the earlier post.
Anyways ı think ı can manage up to 200's as far as my budget go. The anduino materials don't seem to cost much but I don't know about the angle sensors and servo motors and the power supply.
>>8076215
I meant all the mechanical stuff + buying all that electronics stuff and bearings. But nigga, listen, you gotta some steep as shit learning curve to do or find some tech nerd.
>>8076237
yeah, i know. I already started looking for a someone to help me out with. Honestly, I was expecting some elaborate system involving levers and cogs but turns out everything's digital nowadays.
People here told me it's not really that hard to do if you know your stuff tho. You think this is advanced stuff really?
>>8076258
I don't really see how you could accomplish that using only mechanics. There is no simple way to control clock speed from outside.
This is easy and really fun stuff if you are into it. If you have no clue it might be too much ground to cover in short time.
What about a gear setup like a differential?
>>8076326
what about it?
I'm hoping I can find someone who can help me with it, because I really don't have enough time to learn all about this stuff.
I just hope it's not that big of a task, because I'll be asking for favors and people usually prefer helping with the little stuff. I cannot really employ or engineer or anything you know.
>>8075887
Don't know if it's been said yet, but you want a differential gear.
https://www.youtube.com/watch?v=K4JhruinbWc
>>8075977
>arduino
whaddafug just use a differential gear you ape
is /sci/ seriously this retarded?
>>8076335
The central gear speed should be based on the difference of the outer two, which allows one crank to speed it up and one to slow it down. The challenge is connecting that gear to the clock mechanically.
>>8076375
>differential gear
>simpler than a toy computer.
>>8076387
Yes?
It's literally four fucking gears meshed together, this is ancient greek shit
A damn sight cheaper than fucking around with rotation encoders too
>>8076378
It'll just attach to the winding on a mechanical clock, ezpz
>>8076375
Do you know how differential works? How are you going to hook it up to a clock? You probably don't realise how complicated and expensive that would be, so I tell you: it is absolutely impractical and unnecessary overcomplicated.
>source: I'm and engineering guy
If you still don't believe that, draw a functional scheme, how you would realise your idea.
You can't.
you people suggesting digital solutions are half-assing this. You can solve any mechanical problem with a computer and enough motors, why are you even suggesting this bullshit.
If OP just needs any solution, then yeah, go for a computer. But I bet there's a good mechanical solution that would be way more satisfying to work out. Surely there are mechanical engineers who can offer some interesting solutions.
What about a using a flywheel?
>>8076396
use it how?
>>8076402
each crank could accelerate the flywheel in opposite directions, and the flywheel determines the speed and direction of the clock
What you want is a differential. Input 1 will be person 1, input 2 will be person 2 and the output will be the clock hand.
>>8076396
Mechanical clocks have complicated escapements, there is no easy way to control the clock speed.
>You can solve any mechanical problem with a computer and enough motors, why are you even suggesting this bullshit.
You would be surprised how much cheaper and more reliable are these sort of solutions in engineering. Just compare ancient cam driven automatic lathes with modern cnc ones.
Simplicity, rationality and cost are the names of the game.
>>8076372
>>8076389
>>8076391
>>8076395
alright that video kinda solves my problem. But as far as i can understand it, when the two wheels are running against eachother, there is real power struggle between the them. I mean considering I'm gonna make people use these cranks, they will try to overcome eachother using brute force. That is really interesting. What sounds a bit complicated to me is can anyway build this thing, or can I buy this cogs from anywhere. If so,I will just attach cranks on each side and use a rod to with a cog to connect it to the winder of the clock.
I guess the q is, which one is easier for a me to handle? I don't know anything about either of them tho.
>>8076407
So, how the clock will run when no one is turning the crank?
>>8076395
Are you fucking retarded?
Two input shafts to differential.
Spider gear rotates.
Spider gear drives a second gear.
Gear drives shaft.
Shaft connects to clock gearing.
Whole lot of fucking brainlets in this thread, my god
You're not an engineering guy, you're a pre-ancient greek retard
>>8076414
Not based on force, based on speed. The gears dont directly oppose eachother. The rate of rotation of the clock will be as a ratio of the input speeds.
>>8076417
This was never a design goal, OP just wants a gear competition
>>8076419
How is the clock running when no one is turning the cranks?
>>8076411
I agree, but the right mechanical solution can be much cheaper and simpler. It's always worth considering before jumping to the obvious solution. You don't need a computer in a door knob or a chair, you might not need one here.
>>8076423
It doesnt have to fucking run when nobody is turning the hands, that isn't a goal of this project
You could, however, have a motor drive a shaft and then have a second differential connecting the manual dif. output with the motor output to create a combined output going to the clock.
>>8076423
well actually a simple clock would run without the gear with its internal battery. Also I don't need to keep time with the clock that one persons tries to keep it from advancing while the other tries to make it reach a certain mark (15 mn to be exact)
Also ı just wanna remind everyone that one person should be able to rewind the clock with the first crank, while the other to force it to advance. the conflict here is between the to persons trying to beat eachother. İf the clock reach 15mn, the advancing crank wins. Otherwise the one keeping it from reaching that goes on with the game.
>>8076439
This is possible with a differential.
If forward is turning at the same rate as backwards is turning, no progress is made.
If either is turning faster than the other, the clock advances in their direction.
>>8076448
that's it then. I think that solves my problem. I mean aldunio solution is still viable if you ask me. But considering it is easier for a layman like me to get find way to produce the diff. gear, I guess I'll be going that direction. It's easier to understand how that one works and I won't be needing coders and everything to build that.
So where do I start. Should I go to a car mechanic or something to ask for these type of stuff. Or do I need a metalworker of some sorts to make me one?
>>8076468
just cut some wooden gears out with a saw
Your trying to reinvent the wheel
>>8076471
Can you guys suggest a link for a simple gear box for this purpose, Google keeps showing me very advance versions with way more cogs that I think I need to have.
>>8076468
Well, I misunderstood the initial problem, the rude fucker who attacked me is right, the differential is suitable for this application:
https://youtu.be/s1i-dnAH9Y4?t=755
This is what you might use.
Anyway, if you want a nice looking, robust mechanism using gearing will cost you way more than going with arduino. Just saying.
I like the mechanical solution, because it would look a lot more elegant and naked in it's essence.
>>8076512
You nigger, just use a dc geared toy motor.
The voltage is proportional to rotationion speed. It's around a few dollars.
>>8076498
Things kinda heated up there for a sec but that happens a lot here. I realize it might cost a bit more to get this gear box but I'm with you on its elegance. People would be more intrigued to inspect it if its done that way. It's for entertainment after all.
>>8076512
Heh, you don't know how stupid I get when it comes to these thing dude. I just wanna be sure before starting to ask around or go buying this shit. So if you have any schematics or diagram that directly corresponds to what I need, please do share.
You guys are really helpful btw, I really appreciate it. I'm sorry for asking to much but I just need to be sure.
>>8076522
>turn motor fast
>motor is kill
>>8076498
btw, it starts at 12:30 what you neeed
>>8076523
should have asked /diy/ desu
you wouldnt have ended up with the arduinoshit from these spazlords
>>8076548
Thanks man really appreciate it.
hail /sci/, I bow before your wit.
>>8076468
Legos
>>8076633
yeah this anon is right, lego makes differentials
>>8076642
wow, that is interesting. Are they any good. If this breaks down during show, it will upset a whole bunch of people.
>>8076672
test it before you do it
A golf or RC car differential will work
