Input Needed

[c02cutter]

I'm lost but have an idea. What I want to do is to drive a stepper motor without a computer. This project will require a cycle start input, have the motor run down to a limit. Reverse and come to rest at home position waiting on next cycle.

I'd like some input on how to set this up, without a computer, and relatively cheaply. Mechanically I can handle hands down. It's the electronics that I need help with.

Thanks for any help you can offer.

Eric

[keebler303]

Does it have to be a stepper motor? This sounds like a good application for a brushed DC gearmotor, a couple diodes and a couple limit switches.

If it needs to be a stepper motor I would look around for a circuit Mariss of Geckodrive made. It is basically a pulse engine with accel and decel ramps. It is somewhere in the electronics forum I believe. If you don't need accel and decel, then a simple 55 timer circuit could give you the pulse train and you would only need a couple switches to flip the direction bit and stop the step pulses from reaching the driver.

More details about the application would allow a more concise answer.

Matt

[c02cutter]

Basically just a Because can crusher project. Don't want to run pneumatics due to it going to be in the house. Possible for app for a gear motor. But would also like to know about how to set it up with stepper motor.

Concept, insert can close lid actuating the go switch... (kid proofing a bit there) spinning ball screw drives ram to limit, motor reverses and comes to rest waiting on on next cycle.


I do know that it my not be practical. But I do have a few reasons behind the idea.

1. Kids job at house is to crush cans...

2. Kids thing manual crusher is too much like work.

3. Trying to make it interesting for them to a point.

4. Lazy damn kids... lol

Actually at first I'll be doing just a experimental one to play with. Eventually want to make a completely closed unit that all moving parts are out of reach. I run an industrial laser cutting shop, so most of the fab is a cinch for me.

[keebler303]

Do you know how much force is needed to crush a can? Then how big a stepper motor you need to get that force? I think it might be asking a lot from a stepper motor. Did you look for that pulge generator I mentioned? It would let you send the proper pulses to a stepper motor driver which would turn the motor.

For this application, I would try to find a lift motor off of a treadmill. They are used to make the tread inclined. I have seen them before at Surplus Center. They have a beefy little motor and 2-3" of travel. It looks just like a standard acme screw so you should be able to put in a longer screw. I think they are rated around 800 lbs or so. You might also want some type of pretection to keep from burning up the motor if there is a jam or something. If the ram never reaches the limit switch it will just keep groaning until it dies. This could easily happen by putting in a second can before the first was removed.

I too have thought about a can crusher for the garage. I was invisioning a traveling ram which would be propelled using a small shot of butane and a grill ignitor. Insert can, push charge button, push fire button, remove flattened can.

While I'm on a tangent, it would also be pretty neat to make something that would seal to the top of the can and use a vacuum to suck the can flat.

Matt

[andypugh]

Originally Posted by c02cutter I'm lost but have an idea. What I want to do is to drive a stepper motor without a computer.

I know you say "without a computer" but by the time you have worked out the sequencing, interlocks and pulse generation in hardware, you will have spent more money and a lot more time than it takes to buy an Arduino and do it all in a reconfigurable way in software.
You would also need some sort of power amps, 25mA doesn't get you very far driving a motor, but that could be very simple running the motors unipolar.

PWM control of a DC motor might be easier, and would be a simple software change not a complete tear-up and rebuild of your circuit.

[neilw20]

You need some fun.
Make a small pile driver.
Wind it up. Bang!
No electronics or power needed.
See through plastic protection so you can see the destruction.

[GeeksGoneBad]

I have been working on some similar projects (driving steppers without a computer) and I've built a few circuits (sorry no schematics) that work

but without a microcontroller (I'm using a Parallax Propellor) I think it might be hard... the basic circuit I built used a 555 timer pulse to a L297 and L298 - but that would only drive the stepper when I pressed a button - not drive it to a location and stop then reverse - I think for that you'd want a microprocessor - then it's probably be pretty easy

Not sure how deep you want to get into electronics, but the Propellor is a great chip to work with

by the way - my projects are going to be trying to build some animatronics for like Halloween or Christmas

[whitehedr]

Arduino might be. what you need. You can get an Arduino UNO and a motor shield for abot 60 bucks. You would need to write a little program to make it work. Not a hard program to write but you would have complete control of the cycle. I have been thinking of how to do a can crusher myself. Nothing on paper yet. I am thinking of using the motor to drive a wheel connected to a ram. Kinda like a steam locomotive only in reverse.

RWW

[JacoMuller]

I have done a few projects withe steppermotors and small control boards. I have done last month with two steppers working together. Send me an e-mail and I will send you the parts list and Board info

[neilw20]

OK. I still reckon a pile driver is simple with and electric motor.
A chain with a hook pulls up the weight.
When at the top the weight falls off the hook.
The hook leans on a limit switch and turns off the motor. The chain has 2 hooks so it never sleeps.
Press a button to jumper the limit switch, in series with a door switch.
And it'll cost almost nothing for old bicycle chain bits and a door winder motor.
Kids will still think it is good fun.
As for the electronics, that's what's in the PC power supplies (2 in series) to give 10V at heaps of amps. They come from the junk pile too.

Some more crude electronics. Something to make it stay on for more than 1 thump in a cycle, and a door lock solenoid. All made from junk.
I might even make one. It will improve my woodworking skills.
I know the 84 year old neighbor (who collects cans) would use it.