Laser stepper help: easy, cheap, smal!

[funtasma]

Hi all.

I several times found some posts of people new to DAVID who had theier difficulties with the stepper motor technic. While searching for some basic specifications for floppy stepper motors I found a genius tutorial about how to use the smal stepper motors of 1.44 MB Floppy drives.

It describes how you can make use of the stepper controler of a floppy. This is so easy, even the new ones here can follow the tutorial and for only EUR 10,- you get a floppy drive that comes with a stepper motor and the controler and you don't need to make your hands dirty!

That's cool. here is the link:

All you need in addition is a gear. I use the "VARIO-GETRIEBE-BAUSATZ" which you can order from conrad.de
, if you live in Germany.
Just replace the small motor from that set with the stepper and thats it (in my case the stepper axis fits exactly to one of the many gear wheels that are comming with the set). But I'm sure you'll find similiar sets of gear boxes in other countries as well.

Have fun with it!

-Benjamin-

[Bongobat]

Hi Benjamin,

Nice find. Okay I did not know all the floppy drive needs basically is step and direction. So also rather than using the parallel port you could use the DTR and RTS line of the serial port via a usb adaptor. Yeah everyone knew I was gonna say that huh. Im not so sold on the idea of using the computer to generate the timing sequence for the laser movement though. You may need to have your program running at high priority to keep a constant pulse and then you never know if it is constant. Might work good if you do not need planeless scanning. With the USB adaptor you could even use sync pulses from david directly Im curious,What was the step angle of the steppers in your drive?


Why is it you can never find something till you need it? I had an old floppy disk drive somewhere ugh

EDIT: Also the "speed limit" of the DTR/RTS toggel may not make my idea so great. Another alternative is of course to simply use a couple of pins of an arduino. I found a floppy dirve on ebay for $8.25 with shipping free! This does seem to be a cheap alternative since motor and controller are bundled.

Thanks,
Greg

[funtasma]

Well, the stepps are quite rough. The little motor has only 30 steps, makes 12°. So the gearbox is unavoidable.

Actually I don't use the parallel port for my scanning device, but I experienced allready with an other stepper controler, that the parallel port of windows driven machines can often cause missing steps. I use the Velleman k8055 USB-board. It's quite relyable and has many options to play with. It's available in whole Europe, but I have no idea if they sell outside Europe as well:

But what I really like is that programming is very easy for it. It comes with an easy to understand dll in VBA.

-Benjamin-

[Bongobat]

HI,

After I took apart a working floppy drive from a computer I then easily found the other one I wanted to use HA. Okay I have 2 to play with now. I noticed something weird. Both drivers have 5 volts on the Direction and Step pins. So instead of the ardunio sourcing 5 volts I had to sink it. Okay it was easy to test since I already turn my laser/slide projector on by sinking them to ground with an ardunio and a IRF540 mosfet. I just connected the floppy step pin to the laser/projector ground pin. The ardunio and floppy were powered by a PC power supply. I programed a little sketch that pulses on the laser arduno pin.

The floppy controller has an optical end stop switch and this is where it gets weird. If I power on the floppy drive without a piece of metal between the stop switch and give it a pulse train the motor will turn in a counter clockwise direction. If I ground the direction pin the motor just stops and hums. If I cut power to the floppy drive and insert a pice of metal in the stop switch and then turn it on the motor will turn in a clockwise direction indefinitely and then if I pull out the metal it wil turn in the counter colckwise direction indefintely. But if I put the metal back in then it will stop. Okay if I power up the floppy with the metal in the switch and then ground the direction pin the motor does not change direction but if I remove the metal like i said before it does change direction then if I insert the metal again it will stop and then if I ground direction button it will move like 8 steps and stop. ????????? I also had a sequence that i forgot now where i could run the motor clockwise and then ground the direction pin and it would step backwards like 8 steps and stop FRUSTRATION! Obviously there is only one answer: These things are possesed by demons! Okay so maybe the real answer is that these are not just step/direction controlled stepper controllers their must be some kind of other logic going on. So these are the two I had and they worked similar. Do I just have weird drives? or maybe the codeproject guy got lucky with his floppy drives

The steppers are very small and only work correctly when the end of the shaft is pressed up against a bearing . Benjamin can you please show a picture and describe how you attached your motor to the conrad gearbox?

thanks,
Greg

[WalterMo]

Benjamin,
I notice that you like to tinker with used or cheap components. Do you know Pollin, a German seller for odds?
http://www.pollin.de/shop/index.html

On this site they have stepper motors. But currently nothing very suitable for us:
http://www.pollin.de/shop/p/OTk0OTg4/Mo ... toren.html

Walter

Edit: Have just discovered at Pollin this stepping motor with gear for 4.95€. Seems to be very interesting:
Schrittmotor JAPAN SERVO KH42JM2-038

[funtasma]

I'll post a photo. Unfortunately I'm too busy now. I have still a pile of work on my table before Christmas. And funny enough...Christmas seems to come out of sudden and as every year I wonder how to manage every thing before that sudden event. If I only would have known before that a holyday pops up I would have been prepared better....

Merry Christmas to everyone!

-Benjamin-