the motors wont even be on the machine till everything is running right. I
run machines this size all day at work, so im pretty familiar with what i
can and can't do with them. all of the original contactors or relays or
whatever you want to call them are still in place in the control cabinet,
and i will use it all, no worries there.
with these motors im not looking for step direction, i want to use stepgen
to switch the 4 coils, thats why I'll use a higher step mode, like 5 or 6.
I was thinkin about just usin NPN transistors from the parport to switch the
coils. if i end up killin the parport by not usin optoisolators, big whoop
ill use a different computer to play with. i will use the diodes to keep
rid of the inductance problems. and it being a headache; its a hobby, so im
not in any massive hurry or anything and it keeps me entertained in the time
while the wife's at work (FREEE!! time) and it might even make some smoke
and get rid of some of these old computers i couldnt turn down.
BTW, what kinda cutters you usin / breakin? 3/4 inch end mills can plow
through quite a bit. :-D
On Tue, Feb 19, 2008 at 1:16 AM, Rob Jansen <[EMAIL PROTECTED]> wrote:
> Jim Coleman wrote:
> > I've got 3 little steppers that i want to use, they're 5 wire and i
> > believe bipolar? if anyone knows where to find datasheets for teac
> > 14769070-30 motors from old 5 1/4 floppy drives, i'd sure like to get
> > a copy. i know the motor is tiny, i'm only using it for a toy, might
> > push a table around with laser or maybe a sharpie, something of that
> > nature.
> >
> > I figure it'll be easy to build a simple little set of switching
> > transistors to run the motors from the parport output, using step
> > type... 6? maybe? im not doing so well interpreting the figures in
> > the integrators manual.
> Controlling a 5 wire type stepper motor is fairly easy, there is one
> common and 4 coils. You'll have to figure out what the common is,
> something you can easily do with an ohm meter (mayby this helps:
> http://www.doc.ic.ac.uk/~ih/doc/stepper/others/example2/<http://www.doc.ic.ac.uk/%7Eih/doc/stepper/others/example2/>
> )
> You could something like the schematics as shown in the two-wire
> connection diagram found at this page:
> http://www.doc.ic.ac.uk/~ih/doc/stepper/control2/connect.html<http://www.doc.ic.ac.uk/%7Eih/doc/stepper/control2/connect.html>but
> you
> will need to add some logic to do the conversion of the coil exitation
> sequence to step/direction signals. Google around will give a vast
> amount of links with stepper motor controllers.
>
> Just make sure you start at low voltage/current settings since these
> small motors are not meant for higher currents (it would be nice if you
> still have the original controller board of the drive to check the
> current).
>
> > after i get that set up, I'll need to build somethin to do the
> > switching from the parport. I really need to do some reading on using
> > transistors, i got into them slightly years back, and everything i did
> > have sunk in has floated away. I dont think these motors will draw
> > much current, they're pretty small.
> Just make sure you have protection diodes installed. When you remove the
> power of a coil you'll get a voltage spike on it's terminals and even
> with smaller motors these may damage your transistors.
> When selecting transistors you could use simple MOS-FETs. The IRF 7403
> (http://chipdig.com/datasheets/parts/datasheet/232/IRF7403.php) is an
> SMD component, but most pins can be soldered together. I use these
> little thingies to control high power LEDs at 350 mA, use the simple
> schematics as given in figure 10a in the datasheet - just make sure you
> install an extra diode accros the D-S connection, should be a schottky
> diode like a 1N5819
>
> But it may be a lot easier to just buy a set of motors with controllers.
> May save you a lot of head aches and damaged components.
> > I figure this little project will be a good experience before i'm
> > diving into a mesa m5i20 with my hitachi seiki VMC, with 1.3 and 2.8KW
> > servos and a 7.5hp spindle
> Yes indeed, that project is a little too powerfull to be used for newbies.
> I'm a newbie too - in CNC machining that is, I'm an electronics/computer
> engineer for about 20 years by now - and mistakes do happen.
> My machine has 250 and 500 W stepper motors and a 2 kW spnidle and I
> make sure I stay close to the E-stop button (an external E-stop, the ESC
> key from Axis is not enough as you can read in another thread) and out
> of range of the spindle motor.
>
> When starting up your big machine for the first time, use a virtual
> milling cutter and try to imagine what will happen. Next use a simple
> cutter (a cheap one - it may break) and use a piece of foam as 'subject
> under torture'.
> And do NOT operate your machine without limit switches and an Emergency
> stop on motor controller and spindle.
>
> I am now playing around with my machine for about three weeks and I
> started milling in foam (the type being used for isolating the roof) and
> MDF 'wood'. Meanwhile I ruined 3 cheap cutters, one just because I
> forgot to home the Z-axis after changing the cutter and the other two by
> underestimating the power of aluminium ...
>
> Good luck,
>
> Rob
>
>
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