--- In
Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:
> I see..
> all say: most important: KEEP IT SIMPLE.
>
>
> It just hapens i have some of this Molybdenum grease (in a spray
can)
> here. So i will use it.
>
>
> The motors, again...
>
> I wonder wich power the steppers should have.
> 200 steps is ok?
> Most motors are rated in volt / ampere....
> I know it would be better to compare them by N/m but the ones
> i have are not labeled in torqe...
>
>
> I have some, but they are too small i think...
> So please anybody having firsthand experience please tell me what
is
> needed.
>
>
> I also wonder if the main axis should be driven by one or two
motors.
> If there is only one motor the screw is centered. or two screws are
coupled
> by tooth belt... isn't there the problem of carriage skew if the
spindle
> is centered and the load applied on one side only?
>
>
> thanks
> st
The first answer is usually a question. what is the size of the load
you want to move ?
if all you are doing is a drilling platform, then your little motors
are probably good enough.
Remember the loads to move a board are not much different than to
move a printer head.
I am not a motor expert, but have figured out that there are mainly
two versions of stepper motors.
the pressed can style. these are the ones you find in small printers
and such.
then there are the NEMA rated ones. NEMA17 is 1.7 inches square on
the mounting plate
NEMA23 are 2.3 inches square and NEMA34 are 3.4 inches square.
a NEMA23 is common in laser printers are other machines so you should
be able to find them as surplus for not too much money.
Often 200 steps per rotation, with half stepping, you get a decent
400 steps per rotation.
pleanty strong enough for light wood routing, very light aluminum
milling and more than enough for a drilling machine.
Stepper motors are rated for voltage and amps.
You can run them at rated voltage for minimal power, or use a chopper
style driver and use a MUCH higher voltage. using 20 times the
nameplate is very common. in fact if you check a data sheet, your 5
volt motor will show performance with a 48 V power supply.
Of drilling only considder a solenoid for the Z axis. for routing,
you can use a solenoid or leadscrew, but for milling, you need to use
a very solid machine. adds to the complexity and cost. and that is
one reason I am interested in a drill only version.
HTHs
and please post more questions. we all need to review.
Dave