Re: How can you test a stepper ?

Hi Ballendo,

sounds simple, but can you figure a way to make it cheaper for us
home brew cheapskates ? : )

I can envision that a center axis, with a pair of tacks/nails/screws
on a 3" bolt circle and a second set on a 4 inch BC would allow one
to set the pos/neg for each coil, then one could add a board in the
center axis with shunt from 3" to 4" so that as one rotated the
wooden board with shunt, it closed each pair of contacts. Maybe add
some playing cards and clothes pins to it clicks as you spin it.

Very good and simple idea.

Dave





--- In CAD_CAM_EDM_DRO@yahoogroups.com, "ballendo <ballendo@y...>"
<ballendo@y...> wrote:

> Dave,
>
> If these are 5,6, or 8 wire motors, you can test 'em with my simply
> made Graphical Universal Unipolar Tester (GUUT, pronounced "goot")

<g>

>
> You need a pine board (or short piece of 2x4), some paper clips,
> thumbtacks(without paint, and made of metal-in other words, CHEAP)
> Some hookup wire (#16-22 or so), and 2 "D" batteries (optional: 4-
> 1n400x series diodes needed for 2 phase on and half step testing)
>
> You can use drywall screws instead of thumbtacks. Nowadays the

screws

> might be easier to get than the thumbtacks without paint.
>
> Now we'll breadboard:
>
> Open six paper clips to 90 degrees(pull the small "loop" up form

the

> big loop outside it). Put the batteries on the board in series(as

in

> a flashlight), and use 4 of the 6 paperclips as "brackets" to hold
> them in line, holding them down with screws or thumbtacks. Fasten

the

> other two paperclips to the board so that they provide contact to

the

> batteries ends. Put a 12 inch or so piece of hookup wire under the
> tack or screw on these two clips, before you tighten it down.

You've

> now completed your GUUT stepper tester power supply!
>
> Next we'll build the translator/phase select portion. This section
> will be capable of wave drive, and one phase or two phase on full
> stepping. It will also allow half stepping. It uses an
> advanced "wetware" translation device :
>
> Put 4 screws or tacks in the board in a row about an inch apart

from

> each other(again put 12 inch or so hookup wire under these before
> tightening. Now open 4 paperclips 150-170 degrees, and arrange them
> parallel to each other, such that the big loop end is over the

screws

> you just placed. Next begin fastening the small loop ends of these
> clips. Before fully tightening them, put either a short wire under
> each fastener, OR one end of a diode. Be sure that you put the
> same "end" of each diode towards the clip.(the diodes have a "band"
> at one end; be sure all these bands are either towards the switch,

or

> point away from it.
>
> If you have used diodes, then attach the 4 short wires(3inches or

so)

> to the other end of the diode by twisting the two together. Now

bring

> all of these 4 wires together, AND one of the battery ends, and

twist

> them so that they maintain contact with each other.
>
> Your GUUT is now ready for use!
>
> Note: The diodes are not necessary for testing whether a motor is
> good or bad, only for playing with "advanced" half-step and 2phase

on

> stepping techniques.
>
> Using an ohmmeter (or mfr. specs), determine which of the wires is
> the center tap in the two motor coils. Connect these two motor

wires

> to the GUUT battery end which is not already connected.
> Now connect the other 4 wires (6 wire motor assumed) to the wires
> coming from the GUUT paperclip SPST "switches".
>
> The motor at this point should be "locked up". adding a masking
> tape "flag" to the shaft can be helpful.
>
> Now, if the motor is good, "SOME" combination of tapping the 4
> switches will make it turn correctly in one direction. If you

number

> the switches 1-4, it will make the discovered pattern more remember-
> able... (If no combination makes the motor turn consistently,

either

> you have a bad motor, or you used diodes and you need to reverse

your

> batteries in the "holder"...)
>
> start by trying the obvious, which is 1-2-3-4,1-2-3-4... If this
> works, then try 4-3-2-1,4-3-2-1... and the motor should turn the
> other way, also smoothly
>
> If not, keep tring combinations (one switch activated at a time),
> until you get one which works. Let's say you have found that 3-1-4-
> 2,3-1-4-2 works. Now try 2-4-1-3,2-4-1-3, and the motor should
> reverse.
>
> At any rate, if you can find a combination of switch presses which
> make the motor turn correctly, you have shown that the motor is
> GUUT<G>.
>
> For the next part, you may want to reconnect the motor so that the
> weird combination you have found becomes 1-2-3-4. What I mean is,
> using the example above, where 2-4-1-3 worked: move the motor wire
> connected to 2, to switch 1; the one connected to 4, to sw2; the

one

> connected to 1, to sw3; and the one that was connected to 3, to sw4.
>
> As a side benefit, you now have the motor leads identified for
> hooking up to a commercial drive<G>
>
> Any way, now you can try some other stepping variations (if you

have

> included diodes in your GUUT).
>
> What you have done so far is called single phase fullstep wave

drive,

> or just wave drive. That is, 1-2-3-4,1-2-3-4. This is used for high
> speeds, but has less torque than:
>
> Two phase on, fullstepping, which is: 12-23-34-41,12-23-34-41
> (pressing two switches at a time) Going the other way is 41-34-23-
> 12,41-34-23-12
>
> You may or may not be able to tell that this 4 step sequence is not
> giving the same step positions as the wave drive 1-2-3-4 that you
> used first.But that difference is what allows us to:
>
> Half step. Which is 1-12-2-23-3-34-4-41,1-12-2-23-3-34-4-41, and

its

> reverse; to go the other way.
>
> Es GUUT, yah?
>
> Ballendo
>
>
> P.S. I've had a bit of fun here, but what I have described is a

quick

> and easy way to not only see if a motor works, but also to

viscerally

> understand what a stepper driver is doing. When you are the
> translator, and can feel your fingers tappingout the step

sequences,

> it is amazing how much clearer these basics become...
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude
> <davemucha@j...>" <davemucha@j...> wrote:
> > Interesting idea.
> >
> > Some are hard to turn, some easy.
> >
> > all lock up tight when just connected to the Gecko, even without
> any
> > steps. I assumed that was an indication of good operation.
> >
> > Dave
> >
> >