stepper construction

[Jon Kirwan]

I'm interested in the idea of actually building a stepper and
I'd like to know if anyone knows of companies selling
hobbyist quantities of parts for doing that. Laminations,
stators, rotors, etc. I found one in Switzerland, but it's
not a complete supplier of parts and I'm not sure about their
ability to sell hobbyist qtys.

I'm mostly interested in doing this to learn, though I may
use the results as well. I would like to try building
unipolar PM and hydrid types. I'm interested in prediction of
performance, given a physical design, too. So details on that
would be intriguing, but not necessary. I can play and just
find out what I get as a result. Most steppers are prebuilt
units, for hobbyists. I'd like to actually assemble and wind
some by hand.

It's a "highly technical sale" and I'm sure there are very
few companies that want to step into this mire of horrible
after sale customer support, for no decent profits. So I know
why there would be few, or none, doing this. So any supplier
names would be very much appreciated as I expect them to be
as rare as hens' teeth.

Perhaps there is a club doing this kind of thing where I
could piggy back on purchase orders?

Thanks,
Jon

 

[Bob Masta]

I'm interested in the idea of actually building a stepper and
I'd like to know if anyone knows of companies selling
hobbyist quantities of parts for doing that. Laminations,
stators, rotors, etc. I found one in Switzerland, but it's
not a complete supplier of parts and I'm not sure about their
ability to sell hobbyist qtys.

I'm mostly interested in doing this to learn, though I may
use the results as well. I would like to try building
unipolar PM and hydrid types. I'm interested in prediction of
performance, given a physical design, too. So details on that
would be intriguing, but not necessary. I can play and just
find out what I get as a result. Most steppers are prebuilt
units, for hobbyists. I'd like to actually assemble and wind
some by hand.

It's a "highly technical sale" and I'm sure there are very
few companies that want to step into this mire of horrible
after sale customer support, for no decent profits. So I know
why there would be few, or none, doing this. So any supplier
names would be very much appreciated as I expect them to be
as rare as hens' teeth.

Perhaps there is a club doing this kind of thing where I
could piggy back on purchase orders?

Thanks,
Jon

As an alternative, how about tearing down old steppers for
parts? Old 5.25" floppy drives are one place to find them.
The driver circuitry is right there as well, which might
simplify some of your experimenting. There used to be (and
probably still is) info on the Web about how to tap into it.

Some years ago I built a simple robot from a couple of old
drives, as a project to work on with my then-young nephew.
Mounted the steppers from both drives on one chassis, axles
sticking out on either side, installed wheels on them,
mounted the second controller board atop the first, and
wired both to a long cable with a printer port connector on
the other end. (Plus an old PSU.) Simple commands in BASIC
operated the steppers independently or together for
steering, etc.

The nephew had a blast, but is going into automotive
technology instead of robots or programming... oh, well!

Best regards,


Bob Masta

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[Jon Kirwan]

As an alternative, how about tearing down old steppers for
parts? Old 5.25" floppy drives are one place to find them.
The driver circuitry is right there as well, which might
simplify some of your experimenting. There used to be (and
probably still is) info on the Web about how to tap into it.

I only have a couple of 5.25" floppies and I want them to
keep working. I suppose I could go to a computer junking
place and see what I could come up with. But eventually, I'd
like to build up some Nema 42 frames for some practical
applications. So that is where I'm headed in the end. And I
won't be doing that with floppy motors. So eventually, I'd
need a supplier. Though certainly I can do a lot of learning
before that time.

I could also just buy steppers and tear them down. But I'd
really like to find a supplier. That's my big goal, right
now. But I just can't seem to find more than the one is
Switzerland. And they don't supply all the needed parts, so
they provide the kingdom that fails for want of a nail, so to
speak.

Some years ago I built a simple robot from a couple of old
drives, as a project to work on with my then-young nephew.
Mounted the steppers from both drives on one chassis, axles
sticking out on either side, installed wheels on them,
mounted the second controller board atop the first, and
wired both to a long cable with a printer port connector on
the other end. (Plus an old PSU.) Simple commands in BASIC
operated the steppers independently or together for
steering, etc.

The nephew had a blast, but is going into automotive
technology instead of robots or programming... oh, well!

Hehe. Maybe he decided he couldn't compete with you and ever
feel good enough about himself?

Anyway, still looking for a supplier. And thanks for any
comments, though. Certainly, worth considering until I do
find a few. (I can hope I will find them, perhaps.) Someone
has to supply the parts that are used by these stepper
manufacturers....

Jon

 

[Michael Black]

Some years ago I built a simple robot from a couple of old
drives, as a project to work on with my then-young nephew.
Mounted the steppers from both drives on one chassis, axles
sticking out on either side, installed wheels on them,
mounted the second controller board atop the first, and
wired both to a long cable with a printer port connector on
the other end. (Plus an old PSU.) Simple commands in BASIC
operated the steppers independently or together for
steering, etc.

I wsa thinking of doing something like that, only more like the "space
crawler" from Major Matt Mason. It didn't have wheels, it had four arms
coming out of the shaft, on each side of the vehicle, supposed to be
better for climbing over things. I imagined it might make sense to have
each side on its own stepping motor, so if stuck one could wiggle via the
other one.

Somewhat related, the regional science fair is happening here this week,
and as always, it gets no publicity ahead of time. By the time the news
covers it, it's too late to go and take in the event.

Michael

 

[Jon Kirwan]

Gearmotors would give you a lot more torque for the size of the package
than steppers.

(grain-o-salt: I dislike steppers for all but the uses where they are
shoo-ins).

I can use a DC motor, of course, _IF_ I add feedback
(optical, for example.)

As I understand it, open loop driving steppers works okay for
positioning (my application) with the money going into better
and better lead screws and backlash nuts. Up to a point where
the lead screws are costing LOTS of money to get the
increasing precision out of them. Then it's back to using
cheaper motors and expensive precision optical feedback
ruling for position control. Something like that, anyway.

Torque is great of course. But I'm positioning, as well. Open
loop with steppers, given enough torque for the job. Closed
loop won't require them, I suppose. But it adds another whole
element to the system.

(Shorter term I'm targeting a 12" x 18" x-y platform motion
with 10 micron positioning resolution, ±2 micron variation,
and perhaps a few kg mass. Longer term will depend on
successes there.)

I'd like to learn, though, if there are better ways to see
this.

Jon

 

[Michael Black]

Gearmotors would give you a lot more torque for the size of the package
than steppers.

(grain-o-salt: I dislike steppers for all but the uses where they are
shoo-ins).

Except I wasn't interested in real results, just the notion of using some
of the stepping motors I have lying around.

I remember the Steve Ciarcia column in Byte where he uses a cordless drill
for the source of propulsion.

Michael

 

[Baron]

Jon Kirwan Inscribed thus:

Just about every printer has one or more stepper motors, though the HP
ink jets tend to use brush motors and encoders. If you want really
powerful steppers grab an old photo copier.

 

[Jon Kirwan]

Or, if you're lazy, look to the surplus places. There always seem to be
steppers available (probably 'cause they were replaced by gear motors .

My favorites, although there may be better ones out there:

http://www.mpja.com
http://www.allelectronics.com
http://www.herbach.com

I'm gradually gathering that assembling your own stepper
"isn't done at the hobbyist level" anymore.

I definitely remember watching some club members building
their own DC motors for model aircraft -- magnet wire,
stators, etc., all laying on a table about the dozen or so
people sitting around trying their hand FOR THE FIRST TIME
making their own motors to whatever size they wanted. It was
very pleasant to watch. At the time, I wasn't involved and
didn't care so much. Now I do and now I'd like to be doing
that, as well, but with steppers.

Dismantling different motors will probably yield me parts
that won't go together right in the end. (Different frames,
etc.) And, at my level of ignorance right now, I'm not even
sure if I selected all of them with the same frame that I
would find I could make up a larger body without some want of
a "nail" that wouldn't be there. I suppose I could just go do
it. But a supplier of parts would be nice to know about just
the same.

But I'm getting the message. No one here knows of a supplier
for hobbyist qtys. Which, together with my google
difficulties finding one, I suppose says something. It's not
done by hobbyists now.

Jon

 

[Jon Kirwan]

To build a stepper for educational purposes, I'd suggest you get some tin
cans and some magnets, and get cracking.

To build your own custom stepper -- I think you're on your own. What do
you want out of a stepper motor that you can't get from an off-the-shelf
one?

Education and the ability to build a stepper that is
precisely designed for a specific application, no larger and
no smaller than exactly needed, once I learn enough to do
that.

Jon

 

[Jon Kirwan]

<snip>
Education and the ability to build a stepper that is
precisely designed for a specific application, no larger and
no smaller than exactly needed, once I learn enough to do
that.

The goal is the process of doing, and then doing better, and
then feeling a sense of accomplishment when finally able to
both apply theory and test the final result for conformance
to that theory and to feel a sense of "closure" about it.
It's a very nice feeling.

Jon

 

[Michael Black]

Jon Kirwan Inscribed thus:


Just about every printer has one or more stepper motors, though the HP
ink jets tend to use brush motors and encoders. If you want really
powerful steppers grab an old photo copier.

And you get the power supply too (which are often in the 20 to 30v range).
I'd also argue that the driver circuitry is more accessible than from a
floppy drive.

There used to be projects in the hobby magazines for using printers (I
guess theyw ere dot-matrix at the time) as the foundation of things like
plotters. Mostly leave the printer intact. Of course, there was also
that gadget for the Apple Imagewriter that looked like a ribbon cartridge,
but was a a scanner sensor, so you'd put the paper to be scanned into the
printer just like any other sheet of paper, and scan it simply by issuing
commands to the printer (I guess something like spaces to advance the
"scanner head" then carriage returns at the end of each line).

Michael

 

[Michael Black]

I'm gradually gathering that assembling your own stepper
"isn't done at the hobbyist level" anymore.

I've never heard of anyone making their own stepper motors.
Maybe way off in that direction, but never a mainstream thing if
it was ever done. Stepper motors were never a real mainstream
hobby thing, so there's less reason to build your own.

I definitely remember watching some club members building
their own DC motors for model aircraft -- magnet wire,
stators, etc., all laying on a table about the dozen or so
people sitting around trying their hand FOR THE FIRST TIME
making their own motors to whatever size they wanted. It was
very pleasant to watch. At the time, I wasn't involved and
didn't care so much. Now I do and now I'd like to be doing
that, as well, but with steppers.

Need may have been a requirement there. Making tiny motors that were
otherwise unavailable. Model building has been like that, the first
model airplane that wsa radio controlled was done with a ham license,
since there was nothing else, until the hobby became so mainstream that
a special radio service/license was created. That goes way back to the
thirties, and since it started early as a hobby, it wsa hobbyists who
built up the equipment. Likely the commerical manufacturers that
eventually came along were started by hobbyists who had the background and
saw a wider interest than just the ones who were building everything.

Of course, at one point, motor building was a hobby thing. I remember one
article in one of the hobby magazines were someone built endlessly small
motors in his home workshop. IN part to show he could.

Dismantling different motors will probably yield me parts
that won't go together right in the end. (Different frames,
etc.) And, at my level of ignorance right now, I'm not even
sure if I selected all of them with the same frame that I
would find I could make up a larger body without some want of
a "nail" that wouldn't be there. I suppose I could just go do
it. But a supplier of parts would be nice to know about just
the same.

But I'm getting the message. No one here knows of a supplier
for hobbyist qtys. Which, together with my google
difficulties finding one, I suppose says something. It's not
done by hobbyists now.

I don't think there were ever "parts to build stepper motors for
hobbyists". People tended to use surplus (which is the same thing as
taking apart floppy drives and printers), hoping to find something useful,
and if not, then they are buying off the shelf and paying the price.

There was a time when hobbyists were looking to hobby shops, I can
remember some articles in Byte about using servo motors from radio
controlled modelling for various things. They were trying for off the
shelf solutions.

Michael

 

[Jon Kirwan]

I've never heard of anyone making their own stepper motors.
Maybe way off in that direction, but never a mainstream thing if
it was ever done. Stepper motors were never a real mainstream
hobby thing, so there's less reason to build your own.

I'm not looking for "main stream." Back in the day, I built
three telecopes. It took me about 1-2 thousand hours each,
grinding and figuring the mirrors and some other work, too.
Not a lot of people were doing that, then. But enough that
there were hobbyist qtys of glass of various kinds AND
suppliers of same for hobbyists.

I don't think this is much different than that. Probably, the
market would be even bigger than it was for people making
telescopes. For one thing, the world's population was about
40% then what it is today, so you've already got a 2.5 factor
there. For another, I have to believe that NEMA 42's costing
$200 each would be a motivation and there are more people
interested in steppers than in telescope mirror grinding -- I
think.

I'm not arguing the market is big. But you used the phrase
"mainstream." Neither telecope making, nor stepper making,
would be mainstream. But that doesn't mean there cannot be
suppliers. There may be. There may not be. I was asking.

By the way, I do have ONE company doing it. Not for
hobbyists, looking at the web site. But doing it, at least. I
can, if they will sell to me, actually build up my own
steppers from stacks of parts, wire, and their prefabbed
magnet structures.

Need may have been a requirement there. Making tiny motors that were
otherwise unavailable. Model building has been like that, the first
model airplane that wsa radio controlled was done with a ham license,
since there was nothing else, until the hobby became so mainstream that
a special radio service/license was created. That goes way back to the
thirties, and since it started early as a hobby, it wsa hobbyists who
built up the equipment. Likely the commerical manufacturers that
eventually came along were started by hobbyists who had the background and
saw a wider interest than just the ones who were building everything.

I was there. It was about learning, mostly. These were first
time builders there, not because they couldn't buy such a
motor as they were building, but there because they thought
this was fun. I can assure you it was about nothing else.

Of course, at one point, motor building was a hobby thing. I remember one
article in one of the hobby magazines were someone built endlessly small
motors in his home workshop. IN part to show he could.

hehe. Well, I'm still looking. And I won't be discouraged for
at least another few months, yet. I will contact the Swiss
company, too, and ask them about buying as well as if they
can point me to some other companies who may be willing to
cater to me. Might get a helpful reply. Can no more than ask.

I don't think there were ever "parts to build stepper motors for
hobbyists". People tended to use surplus (which is the same thing as
taking apart floppy drives and printers), hoping to find something useful,
and if not, then they are buying off the shelf and paying the price.

There was a time when hobbyists were looking to hobby shops, I can
remember some articles in Byte about using servo motors from radio
controlled modelling for various things. They were trying for off the
shelf solutions.

I've seen the parts for DC motors being used in a hobby
class. (As mentioned.) So I KNOW for certain that someone was
able to get such parts for that purpose. I see no reason why
it's such a stretch from there to a stepper. Of course, I'm
not even sure I can find out who they used as a suppler for
the DC motors, either. But they stacked up as many stator
laminations as they wanted to. Like the following:

http://www.made-in-china.com/showro...a-Stator-Lamination-for-Shade-Pole-Motor.html

Which brings me to the point. These DO exist. People DO build
steppers. They may do them as a commercial business, of
course. But they DO get parts from SOMEWHERE. The issue may
be that I have to buy in bulk. But that often can be
finessed. I just need to find out WHO is doing this, who
their competition is, what their selling policies are, etc. I
can then work through the mail, phone calls, arguments, and
so on to achieve my goals. But I have to have someone to talk
to, to start.

Anyway, I'll keep looking for a bit. I was mostly curious if
anyone here had tried their hand and had some success at
this. Seems not. Which is fine. The only sure way of finding
out is asking.

Thanks,
Jon

 

[Michael Black]

I'm not looking for "main stream." Back in the day, I built
three telecopes. It took me about 1-2 thousand hours each,
grinding and figuring the mirrors and some other work, too.
Not a lot of people were doing that, then. But enough that
there were hobbyist qtys of glass of various kinds AND
suppliers of same for hobbyists.

But telescope making was "mainstream". Not as in "everyone was doing it"
but as in "within the niche of people who wanted telescopes, making your
own was a fair subset". There were endless books, there were places like
Edmund Scientific for the lenses and supplies, I imagine the astronomy
magazines had construction articles about making telescopes.

People made telescopes because there were all those surplus lenses from
Edumund, but the books and supplies also existed because people were
interested in making their own telescopes.

I don't think this is much different than that. Probably, the
market would be even bigger than it was for people making
telescopes. For one thing, the world's population was about
40% then what it is today, so you've already got a 2.5 factor
there. For another, I have to believe that NEMA 42's costing
$200 each would be a motivation and there are more people
interested in steppers than in telescope mirror grinding -- I
think.

I'd argue that in electronics, making components was mostly about
curiosity, except if you go back to the early days when parts were less
available.

So you'd see articles about making capacitors in Elementary
Electronics forty years ago. Nobody went and made their own capacitors
for their projects, they made one or a few to see what it was like.

I once saw an article about how people did things in the early days of
radio (this article was in the early seventies), things like using broken
pencils as resistors. Then there was a need, but once components became
cheap, the only time people made them was for curiosity.

I'm not arguing the market is big. But you used the phrase
"mainstream." Neither telecope making, nor stepper making,
would be mainstream. But that doesn't mean there cannot be
suppliers. There may be. There may not be. I was asking.

Making telescopes was way bigger, within the subset that was interested
in astronomy, than motor building was within the hobby of electronics.
Neither main hobby is "mainstream", but within the specific hobby, some
things are more mainstream than others. While I mentioned that article
about someone who made tiny motors at home, in terms of actual
construction articles the best I can remember was how to make a
rudimentary motor for the sake of demonstrating how electric motors work.

I'm saying motor building was never "mainstream" within the hobby of
electronics. The fact that the hobby magazines never covered the area
other than as a crude demonstrator motor is the indicator of that. That's
how you tell mainstream from niche.

By the way, I do have ONE company doing it. Not for
hobbyists, looking at the web site. But doing it, at least. I
can, if they will sell to me, actually build up my own
steppers from stacks of parts, wire, and their prefabbed
magnet structures.

And that's always been there, pay the price and you can get it. Hobbyists
aren't the only people in the world, there are prefessionals who need to
prototype something and off the shelf won't work. Just like that one
company offered a line of pots that could be combined endlessly to make
whatever exact type of pot you needed.

Michael

 

[[email protected]]

But telescope making was "mainstream". Not as in "everyone was doing it"
but as in "within the niche of people who wanted telescopes, making your
own was a fair subset". There were endless books, there were places like
Edmund Scientific for the lenses and supplies, I imagine the astronomy
magazines had construction articles about making telescopes.

They did. Many universities, observatories, and planetariums held
classes in mirror grinding, as well. There were several places where
one could send one's blank to have it aluminized and coated. Some of
the above classes used silver, as well (could be done without
expensive equipment).

People made telescopes because there were all those surplus lenses from
Edumund, but the books and supplies also existed because people were
interested in making their own telescopes.

I would bet that *very* few refractors were built by amateurs. They're
rather pointless.

<...>

 

[Jon Kirwan]

I endorse the "for education" part. I don't think you'll gain enough
expertise do really nail the "precisely designed for a specific
application".

And, since I'm biased against steppers, I think you'll do better with
some sort of a geared closed-loop solution for most applications. But I
freely admit that I'm biased.

I very well may have to go with that. But I'd like to explore
and learn. And if I buy everything premade, the learning
experiences will be ... very expensive. Plus, you only learn
how to _use_ something that way. You don't learn deeper
concepts because they aren't exposed to you, then.

Just to make it clear where I come from....

I'd rather spend $1000 buying tools and parts and making
something I need than spend $1000 to pay someone else to do
it. In one case I have some new tools and parts for later,
have learned a lot more than I knew before, and also have my
solution. In the other case, I pay someone else to do it,
learn nothing new myself in the end (though they may learn
something from doing it), but I get a finished end result. I
like learning and don't mind paying money and time for that.

(Even when I just can't succeed at it -- even then I've
learned something more and can be a much smarter purchaser
for that spent labor. Even failure is success.)

I'll give you a recent example to illustrate. I could hire
someone to build me a specialized door I needed (pocket door,
exterior style thickness, designed to withstand my profoundly
autistic daughter's pounding and kicking, with a top rail
strong enough to carry the door and a person hanging on it.
-- I actually need 5 of these.) Hiring someone to build a
custom door, or else compromising and accepting some mass
manufactured door, is what MOST people would do, especially
if they have never built a door before (as I haven't.)

I first shopped around (literally for a few months because
some of the dealers needed the time -- one of them took 3
weeks to quote a price, for example.) I called distributors
in other states (they aren't in Oregon.) I finally called the
few companies that ACTUALLY make the doors themselves (many
distributor roads lead to the same few places, it turns out)
and spent some good time learning about their processes and
capabilities. In the end, I realized it would have to be
custom to satisfy the necessary parts of my requirements.
Once I realized that, and the price for each door (approx.
$800 ea, delivered), I set out to make them myself. I bought
the necessary router and bits, various clamp types and
clamps, glues, sanders, and so on. In the process of making
these doors, I've learned a great deal and the result is
actually much better than I could have requested by custom
order. (I was able to custom design the rails and the hanging
hardware for it to make a perfect and extremely strong blend
that can support a hanging weight of 800 lbs for each door.)
These doors are stunningly beautiful, made from hard woods
and a custom interior fill, four rails, two stiles, custom
locking system, and custom hanging system. Took interior
walls down to the structural members and built it all back up
in the house. Myself. And I'm proud of the result. It's
really wonderful. And I learned a lot from doing it. I would
have learned NOTHING from having hired it done. I'd rather
spend the money on myself. I change. And that's what's
valuable.

Education is a lifestyle.

I'm looking to see if that is possible here. I have end goals
and don't need to include this process, of course. If it
isn't possible, then it isn't and I'll have to move on. I was
just entertaining the idea and asking for informed opinions
about the possibility. I have a few other lines out on this
topic, as well, and I'll see what I catch in the process.
Might get lucky. Might not. Either way, life moves on and I
won't look back. But this project is out about a year so I
have some time to dawdle a bit.

Jon

 

[Jon Kirwan]

<snip>
Years ago, when I first got interested in stepper motors, I learned
what I could from books and taking them apart. The hybrid steppers at
that time were magnetized after the motors were assembled.

Okay. That's interesting to note!! Thanks.

Taking a
motor apart would break the magnetic circuit and much of the magnetic
strength of the rotor would be lost. This resulted in a drastic
reduction of torque output from the motor when it was re-assembled.

For hybrids, right? (But possibly not in the case of some
others?)

Aside from learning that I also saw how the teeth machined in the
rotor and the teeth machined in the stator caused rotation when the
coils were energized in the proper sequence. And I was reading in NASA
Tech Briefs about a month ago about a new hybrid step motor design
that uses magnets in the stator to redirect the magnetism from the
rotor which increases available torque significantly.

Any links you may share?

Since I'm a
machinist I have some idea of what it would take to machine the parts
for a stepper motor and since I have rewound a couple simple motors in
the past I have some idea of how hard it would be to duplicate the
windings in a comercially made stepper. It would take many hours to
build a stepper from scratch and building one that is even close to
being as efficient electrically or volumetrically as a comercially
available one would be a full time job for quite a while. Good luck.

I would be hoping for "standardized" parts that are pre-made
to a specific frame size, but could be assembled into longer
or shorter motor structures. I don't have the equipment here
to build all this from scratch. (I have plate steel up to
about 1/3" thickness and can do some modest cutting and
welding, but no precision equipment for metal working.)

Please let us know how you do on your project. Learning is fun.

If I find some generous suppliers, I'll post it up. I'm not
expecting much. From comments here and the relative "hearing
crickets chirp" when looking for suppliers so far, it may be
the case that I've no reasonable options outside of buying.
But it would be a lot of fun if I could find just one
practical alternative where I get to assemble and wind my own
steppers.

Tim has also made some strong recommendation about geared DC
motors and I take his point and must investigate that side,
as well. I can fabricate custom gearing, including planetary
gear systems. Which then would leave open the idea of winding
my own DC motors, as well. A separate, but related question.
And in that case, I've actually observed hobbyists winding
their own for the first time. But it was years ago and I've
no idea how to track down their supplier. So I'd be back here
asking about that, as well.

It's all fun. Maybe I'll get a good bite at some point.

Thanks so much for your comments. Appreciated a lot!

Jon

 

[Jon Kirwan]

AFAIK that was being done about ten years ago by people who couldn't get
small brushless motors, but could rebuild motors from CD drives to work
at the voltages available on an RC plane.

The market caught on, and now a brushless motor the diameter of a dime is
fairly mainstream, as is the speed controller to drive it.

I'd like to learn something new. I'll keep looking a bit
longer before giving up.

Jon

 

[Jasen Betts]

Don't you need a special 'keeper' so that you don't demagnetize a
stepper motor when you take it apart?

AFAIK only AlNiCo magnets need keepers, I think most steppers use
ceramic or neodmyium magnets.

 

[Lawrance A. Schneider]

I'm interested in the idea of actually building a stepper and
I'd like to know if anyone knows of companies selling
hobbyist quantities of parts for doing that. Laminations,
stators, rotors, etc. I found one in Switzerland, but it's
not a complete supplier of parts and I'm not sure about their
ability to sell hobbyist qtys.

I'm mostly interested in doing this to learn, though I may
use the results as well. I would like to try building
unipolar PM and hydrid types. I'm interested in prediction of
performance, given a physical design, too. So details on that
would be intriguing, but not necessary. I can play and just
find out what I get as a result. Most steppers are prebuilt
units, for hobbyists. I'd like to actually assemble and wind
some by hand.

It's a "highly technical sale" and I'm sure there are very
few companies that want to step into this mire of horrible
after sale customer support, for no decent profits. So I know
why there would be few, or none, doing this. So any supplier
names would be very much appreciated as I expect them to be
as rare as hens' teeth.

Perhaps there is a club doing this kind of thing where I
could piggy back on purchase orders?

Thanks,
Jon

A few wooden yoyos, some scrap metal cut to size and a few magnets and a
few electro magnets and have fun.

Larry