[Marc]

Guys, started my first CNC router, mostly made out of alu, and a moving gandry type of CNC. The machine mesures 19''x12'' with a cutting area of about 12''x8''. Right now I'm starting to shop around for stepper motor but I'm confused about what I really need. Basicly I'm looking for stepper in the range of 60 to 80 oz of torque(will be using the CNC to engrave into plastic). But the thing I'm confused about is this

The number of wires(I see some on Ebay with 4,5,6,8 lead)
The number of phase
The voltage
Bipolar or unipolar

Like these ones have 6 lead but a 4 pin connector??And would they fill my needs?

http://cgi.ebay.com/ws/eBayISAPI.dll...DME:B:DS:US:28

Thanks a million
Marc..

[MrBean]

8 wire motors can be run as either "unipolar" or "bipolar, series or parallel".
6 wire motors can be run as either "unipolar" or "bipolar, full or half winding".
4 wire motors are bipolar only.

5 wire motors are unipolar. I'm not sure if they can be run as bipolar. If they can it would only be as (full winding) = 1/2 rated current.


8 wire motors give you all options. So they would be your best bet if you haven't deceided on which driver type you'll be using.

Hope that helps some.

Regards Terry.....

[H500]

I did not realize the wiccans mixed steppers in their brew.

[Marc]

Thanks Terry, learning some every day

Also, money wise, should I go for a unipolar or bipolar setup ?

Marc..

[H500]

If you're buying surplus, neither is inherently cheaper. If you're buying new, automation direct has a 270 in-oz bipolar motor for $40 USD.

Bipolar motors are techically superior. They can give you 40% more torque for a given motor size, but the drives are more expensive, so it's hard to generalize.

[Halfnutz]

Your safest bet is to verify they will work with the Zylotec or the HobbyCNC boards, idealy as bipolar. What that amounts to is
less than 3 amp rating
less than 5 volt rating
5 or more (6 or 8 is best) wires.
Of course its not that simple, but this is what I use to get started anyway. I would pick a controller first if I were you, then base your motors selection on its type. Also check out the new steppers. You can do well buying new. Like H500 said, check out Automation Direct. You might actually spend less there than on ebay for steppers. Servos are a different story.

[Marc]

Ooops to late, I couldn't resit, just bought 3 of those. Since my machine is fairly small (12''x19'') (cutting area of 8''x10'')and it's my first project I said to myself wtf could always sell them back to Ebay. So do you think it was a good move?

Marc..

Applied Motion Products part number 44A501711 Bipolar stepper motor. This motor is a NEMA size 23 (approx 2.25" sq x 2" deep) the shaft is 1.25 x 0.25" approx. Specs are 60 in/oz, 200 s/rev, 2.3V, 2.3A. Large quantity available.
25M002 Unit Price : $7.95

http://www.alltronics.com/images/25M002.JPG

[Halfnutz]

I dont think so, those are fine (I think) to get started with. If you need more power at some point just upgrade.

[JCOLL10164]

I have a question. How can you use a 4 wire motor (Automation Direct) with the hobbycnc drives which specify 5,6, or 7 wires?

[ger21]

I have a question. How can you use a 4 wire motor (Automation Direct) with the hobbycnc drives which specify 5,6, or 7 wires?

No. You can use the Xylotex bipolar drives though. Or the Arcsin http://www.buildyouridea.com/hardwar...in/arcsin.html
Or Embedded Aquistions bare boards. http://www.embeddedtronics.com
Or Geckos, of course.

[JCOLL10164]

ger21,

Thanks for the feedback. That's what I was thinking. Do you have a particular board to recommend. I will be interested in performance / precision over price (within reason of course)

[DieGuy]

Personally I like the Xylotex board for the money. You can run up a power supply out of 18VAC transformers that will give you about 28.5 VDC to the motors @ 3 amp. They are easy to adjust and get going. You don't need to supply a 5 vdc line as they do that internally. They do have just a small down side, they do require active cooling in the controller, i.e. a fan blowing on the heat sinks. It does supply a ~24 vdc header to plug in a fan, but I just used two 12vdc fans in series. They gave me a side benifit as they had LEDs in them and now I know at a glance when the power is on to the controller without wiring up a seperate lamp.

[JCOLL10164]

Thanks DieGuy. I'll check out the details on that board. I've seen some links to it.