Printer steppers dead, looking at replacements from Digikey

[ipodman1991]

Hey, my stepper motors from from cnc, that i took from an old printer are dead. im looking to get some new ones, and seeing as Digikey sells them, i could just get them with my next order. digikey has two companies, Epson, and Portescap. they have nothing on the epson motors, so im now looking exclusively at the Portescap ones.

heres the listings of them:
http://tinyurl.com/3dgedl

would any of these seem like suitables alternatives for a cnc machine?

[HayTay]

ipodman1991,

All of those Digi-Key motors appear to be too small, 25.5 oz-in or less and 100 steps/rev. For the 25.5 oz-in motors it looks like Digi-Key is going to gouge you for $40.62 US. Most of the CNC tables you see people building here on CNCzone have started out equipped with 100 oz-in motors or larger and 200 steps/rev.

Keling Inc. is offering:

11A: NEMA 23 BIPOLAR STEPPER MOTOR 156 oz-in, ¼” dual shaft with a flat, Specification KL23H251-24-08B Price: $29 ( in stock)

These motors can be run in multiple configurations [unipolar, bipolar (series), and bipolar (parallel)] depending on what type of controller board you have. Note that if these motors are set up for unipolar operation the holding torque rating is approx. 110 oz-in.

You may want to consider replacing your current dead steppers with motors pulled from old HP LaserJet II/III/IID/IID printers. Those motors are 100 oz-in, 200 steps/rev, unipolar, inexpensive and relatively easy to acquire. As a matter of fact, I've been using them on my JGRO designed CNC table for over a year with satisfactory results. So are a lot of other builders.

The bottom line is, don't limit yourself to the motors you found at Digi-Key, look around for motors that are better and give you more bang for your buck.

[ipodman1991]

Ok, thanks. i was just wondering about them because it would be more conveinent for me. ill definetly (sp?) look at the link you sent.

[HayTay]

Have you got any pictures of your machine and the motors that have 'died'? Maybe what you need is a NEMA 8, NEMA 11, or NEMA 17 sized motor if you've got a CNC router with a smaller footprint and smaller motor mounts.

Do you remember what 'old printer' you pulled the motors from?

[ipodman1991]

Originally Posted by HayTay Have you got any pictures of your machine and the motors that have 'died'? Maybe what you need is a NEMA 8, NEMA 11, or NEMA 17 sized motor if you've got a CNC router with a smaller footprint and smaller motor mounts. Do you remember what 'old printer' you pulled the motors from?

actually, i asked my electrician friend to help me pick unipolar steppers for a cnc machine. he found three and said "these oughta do". guess not. no stickers on them, nothing. i could ask him for specs.

the cnc has a platform of 6"x6".

[Rance]

Originally Posted by ipodman1991 ...the cnc has a platform of 6"x6".

ipod,

Now that's a horse of a different color. I'll go ahead and stick my head out here...

While the info. that HayTay is most often the case, however if you have such a small platform, then a 25oz motor might just be enough for you. You can try to get free replacements for your motors from HP inkjet printers or from 5.25" floppy drives. The ones on the floppys even come with driver boards. As for getting them for free, try www.freecycle.org in your area (even in Canada). Or put up a small note on a bulletin board where you work. I like the floppy drive route since they come with drivers but used inkjet printers can be had for free all day long. Oh, and yes, digikey seems to be gouging. Hope this helps.

[ipodman1991]

i hope you understand what i mean by 6"x6"

that actual footprint of the whole machine is about 12"x6". 6"x6" is what the dremel actually mills.

[Rance]

Originally Posted by ipodman1991 i hope you understand what i mean by 6"x6". The actual footprint of the whole machine is about 12"x6". 6"x6" is what the dremel actually mills.

Yes. We're on the same page.

[ipodman1991]

Originally Posted by Rance Yes. We're on the same page.

ok just checking. you seemed a bit surprised about the size. i think its worth mentioning that its use is milling pcbs about 90% of the time. thats why its so small.

ill look around for some motors from floppy drives. seems liek the ones i had before may have been overkill

[HayTay]

Yes, I'm with you. With that small of a footprint and what you're milling you're not going to need the larger stepper motor(s).

Here's a link to stepper motors at Alltronics. See if you see something similar to what you're currently using. Prices for the motors start at $1.49 US.

Here's a NEMA 17 stepper motor at EOL Surplus that's only $8.50 US each. It doesn't state the holding-torque rating. (picture)
Astrosyn QH4-4276-01, $8.50, 40 Available. Stepper motor, 200 Steps/Rev., 2.3v 0.7A, NEMA 17 frame size, approximately 1-5/8" square x 1-5/16" long, 3/16" x 1/2" shaft has an easily removed cog belt gear on it. 4 Wire, Has removable mounting plate with rubber washers. New.

NEMA Size........Frame Size (Metric)........Frame Size (Imperial)
.....08.......................20mm...........................0.8"
.....11.......................28mm...........................1.1"
.....17.......................43mm...........................1.7"
.....23.......................58mm...........................2.3"
.....34.......................86mm...........................3.4"

Make sure you get the correct type, unipolar or bipolar, for your drive controller. You don't want to kill anything else off. Speaking of which, are you sure it's the motor(s) that have failed and not the controller?

[ipodman1991]

yup, its the motors that are dead. but ill poke around at the board to see if something is shorted or something.

edit: the board is fine. no shorts, correct parts are used. its the motors. in case you want to know, im using the same board engadget used:
http://www.electronics-lab.com/projects/pc/008/

edit 2: i measured my motors, and they seem to be about 60mmx60mmx75mm. i guess they were nema 23's.

[HayTay]

ipodman,

Yep, that would make 'em NEMA 23s.

Also, per your link to the controller board your using:

Originally Posted by Electronics Lab "This controller is designed to control (3) three unipolar stepper motors at up to 35V@1.25A continuous."

NEMA is an acronym for National Electrical Manufacturers Association. They set standards for motors, connectors and other electrical items. One of their standards is for motor mounting flanges as you have already gathered.

Here's a Minebea Astrosyn 23LM-K255-01 unipolar, 8-wire, stepper motor from Alltronics. From what I can gather the motor is NEMA size 23, 1.8 degrees/step (200 steps/rev), and rated at 1 amp. All that for $7.95 US each plus shipping/handling/tax.

Given the additional information you provided, I would steer clear of those stepper motors you were contemplating from Digi-Key. They all appear to be 2-hole, flange mount stepper motors with various steps/rev from 20-100. And they're a lot more expensive, to boot.


IHTH,