Stepper Motors

I have a friend who works at a local copier sales/repair center. When he heard I was looking into a reprap and what it can do he told me that they had several printers being set aside for disposal. They are perfectly good for parts such as grabbing the stepping motors and such. He said he would open up Sunday and I can come in and he would help me disassemble and get what I need. And in case someone asks, yes it is OK with the owner of the company, he pays them to dissasemble and dispose of the stuff anyway.

So the question is, is it worth grabbing the motors and trying them? Keep in mind these are commercial copiers/printers so they will be good quality and he looked at the Gecko drive board and said he didn't see a problem with it driving them. The question is what to look for in building a reprap. I know very little about stepping motors.

unless they are nema 17 motors I doubt they will work with reprap parts

The motor brackets for the axes will also take NEMA14 and they have the same shaft size, 5mm.

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[www.hydraraptor.blogspot.com]

Thanks... I should also point out I am not worried about the physical size. I have no parts made yet so adjusting for the bracket is not a problem. I am hoping they are NEMA 17 or larger. Guess best way to find out is to get one and spec it out.

Other stepper motors (such as NEMA23 or non NEMA motors) will work if you're using them for a repstrap rather than a reprap. Getting gears/belts/etc is either something you'll need to scavenge from the printer itself, or buy/manufacture to suit.

Big thing to keep in mind is the numbers of wires on them.

If it has an odd number of wires, it'll most likely have one that is common to all the coils. The electronics we tend to use cannot drive these sorts of motors. I have no idea if the Gecko driver can, but I think it's got the same limitation.

If it has an even number of wires (4/6/8) then it most likely can be made to work.

4 Wires should work as is.

6 wires will have two extra wires (3 wires per coil). The middle wire in each coil is a common (for that coil only) and you should be able to just ignore it.

8 wires have 4 coils. It takes a bit more work but you can join the 2 of the coils on each side together to form a single coil.

Note: Some motors are actually DC motors with an encoder shaft on them, which can be driven to emulate a stepper. These might be able to be used for something (eg: extruder), but not all sets of electronics can drive a DC motor.

Printer steppers usually have a pulley already attached to it. I don't know how they attach the pulleys, but its near impossible to get it off. It won't be the same pitch or tooth amount that Mendel calls for, but you can work around that, although you'll need to source the same pitch belts. The stepper shaft length will vary in different printers; too short of a shaft won't work with a Mendel. Also, you'll need to look up the datasheet for the steppers you find to make sure they will have enough holding torque. The wiki has a lot of good info on steppers.

I had the same idea as you since I had a few dot matrix printers in the junkbox, but they were 7.8 degree steps and were each different from one another. I ended up buying my 4 steppers from alltronics and it came out to ~$50 shipped. Although I don't think they stock the stepper I purchased anymore.

@Cefiar

Thanks. I had read up on the number of wires (I am actually digging around the site some). The Gecko does not work with odd wired motors and from what they say are considered older motors. I am hoping that these being newer style printers they may have newer motors as well.

I need to look up the difference in a restrap and a reprap.....

@xchristopherx

Thanks for the info... I have a 2-ton press that will either pull the pulley off or separate the shaft from the motor

Thanks for the tip on alltronics. I am in Arespace/Defense so I was thinking of stepping motors in the $50 each range....

The pulleys are more than likely interference fit by thermal expansion then cooled on the shaft. Get a small blow torch on the pulley and they will come off quite easily without damage or too much force.

ablainey Wrote:
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> The pulleys are more than likely interference fit
> by thermal expansion then cooled on the shaft. Get
> a small blow torch on the pulley and they will
> come off quite easily without damage or too much
> force.


That's an option. Most items you can place in an oven for about 2-3 minutes at 250 degrees and the parts will fall off. But I am sure the heat would not do good on any plastic or other materials in the motor. I just find it easier to place things in the press, they are usually separated in a few seconds.

If you use a blow torch on the shaft while its still installed in a stepper could you risk ruining the magnets?

Even if you know for sure that a printer doesnt contain a usable stepper motor its still worth pulling apart to salvage the DC motors, stainless steel shafts, belts, opto switches, glass plates and gear wheels. All of these parts come in very handy for odd projects, reprap related or otherwise.

This is the result of pulling apart about 5+ printers.

The larger stepper motors look like they should be powerful enough. Use the best on the X an Y axes, because they move the most. The extruder also needs power, but it moves the plastic slowly and so several stages of gear reduction will make a weaker stepper have enough torque to push the plastic through the tip. It looks like you have plenty of gears to pick from.

I would leave the drive pulleys on and try to find matching cogged belts. Nothing will hold on the shaft like the original pulley/gear.

Looks like you have at least one repstrap there!

Mike

@Capo

Nice stash.... hopefully I can come away with that much. Will depend on how long my friend wants to stay and tear down printers. But I forgot about the rods, should be able to use them as well.

Oh and make sure you put down an old sheet of some sort before starting work. Even with the toner toner cartridge removed you will still find areas that have damp components that will stain both your clothes and your carpet if your not careful. Best of luck!

Thanks... I have no carpet in my house.... Allergies.. Only wood and concrete for me...

I ordered a NEMA 14 size stepper motor from Polulu by mistake because they didn't specify what it was. It didn't fit my parts so I just put it aside and ordered the 17s because it wasn't worth the shipping to return it.

I looked at this page for the Lin Engineering Stepping motors from Alltronics. The part numbers listed must have changed. Looking at the site I found these motors and wanted to make sure I am comparing the same motors.As I have stated in another post I have ordered a Isaac and looking to get parts in. So looks like the build is on now, no turning back.

Those are the exact same motors I found. They seem to be the most feasible for Mendel at the moment, at least from Alltronics. I'm still waiting to hear back if they're compatible with Mendel though... Looking at the specs, it looks like they'll work. What's nice about this one in particular is they have nearly four times the required torque! At least you have enough torque, hehe. Looking around Alltronics, I found [www.alltronics.com] which looks like it could work as well. The only problem with that one is that it doesn't come with a connector, and it's a little on the low end of torque (albeit above the minimum for Mendel, 19.4 oz-in required, 21.0 oz-in provided).

Edited 2 time(s). Last edit at 11/17/2010 11:43PM by An Original Name.

yea, I think I may order these unless someone sees a major problem. I haven't looked at the gecko specs yet, but it may not matter if it has a connector, I may have to replace it anyway.... I would rather have more torque, just incase I want to do replaceable heads later.