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Mini CNC motor drivers
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Mini CNC motor drivers

by iworkinpixels on Mon Nov 15, 2010 12:56 pm

Hey guys, my name's Tony... I'm a web designer from Missouri...

I got an ARDX a few weeks ago and have been having fun playing with motors and LEDs... now it's time to build something cool.

I've wanted a Makerbot/RepRap for a while but can't afford one as of yet, so I'm starting out building an easy, low cost CNC mill to get my feet wet building and learning about CNC systems before attempting to build my own 3D printer...

I'm working off of this design:
http://www.instructables.com/id/Easy-to ... g-Machine/

I've got the frame up and a few of the rails cut, and now it's time to start bolting motors to the thing. So, a couple of questions:

1: I'm going to try to use some NEMA 17 motors like the instructables build suggests, so does anyone know of a really cheap place to source them? I found several on eBay that was like $20 for 4 of them, but then there were a bunch that were $40 for just one of them, so I got to thinking that maybe the 4 pack was cheap crap from China that was going to break in a week... so a good source of cheap but good motors would be appreciated.

2: I need to drive them... and since I already have an Arduino, can I go Computer > Arduino w/ motor shield > Steppers, or do I need to buy/build a whole stepper driver board? I've never messed with steppers before, so this will be a learning experience. If I have to build or buy, what kinds of things do I need to look for in a kit or design?

Thanks!

iworkinpixels
 
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Location: Forest Hills, NY

Re: Mini CNC motor drivers

by adafruit_support_bill on Mon Nov 15, 2010 1:49 pm

For a 3 axis machine you will need three steppers which is more than the MotorShield can do. This thread has a good alternative: http://forums.adafruit.com/viewtopic.php?f=31&t=15835&p=81580&hilit=pololu+stepper#p81580

As for cheap vs. good, you should be able to find decent quality motors for ~$15 each from reputable dealers. You might do better (or worse!) on eBay.

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Re: Mini CNC motor drivers

by iworkinpixels on Mon Nov 15, 2010 1:56 pm

Thanks for the reply!

So... when shopping for motors, what do I need to look for to separate the good motors from the bad ones?

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Posts: 32
Joined: Mon Nov 15, 2010 12:43 pm
Location: Forest Hills, NY

Re: Mini CNC motor drivers

by adafruit_support_bill on Mon Nov 15, 2010 2:27 pm

I haven't run across a lot of truely bad ones. Most of those were from from Chinese companies I had never heard of. In my experience, the US and Japanese branded ones are all pretty good - regardless of where they are manufactured.

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Re: Mini CNC motor drivers

by iworkinpixels on Mon Nov 15, 2010 2:45 pm

Awesome. Just pulled the trigger on these:

http://cgi.ebay.com/3-STEPPER-MOTORS-3- ... 0123671182

And I should be good to go once they arrive.

iworkinpixels
 
Posts: 32
Joined: Mon Nov 15, 2010 12:43 pm
Location: Forest Hills, NY

Re: Mini CNC motor drivers

by iworkinpixels on Thu Nov 18, 2010 4:07 pm

Holy balls! The motors that I ordered off of eBay came in today... and they said "NEMA 17" on them so I figured that referred to the size, and they'd be the same size as the ones I saw in the McWire video...

Not so much. These buggers are HUOOJ!

motor.jpg
Very large motors
motor.jpg (42.17 KiB) Viewed 2037 times


So now I'm thinking I'm going to have to completely redesign the device because
A: these things are really heavy. That's not going to do nice things for my ghetto x and y stages.
and
B: I'm pretty sure they have enough torque to rip the machine apart.


Also, they said they were coming with the chips to build a controller for them, but what I got was a bunch of pcbs which not only have those chips, but also some caps and other stuff on them... what am I looking at here (sorry I am at work and can't open it up yet to detail what's in there)? Is this the controller board and I just need to send it logic signals?

IMAG0101.jpg
The chip and its cap friends...
IMAG0101.jpg (58.92 KiB) Viewed 2037 times

iworkinpixels
 
Posts: 32
Joined: Mon Nov 15, 2010 12:43 pm
Location: Forest Hills, NY

Re: Mini CNC motor drivers

by adafruit_support_bill on Thu Nov 18, 2010 4:18 pm

Those are quite a bit larger than nema 17s. The ebay link you posted says nema 23.

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Re: Mini CNC motor drivers

by iworkinpixels on Thu Nov 18, 2010 4:22 pm

You're right... I was looking at several of this guy's motors and he had a set of NEMA 17s, but I guess I mixed these up with those because the size wasn't in the title.

At any rate, now I've got what I've got, and I need to use it to build my CNC... just, you know... a much bigger one now. :)

iworkinpixels
 
Posts: 32
Joined: Mon Nov 15, 2010 12:43 pm
Location: Forest Hills, NY

Re: Mini CNC motor drivers

by iworkinpixels on Thu Nov 18, 2010 8:01 pm

Ok, I'm home now and was able to remove one of the chips from its casing...

IMAG0102.jpg
IMAG0102.jpg (47.42 KiB) Viewed 2022 times


We've got the chip, a 6 wire connector for the motor, a 10 wire connector for something else, and 3 caps on the front.

IMAG0103.jpg
IMAG0103.jpg (67.04 KiB) Viewed 2022 times


And on the back, some surface mount goodies.

What am I looking at here? Is this a controller board and all I have to do is have a sanguino controlling these boards and an extruder board and I'm good?

Also, shouldn't there also be a separate power connector on this for the big beefy motors?

iworkinpixels
 
Posts: 32
Joined: Mon Nov 15, 2010 12:43 pm
Location: Forest Hills, NY

Re: Mini CNC motor drivers

by adafruit_support_bill on Fri Nov 19, 2010 6:45 am

I think that big chip is your controller. There was a link to the spec sheet on your ebay page. If you can figure out the pinout of that connector on top you can probably use it as is. Looks like a one-sided board, so that shouldn't be too hard.

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Re: Mini CNC motor drivers

by iworkinpixels on Fri Nov 19, 2010 9:00 am

Yeah it's the controller... here's the schematic that came with it...

IMAG0104.jpg
IMAG0104.jpg (57.1 KiB) Viewed 1997 times


But someone over at the CNCZone forums told me it wasn't a microstepping controller, so it's all kinds of useless for a 3D Printing application.

In that case... anybody know if RepRap electronics are going to be capable of driving these?

iworkinpixels
 
Posts: 32
Joined: Mon Nov 15, 2010 12:43 pm
Location: Forest Hills, NY

Please be positive and constructive with your questions and comments.