Bipolar Driver, Great Deal?

[FLUTE HEAD]

Hello All, I ordered three of these bipolar stepper drivers. Just wondering if anyone has heard of or had any experience with this one or one similar in a kit form. If so, what size motors have you ran with it? Any drawbacks? The drivers are in kit form, take about an hour and a half to assemble, and cost 20.00 each. bipolar driver 5-30vdc

[High Seas]

Hey - looks/sounds like a good deal - waiting to hear your review when built and up and running. What motors are you going to run with them?
Jiim

[cbcnc]

Flute,

That does look like a good deal.
It says it will drive bipolar motors to 50v @ 6a.
I think that you will need a breakout board, though, to manage all the LPT pins.
Check out pminmo's open source designs for one. It's in the links section.
Let us know how it works out.

Chris

[FLUTE HEAD]

I'll Let You Guys Know How It Works. I Ordered Some Of Dan Mauch's 600 Oz.in Bipolar Motors.

[fyffe555]

Just in case it's not obvious the kit drivers like the one you've listed here are all discrete component drivers, that is they have no smarts and they're *not* chopper drivers. That means if you use more than the Motor rated voltage, which you will, you have to do current limiting with power resistors in line with the motor to avoid blowing something. 50v @ 6A means some big resistors. Be careful calculating what size resistors you need for your new and costly motors.

As an aside chopper drivers can and usually do drive the same motor with more effective power and speed than a non chopper driver.

[FLUTE HEAD]

Fyffe555, Thanks For The Input, And No It Wasn't Obvious To Me. What Do You Mean By No Smarts? And Do You Have A Calculation For What Size Resistors? Thanks, Matt

ALSO, SHOULD THIS DRIVER BE COMPATABLE WITH MOST PROGRAMS? I'LL BE TRYING EMC

[ger21]

Looks like full step only, as well. Balsaman has a program for calculating resistor size. Not sure if it's posted here anywhere or not?

[fyffe555]

Matt,

'no smarts' - a slang way to say the driver kit has no logic to measure current and 'chop' the power to maintain a given current for a motor. Stepper motors work best on several times their rated voltage where the power is controlled by limiting the current. Non chopper drives need a current limiting resistor inline with the motor to limit the current. This uses power which is prduced as heat from the limiting resistor. Chopper drives have a variety of logic inbuilt in specifically designed chips (ic's) to do that, and provide other functions like microstepping.

If the driver takes two inputs, Step and direction, where the step and direction switches High and low ( 5v+ and <0.8v+) then that's pretty much the standard and most generic Cam software (turbocnc, Mach2, EMC ) will run them.

To calculate the resistors needed you need to know the rated Volts and Amps for your motor, and the voltage you intend running them at. You also need to know how you intend to wire them to measure the coil resistance of the motor.

Balsaman put up a utility program to calculate the resistors needed called Stepcalc (stepper calc?) which would do it all for you and I can't recommend it enough if you're new to this. I don't have a link but you could PM Balsaman or perhaps someone will help you out here.

To work it out manually the calc is for all intents and purposes Ohms Law, where V=I*R so for steppers;

Vpowersupply = Vdrop + ( I * Rmotor) + (I * Rlimit)

Where;

Vpowersupply = voltage of the power supply you intend to use. For Steppers its seems to be best to run them at 10-25 * face plate Voltage.

Vdrop = the voltage drop across the power transistors used in the driver. If you're not sure look at the datasheet for the device or guess at 2v to be on the safe side.

I = current you want the motors to run at.

Rmotor = measured resistance of the motor coil in the configuration you intend runnig it in.

Rlimit = the resistance of the current limiting resistor you need to find.

This will give you the Ohms necessary for a resistor for each coil of each motor.

To work out the power rating (watts) needed you need to work out the Voltage across the resistor and the current ('I' from above), and the power rating would be V * I in watts.

Note you need identical resistors on each motor, one in series with each of the two motor coils. Expect the resistors to get hot...

[FLUTE HEAD]

HEY THANKS 555,
Alot of what you said sounds familiar, even for a rooky like me. Thanks for clarifying

[tpworks]

look here page 3 for link to steppercalc

http://cnczone.com/forums/showthread.php?t=3822

Ipurchased those same drivers only from here

http://electronickits.com/kit/complete/motor/ck1406.htm

[FLUTE HEAD]

hey TP, how did you like your drives? Were you satisfied with just full stepp operation. What kind of accuracy are you getting with full stepp? I built three and haven't used them yet. Still putting together the whole set-up.

[tpworks]

I haven't used them yet either, as I'm still working on the machine I am going to use them on. I have put them together though and the motors that I am using have a gear head so I dont think the full step will be a problem.