Picking out a Driver bd-newbie ???

[lemonyx]

Phil

I went to the Keling site http://www.cnczone.com/forums/showpo...85&postcount=8 and found this motor 4: NEMA 34 HIGH TORQUE STEPPER MOTOR 637 oz-in, ½” shaft with a flat, 80 mm KL34H80-45-4A (Single Shaft) Specification Price: $89 ( in stock) again looking thru your site you don't have a driver bd, bipolar, that goes to 4A will the Unipolar one's work? Sorry for the stupid ??

[vacpress]

i think running a modern square-frame stepper motor such as that with a unipolar board would result in less power output than a bipolar chopper board. the bipolar boards deliver more even amounts of current at different speed, the unipolar boards rely on huge 'ballast resistors' to maintain a costant current drain. This results in heat, and for big motors like these I think you may spend as much on these big resistors as you would on a good controller board.

The reason the unipolar boards seem to offer so much more power at a lower cost is that the electronics are alot simpler. The bipolar operation and constant current control require more inteligent control than a simple logic based unipolar board.

Most people would recomend geckos or similar for motors that size. www.geckodrive.com

xylotex, another popular driver are a bit small for that. What are you trying to move with these motors? That motor is big enough to move quite a big load. You may save alot of money by reconsidering your needs and looking at smaller steppers and appropriate driver boards.

People here seem to be using anything from 20-400oz/in motors with their zylotex boards and getting from 20-200IPM depending on their configurations. 1 gecko costs about $150. 3 xylotex boards cost about $150.

With geckos, and all their loyal customers, id imagine you get what you pay for. I will know soon.

Geckos max out at 7amps, i think. xylotex at 3.5 or 2.5... not positive.

Hope that helps

[ger21]

Not all unipolar boards use ballast resistors, Vac. The HobbyCNC is a chopper drive, and can give comparable performance to a Xylotex, and in some cases better performance because it can use higher voltages.

As for the original question, that motor appears to be a 4 wire motor, which can NOT be run with a unipolar drive.

[lemonyx]

Thank you guy's for the help. The reason for the "big" motors as I don't want to under power myself. The material will be 99% acrylic and 1% alum.

I was gonna to use these on the first machine, then use it to build the second and better one and just take the parts with me - thinking less $$ in the long run.

Thank you jerry

[ger21]

Geckos are probably the best choice for those motors.

[vacpress]

gerry, oh, that is true. i suppose i right away began thinking about the cheap $15 driver board kits... i get the feeling unipolar chopper drives are sort of rare? dont most stepper motors produce less power in unipolar mode however you drive them?

lemonyx - that is what i am doing also.. i have got the first machine 75% done... and have been trying to decide on all the little bits that are left.. motors, and linear actuator for a 24" axis..

but anyways. i was also planning on matching some geckos with those kellinginc motors. they seem like a good match..

let us know if you try this out. i will not know for a week or 2.. waiting for geckos to get motors...

[lemonyx]

press

Thanks, but it'll be sometime when I get started. I like to do all the info gathering and spec finding before I start. On the motors, I want the biggest that I can "use" and not be under powered but also have to remember the good ole pocket book

I went looking thru the specs again and found this motor which is both uni and bipolar. NEMA 34 HIGH TORQUE STEPPER MOTOR 637 oz-in, 1/2” shaft with a flat, 80 mm KL34H80-45-8A http://www.kelinginc.net/KL34H280_45_8B.pdf so maybe I can use Phil's discrete or L297 driver bd's.

[vacpress]

yeah. i was looking at those also. i will likely purchase one of the 990oz/in ($99.00) motors this week and give it a shot with the xylotex and homebrew unipolar drivers ive got.. the kellinginc is local to me, and only about 5 miles from where i go to work every day. i am waiting for gecko drives to arrive, and when they do i will know more. it seems to me of the motors on the site, the $49 NEMA23 450oz/in(or whatever) and the NEMA34 990oz/in for $99 seem to offer the best values... it costs alot more to goto the larger motors.. $20 more, or 20% for a 170oz/in gain in power.. i suppose it depends on the application. I would imagine these large motors in a router would produce very quick and powerfull movement. I am thinking the extra power these things would generate on my fairly small system will equal greater accuracy as lost steps wont be a problem.. More like the thing having enouch power to wrench itself apart could be a problem..

[sdantonio]

In the event that you go with the picsteps you will need something like this (I just started another thread asking if this flash unit is sufficient for programming the PIC's.

Steven

Will this do what I want it to do?