Stepper Motors and Control info?

[dave06]

I bought my PRT standard in 06. The stepper motors are Vexta A6497-9412KTG, the other number is SB296-2TH3.6. Unless I over looked it, I didn't find info. for this stepper on the Vexta web site. Does the SB in the second number stand for ShopBot. And this is really as PK stepper? I was looking to find out if these steppers were Bipolar or unipolar. And all the other good info. on these.
Control question: I am a person that just has to know how things work! On the PRT standard where is the Step/Direction pulse generated? Is this somthing that come's form the stepper contorl board or from the PC and control software?

[Brady Watson]

The numbers are proprietary part numbers. You will not find a reference to them on the Oriental site or by calling. They are similar to the PK296 motors, except they have low-backlash gearboxes on them (TH, not SH).

Steppers are steppers. There is no such thing as a unipolar or bipolar motor. It depends on how the stepper is driven, and the driver and number of wires used dictates if it is uni or bipolar. The PRT is run in bipolar parallel configuration. Steps are generated via SB control software and converted to waveform data that the motors understand, using the onboard processor (the brain sticking up from the mainboard).

Unfortunately, a PRT board (unless 4G version with Gecko drives) doesn't support tweaking very well. The 4G version (available as upgrade) is the one you want if you want to mess around with different motors and configurations.

-B

[dave06]

I offer many Thanks for the info. I have been reading spec. on steppers and control boards. My confusion was that some control boards list they will not run bipolar steppers. I have wired in lots of standard electric motors.
I seen the wire diagrams for these steppers and some what understand how they work. But I couldn't quite understand what these other control board spec. were talking about. (Bipolar and Unipolar steppers) I did understand them being wired in series, parallel, full winding and half winding.

One more question though! Could I use my PC with the SB control software to run a different brand stepper control board that uses the unipolar setup? I have read on this forum the setup of Mach and Geckos with other control software. But this is changing out just about everything, and using it on the PRT alpha not the PRT standard. If I was to upgrade, I would maybe like to use a different control board and steppers in the unipolar setup, and still use the SB control software.
Is this possible?


Thanks for any info on this.

[richards]

David,
I have connected Gecko G203v stepper drives and Oriental Motor PK series steppers to my PRT-Alpha control board (not for production - only for testing the electronics). Everything worked fine (except for an occassional drive fault, which means that I probably should connect a resistor between unused inputs and either ground or 5VDC depending on the 'off' state of the signal). In theory, you should be able to use any step and direction stepper driver with the PRT-Alpha controller or with the 4G controller (if you ordered it without the Gecko stepper drivers).

Before I bought my PRT-Alpha, I designed process control computers that used Oriental Motor PK268 motors and CSK unipolar drivers. They worked flawlessly for my application, but were limited to either 200 steps per shaft rotation or 400 steps per shaft rotation. I would never even consider using a 200 or 400 step motor when the Gecko gives 2,000 steps per revolution, but if you've got a bunch of old stepper drivers and you don't mind hacking a perfectly good controller board, the old fashioned stepper drivers could probably be made to work.

[dave06]

Thanks this is very good info.! My mind is in overdrive to collect and compare all this info. about hooking up a CNC system. But I don't really know anyting about the PRT-Alpha. My control board, if it means anyting is a V3.54 and it is opperating the PRT standard. I do agree and see that 200 or 400 step motors on a nice set of Gecko drives, is no well spent dollar.

Might as well spill the beans!
I have been pondering the idea of a HCNCPRO control board from W.HobbyCNC.com Not sure if anyone has tried using this board with any luck. I want in the worst way to get some hands on experence building a small desktop CNC. Somthing I could put my Dremel or maybe a small lazer on. Thought this might be the cheapest form of experence I could get. In case I burn something up. I was wanting to run it off (do I dare say) my SB control software. Because it is the one and only control system I know how to some what setup so far.

Good Idea or bad?

[bill.young]

Hey David,

Have you looked at the Developers section of the ShopBot web site? http://www.shopbottools.com/developers.htm

Bill

[richards]

David,
Bill's advice is excellent. The long learning curve that most face will be much shorter after reading that documentation.

As far as stepper motors go, I always have at least two test benches up and running so that I can test different motors, drivers, power supplies, controllers, etc. Feel free to e-mail me at miker@xmission.com (mailto:miker@xmission.com). If your question deals with something that I've already tried on one of the test benches, I might be able to save you some time (and grief).

[ted]

Hi David,

Just to add a tad more data. As Brady indicated above, the motors with funny numbers are special items that Oriental makes for us. They differ in having a low-backlash gearbox, AND they have a nicely protected and strain-relieved wiring harness. Unfortunately for experimenters, this wiring harness only brings out the coil wires for a bipolar use of the motor.

That should actually not be too problematic since most of the commodity, open-loop stepper drivers (such as the Gecko) are bipolar drivers.

Another issue for you will be that the 3.54 board which you have is probably our board that is least amenable to puttering. All the alpha boards, the Version 4g board, and all our newer PRS boards, are intended to connect to external stepper drivers -- so it is pretty straightforward to interface most any driver to them. On the 3.54, the drivers are built onto the board. Step and direction signals are present (in fact, there is a bus that is labled for all 5 channels), but it is harder to extract them since there are no specific terminals.

On the other hand, the stepper output from this board is pretty generic and you should be able to hook it up with any bipolar stepper motor rated from about 1 to 2 amps and get reasonable performance for experimenting.

We have been planning to expand our "developer kits" and specifically to add a: [Contorl Software] + [Controller Card] + [Simple-Break-out Board] that makes use of our new Controller Cards and would allow making many kinds of robotic devices. The new Controller Cards have built in USB, high pulse rates, more I/O, etc. We're also hoping to get more resources for tinkering with stepper motors on the "For Developers" page.

Until recently, we have not had much interest expressed in these things so we haven't given it a lot of attention. But since it was exactly that sort of tinkering that got ShopBot started, it remains something were enthusiastic about and would like to support.

I think the new Wiki also creates some opportunities for centralizing developer resources.

Ted Hall, ShopBot

[cjohnson]

While rearranging my shop (and PRT) this weekend, I noticed that my good ole 4g board just doesn't look right in that old pc case with wires going everywhere and all. I would like to install that 4g board in a nice new enclosure case with one of those new style higher voltage power supplies. Campbelldesigns has pictures but I don't have the time to purchase parts/weld/wire up an enclosure. Does Shopbot offer this enclosure upgrade for us 4g prt customers?

CJ