[CNC] Has anyone any experience with 5 phase steppers?

[Erx]

Rex,
Stepper motors are brushless, so the use energized poles to move the rotor. I would suggest that you read a document on steppers called "Jones on Steppers" available all over the web and at the Univ of Iowa site also. The number of poles in a stepper determines the resolution that you can gain by lessening the movement of the rotor for each energized pole. Once you have read the article on steppers and still have questions do not hesitate to ask and we will get you turned the right was pretty easilly.
Bob

Thanks for the reference. I'll spend some time with that. I have some small knowledge of steppers, and a book called "Easy Step'n", but had not run across any 5 phase steppers before, and was unaware of their existence. I bought these motors a year ago, and found little info then, however, after posting this I googled and found more info, much of it referring to a motor with 5 wires.

This motor is a VEXTA Model PH599-A, 5-Phase, .72"/step, DC 1.15A, 3.25ohm. Below those specs: SX8 03215 ORIENTAL MOTOR CO., LTD, Made in Japan. Picture to follow

Rex

 

[Erx]

Here is the Jones. and a print.

http://homepage.cs.uiowa.edu/~jones/step/types.html

"Billy G" )

Oh boy, now you've gone and done it! I'll be up all night...

Thanks,
Rex

 

[Erx]

As far as software goes, I believe mach3 would be able to handle the math. I'm not sure about controllers though, which i believe is the more pertinent question. The software just figures out steps per table movement, the controller needs to relay that to the 5 poles. I'm not up on the capabilities of controllers.

You're right, I guess that really is my question. I wasn't aware enough of the operation of Mach3 (or any machine control software) to know if they commonly dealt with differing degrees/step, but it seems reasonable that they could. Now my attention gets shifted to a controller. I'm comfortable with electronics wiring, circuit boards, soldering, but it's been years since I programmed something so I might want to find a commercial product.

Thanks,
Rex

 

[Erx]

snip
See here. http://www.stepperworld.com/Tutorials/pgUnipolarTutorial.htm

The other main type (apart from three phase steppers - not normally seen in commercial applications) is the Bipolar (AKA two phase, sine-cosine, or 4 wire stepper motor). These need to commutated by connecting each wire to positive or negative in a specific sequence. This is normally done with a circuit called an H-bridge. Bipolars offer the advantage of more torque in a given size, and the ability to be microstepped. Microstepping offers the ability to position the motor in between detents (as long as power is on).

Unipolars can not be microstepped easily if at all. They are also larger for a given torque because only 1/4 of the available copper is used at any time. There is a way to get 1.4 times the torque, but the motor will step in between detents and power must be retained to maintain position. The big advantage to unipolars is the ease of commutation.

My company designs and builds custom brushless DC and stepper motors for space applications and I design the motion controllers for these radiation filled environments. Stepper motor drivers and applications are my area of expertese.

If it has 5 sets of windings (ten wires) that's a horse of a different color. It could actually be a 5 phase motor (VERY uncommon) or two unipolar motors sharing one rotor. These can be used individually for reliability by redundancy or connected in parallel or series for higher voltage or higher current applications (usually seen only with Biploar motors)

John

Well, I have ten wires, 5 sets of windings. Might be why they were so cheap...
This motor is a VEXTA Model PH599-A, 5-Phase, .72"/step, DC 1.15A, 3.25ohm. Below those specs: SX8 03215 ORIENTAL MOTOR CO., LTD, Made in Japan.
John, thanks for the reference, I'm going to be busy reading for a while. I wish I had a fraction of your knowledge...

I should take a moment to thank everyone that posted, I'm a bit overwhelmed at the response, you folks are amazing!!

Thanks,
Rex

 

[Erx]

If there are 10 wires coming out, take a voltmeter and try to figure out which wires are connected to which. If you have 5 pairs of wires connected, then yep, you probably have a 5 phase motor, something I didn't even know existed...

In that case, I think you are going to have a problem finding an off the shelf controller to handle that. If you are handy with electronics, you could probably put a controller together. Its a bit of work, but doable.

If the motor has 5 wires coming out, it's probably not a 5 phase motor. More likely it is a regular unipolar stepper motor with the center taps tied together. Recall that in a unipolar motor you typically tie the center tap to ground, so it doesn't matter that they are tied together. I don't think you could run a motor of that type with a bipolar driver.

Yes, I have 5 pairs of connected wires, 10 wires total. So far, this isn't sounding good if I need specialty electronics. Yes, I could design the board and solder the parts and, after a few months and multiple frustrations I might program a controller - but I doubt if I could make an effective controller as a first project. If a predesigned special purpose controller chip exists, I could probably fry a couple of those...

Thanks for the info,
Rex

 

[Erx]

A unipolar motor does require a different driver then a bi-polar. Both are readilly available on the net and from Spark Fun and other hobby vendors. The key to steppers is pulse sequence and speed. Remember that steppers lose a lot of torque at higher RPM which is counter intuitive when working with electric motors. The stepper motors strongest point is the ability to move a certain number of steps and hold that position. Most specs on steppers that say 1054 inch pounds or whatever are giving you the holding torque of a fully energized motor and NOT the actual torque the motor will develop. Gecko makes a very good drop in controller with great tech support and the pres of that co. answers his own phone when you call. They have probably the best cust service I have ever encountered in an electronic/electrical supplier. Geck also has a site at Yahoo groups.com that will assist with resolution of issues prior to calling tech support. The Gecko co. owns that list and monitors it as well. I use steppers on my CNC plasma table and my automated Z axis and have a plan in the works right now to add a stepper drive to my 3-n-1 machine for long travels and slow repeatable surface finishes.
Bob

I've heard favorable things about Gecko, don't know why I didn't ask them this question - well, actually, I do know why - I had to sound out my thoughts on you guys first so I would know what I didn't know!

Thanks for the Yahoo groups suggestion, that'll be one more group to read. Hardly get any sleep as it is, oh well, keeps me off the streets.

Thanks,
Rex

 

[Erx]

Good point Bob. The advertised value for torque is usually the powered holding torque. All motors have a torque speed curve where available torque falls off as some function of speed (ideally linearly, but other effects enter in to make it non-linear).

For a stepper motor, the torque falls to zero and the motor fails to run "in sync" at the speed where torque generated by the windings are unable to overcome the detent torque + hysteresis + viscous damping + friction. All of the above losses are speed independant except for viscous friction. That's why strange things happen when the motor loses sync and it jumps around, runs, runs backwards (when the commutation sequence comes back around).

The torque constant (Kt) is usually also specified: where torque is motor current times Kt. This is only true with a stepper motor at the beginning of a step however.

Do you have a picture of this motor?

John

John, here's a couple of shots. Diameter is 3 3/8", length of motor enclosure is 3 3/4", altogether much beefier than all the other steppers I've collected.

My motors are either obsolete or special purpose. The Oriental Motor website search engine offers no hits for "5 phase", "PH599", and multiple unhelpful hits for "599", although the .72" motors are probably all 5 phase devices. There is a pdf for a PK599 motor of the correct frame size and step but it has 5 connections (pins) and 1.4 amps rating. On this motor, the windings are connected "in series" and each connection leads to the internal join of 2 windings.

The pertinent webpage is:
http://www.orientalmotor.com/products/pdfs/2012-2013/A/usa_st_pk_motor_only_overview.pdf




Thanks for all your time,
Rex

 

[Erx]

i wonder if the extra 2 wires may be a temp sensor/thermal limit like some dc motors have?
steve

Good thought Steve, but this motor really is a 10 wire, 5 phase, 5 pairs of windings type of motor.

Thanks for your suggestion, in a better world it very well could have been a conventional 4 winding stepper with a position sensor.)

Rex

 

[Erx]

Well, I have ten wires, 5 sets of windings. Might be why they were so cheap...
This motor is a VEXTA Model PH599-A, 5-Phase, .72"/step, DC 1.15A, 3.25ohm. Below those specs: SX8 03215 ORIENTAL MOTOR CO., LTD, Made in Japan.
John, thanks for the reference, I'm going to be busy reading for a while. I wish I had a fraction of your knowledge...

I should take a moment to thank everyone that posted, I'm a bit overwhelmed at the response, you folks are amazing!!

Thanks,
Rex

Just checked out the Stepperworld site, alas it is no more. A cached copy says he is too busy with his other business iFarady.com which seems to manufacture stylii for iPads and other capacitive touch screens. He suggests that people check out the StepGenie IC, which "... generates the sequence of signals required to produce the stepping movement of a stepper motor."

Thanks,
Rex

 

[xalky]

See if you can get in touch with the people at gecko. The make very reliable and fairly inexpensive( for what they are), controllers. CNCzone.com has a huge knowledge base for these types of things, and i think gecko drives has thier own sub-forum which gets answered regularly by the gecko techs.