First of all thank you to this community for the wealth of information that has been collected here to educate those of us who came late to the party.
My question is more about feasibility than anything else. I came into (3) pk564nawa 5 phase stepper motors and their OEM driver boards second-hand and I am attempting to build a 3D printer from as many recycled parts as I can. Unfortunately I was a little impatient and bought a mega 2560 clone and a RAMPS 1.4 controller shield to drive the system, and (5) A4988 stepstick drivers to use in conjunction with the ramps. I managed to find a datasheet for the motor found at this link.
connection diagram link on right side of page
My issue is that I cannot seem to identify the wire pairs on the motor to see if it is even possible to drive it with the A4988. I have a sinking feeling that this motor is rather uncommon and the stepstick is not set up to handle a 5-phase motor.
I have been able to, with success, wire the motors through the OEM driver and an UNO to run a simple program -- 1 rev forward, 1 rev in reverse. So I know the motors are all in working order.
I have also tried to identify a common tap among the wires by measuring the resistance across pairs of wires to no avail. This may be due to the inaccuracy of my meter (walmart special) or because of the internal structure of the motor. This particular model is discontinued but by looking at Oriental Motor's current products with a .72° step, they have some kind of "pentagon configuration" for the coils...
IF it cannot be done I will either be "spec-ing" new motors or wiring straight into the mega clone and hard coding it. I'm also having issues connecting the mega to my computer through the USB so in my spare time I have been trying to learn how to flash the ATMega8u2 on the board with my UNO acting as an ISP. But that's a topic for another thread.
Any help would be greatly appreciated. I will try and answer questions to the best of my ability if you need clarification on anything. Thanks
Yes Robin. The motors and drivers came as paired units. I am also having some issues defining what a 5-phase motor is.
If its possible I'm trying to eliminate the original driver and use the stepstick drivers to save space. I can upload pics when I get home if that would help.
The original drivers are pretty large and clunky to fit into an enclosure with the rest of the electronics.
So my next question is how would I identify the wires and is there an easy way to determine the sequence for the pins. Do I just ignore the 5th lead?
I had not looked at the motor wiring as I had assumed you planned to use the "proper" drivers.
I think that is a 5-wire unipolar motor and if so it cannot be controlled with a driver designed for a bipolar 4-wire motor (AFAIK).
Some unipolar motors are actually 6-wire motors with a pair of wires connected. If you can separate those wires they can then usually be used as 4-wire motors by ignoring the separated wires. But separating them is essential.
Robin, thanks again for the input. I managed to get a hold of oriental's tech support. They gave me an operating manual for the motor which wasn't much more help than the documentation on the website.
But alas, he said he would put a request in to their engineering department in Japan for some clarification on the physical construction of the motor/what leads are connected to each coil. He will email me whatever results from that conversation.
So for now, I guess this part of the project is on hold. But I will update this when I have more info.
I do have another line of questioning though. If I were to buy new motors (building a 3d printer, so I'm more worried about accuracy than torque per say) would you recommend a unipolar or bipolar stepper motor? Does it matter how many phases? Or how many leads (4,6,8)?
That probably is a 5-phase stepper, which means it has 5 coils. Some have 10 leads while others have 5 leads, with the each winding sharing a lead with one or more others (several possibilities). Typically these motors have step sizes of 0.72 or 0.36 degrees, so they are great for precise positioning. Read more about 5-phase steppers here: Jones on Stepping Motor Types
You can drive some 5-phase motors with 2 1/2 dual H-bridge drivers like the A4988, but you have to figure out the wiring, and the step sequence is complex.
Its not a 5-wire unipolar motor, its a true 5-phase motor, 5 coils in a circle, the specs talk
about "5 phases energised" when talking about temperature rise.
It can only be driven by 5 phase bridge (or equivalently 5 half-H-bridges). The specs dont say
what the winding resistance is.
jremington - thanks for that webpage. That was the best description I've seen so far for multi-phase motors. Like I said before I'm still new to all this and I'm learning as I go.
The original drivers do work so I will probably continue down that path unless I get a favorable answer from the motor manufacturer.
You also said
jremington:
You can drive some 5-phase motors with 2 1/2 dual H-bridge drivers like the A4988, but you have to figure out the wiring, and the step sequence is complex.
Wouldn't I only need 5 half bridges like MarkT said? In theory, and someone please tell me if I am wrong but the RAMPS shield has connections for (5) A4988 stepsticks; does that mean that I could connect four phases from one motor to the first A4988 and the 5th phase of the first motor to one half of the first bridge on a second stick?
In total for (3) 5-phase motors I would need 3-3/4 A4988 stepsticks, still leaving one open to wire up the extruder motor for the print head? One other thought I had was using an UNO board in conjunction with this setup to control the direction switching aspect of this deceptively simple smelling hydra.
If that doesn't make sense to anyone I can try and draw up a picture...
Do not confuse A4988s and their equivalents with h-bridges.
An A4988 is intended for a bipolar (4-wire) stepper motor - I doubt if it can be used for anything else.
If you are considering getting other stepper motors I would strongly suggest that you get regular bipolar motors. I have tried to give an overview of the motor selection process in stepper motor basics.
As you narrow down your choice of motor you may need to take account of the associated cost of a suitable stepper driver. But there is no sense buying a motor that is not suitable just because the driver is cheap.
Again, thank you to everyone who provided input on this. I think for now I will stick with the original drivers simply to get the machine built then maybe down the road I will look into building a combined control board to bring the 3 separate drivers together. More as a learning experience than anything.
But that will be a sizeable undertaking and will probably be after I am done with the 3d printer.
I decided to use these motors because of their step accuracy so I still want to make it work with these. FYI, the driver has a built-in full step and half-step mode so I can drop it to .36°/step.
And Robin I read through your stepper motor basics. Thank you for posting that. It brought a lot of relevant information together in one place, unlike I have found on the interwebs all scattered around...
sritter09:
And Robin I read through your stepper motor basics. Thank you for posting that. It brought a lot of relevant information together in one place, unlike I have found on the interwebs all scattered around...