View Full Version : How to spec drivers and a power supply

21-02-2016, 08:33 AM
Hi All

I'v been merrily using my CNC plasma cutter that I built a couple of years ago with some very useful input from you. and for that I'm very grateful.
The plasma build was based on a kit from Zapp that works very well.

I've now been given three small steppers

The details are

Model Number

Phase voltage (V)

Phase current (A)

Phase resistance (Ω)

Phase inductance (mH)

Detent torque (mNm)


So what sort of drivers should use and how do I work it out?
What power supply do I use and how do I work it out?

Would I "get away" with a 12v power supply? Does it just need to be 3x the 0.28A so approx 1A? ..... or am I barking mad?
My forte is the mechanical side, electronics\electrics are still very much a steep learning curve for me, but having the reasons explained should help others in the future too as well as allowing me stop asking very similar questions.

I'm sure someone will ask "what's it for"? So far I've no idea - they are not powerful so probably something that will control pyrography iron, a laser for paper cutting or maybe even a 3d printer print head?

I hope this helps and look forward to hearing form you soon ;-)


21-02-2016, 11:04 AM
With nema 14 an Arduino Mega2560 Ramps 1.4 and $2 drivers would be more than enough have a look at something like this, available on aliexpress for around 20 power supply 12v either PC ATX with slight modification or 12v 300w to alloow enough power for laser diode hot end etc. Have a look at RepRap Wiki for details on this sort of build.
1pcs Mega 2560 R3 + 1pcs RAMPS 1.4 Controller + 5pcs A4988 Stepper Driver Module +1pcs 12864 controller for 3D Printer kit

23-02-2016, 07:43 AM
Thanks Lucan07
That looks just to be just what I need. Much appreciated.
Now to decide what to build..... :-)

23-02-2016, 08:06 AM
They are quite small for a 3d printer so probably best suited to laser engraving which with 2w diode costing around 60-70 on aliexpress would cut card, paper, cloth, thin leather and rubber etc and engrave but not on clear plastics etc.

27-02-2016, 05:42 PM
Hi Lucan07
I like the idea of a laser. I have no experience of these machines so please bear with me. :-0
If I wanted to cut 3mm birch ply I believe I would need something like a 30W+ laser. (Feel free to correct me. )
Would the machine need bigger motors, drivers etc? .. and if so why? (To improve my understanding and not to challenge you) Or would I get away with it?
When shopping for a laser is there anything I need to be aware of?
Getting excited at the thought of a new machine! I even know where it will go! :-)
Thanks so much for your valuable help.

27-02-2016, 09:52 PM
Yes a 30w Co2 laser would be about right for 3mm ply, you could get away driving with that set up if bearings etc smooth.
Shopping for lasers probably means a cheap chinese laser and power supply etc, costwise building it yourself would be more expensive than buying a k40 40w c02 3020 system from ebay slightly over 320.
Buying tubes generally means the chinese on Aliexpress want courier to prove arrived broken before claim accepted, couriers are not going to wait for you to open PLY box then cardboard and remove packaging so its a gamble on it actually arriving in one piece. Cheap chinese lasers vary in quality and do not last last very long if run at anything over 60% power.

I had a friend who purchased the cheap ebay K40 model and the tube lasted only 2 hours, but with a claim and persistence quoting UK trading full refund obtained for him and they were responsible for collection of the faulty item within 7 days which they failed to do and have still made no attempt to do so, now his property. Only buying through Ebay and paying with paypal saved him getting ripped off claiming via credit card companies etc possible but a real pain with eBay was simple peobably many such claims they were on the ball anyway.

If you needed larger area than 3020 I would still go that route, play with it on arrival and make sure all ok with unit and then use parts or modify to get what you needed from your build, ensure cooling up to scratch running hot radically shiortens life of tubes but a 2ltr bottle of water frozen dropped in a bucket would keep you going for a few hours.

27-02-2016, 10:36 PM
Cheers Lucan07
I'll take your advice on that. Which is great as I now need to buy the machine you mentioned above and build my New machine. Result! :-)
Excellent food for thought.
Much appreciated.