What size stepper motor do I-need.

**JAZZCNC** · 09-06-2014

I'll save you a lot of headache and just say use 3Nm motors run at 65-70Vdc on 75-80vdc drives and you won't have any problems cutting anything.

Cutting speeds will depend on many factors like spindle power and tool material but 4500-5000mm/min wouldn't be out the way with 2.2Kw spindle using carbide tooling.

**IanParkin** · 10-06-2014

Can you suggest a supplier of a kit of parts to do as you have described Jazz? for a 4 axis machine?

**Neale** · 10-06-2014

I'm planning to re-use a set of Zapp SY60 3nm motors, 68V linear power supply and analogue drivers which should do for starters, then, and I'll see how it goes. Can always add another motor if needed.
This whole design process is interesting: we are urged to study, analyse, carefully consider. I used the spreadsheet to get better insight into motor sizing but the answer, in practice, comes down to "SY23 because SY17 are too small, SY34 are too high inductance, and you might as well go for 3nm as they cost barely any more than the lower power motors in that frame size." Power supply sizing is similar.
Ian - you could look at the Zapp web site for a kit. The price (at least when I bought) is the same as buying the individual parts but at least someone has identified a bunch of bits that play well together.

**IanParkin** · 10-06-2014

I have the much reviled ebay 4 axis kit all on one board which i bought to get me going

having said all that its been absolutely fine and reliable but now i'm using it more I thought i would get a proper set up with individual drivers so in the event of problems i can switch a faulty one out

I was looking at cnc4you's site but his drivers are only up to 50v with a 36 v power supply
I'll have a look at zapps site

Ian

**Clive S** · 10-06-2014

Originally Posted by IanParkin

I was looking at cnc4you's site but his drivers are only up to 50v with a 36 v power supply
Ian

Cnc4you is the best place to buy the steppers 3.1nm low inductance that I know of. But not the drivers Ebay is your friend for them like this one :- Leadshine AM882 Digital Stepper Motor Drive 80VDC 0 1A 8 2A Protect Function | eBay although I think there is a newer model you might find a better price as well. ..Clive

**IanParkin** · 10-06-2014

looking at zapps site I cant see any kits of parts but if i put together
4 dm856 drivers 4 nema 23 3 nm motors and one plc6x BOB and a 68v 6amp power supply
its £632 ish

Cnc4you's kit of parts is 356 plus vat 427 ish thats this kit ...Nema23 Stepper Motor Kit 4Nm x 4 Axis

will I notice any major difference with either of those over my cheapy ebay special ?

**JAZZCNC** · 10-06-2014

Don't go with the kits has they tend to be under spec'd on the PSU or have lower spec drives etc. You don't really save anything buying kits anyway if you shop around and to be honest if you build your own PSU you'll save more money.

Ian Check your PM's.

**tzar** · 17-12-2014

Originally Posted by irving2008

The calculations are contained in a Excel spreadsheet in the attached zip file

Thank you very much for this! But I have question.
For example I have 2 screws for X axis and 2 motors as a result. How I should make calculations in this case? I just need to double "Holding Torque", "Detent Torque" and "Rotor Inertia"?

**CNC Visions** · 05-05-2015

Thank you very much for a very informative explanation on motor selection.
I'm upgrading an older machine that had two motors driving X axis gantry. How do I calculate the motor size with two motors on the same axis? Is it a simple as dividing by 2?
Gecko recommends a 40% increase in motor size from base calculations, do you agree?
Thanks again
Mike

**Boyan Silyavski** · 07-05-2015

Originally Posted by CNC Visions

Thank you very much for a very informative explanation on motor selection.
I'm upgrading an older machine that had two motors driving X axis gantry. How do I calculate the motor size with two motors on the same axis? Is it a simple as dividing by 2?
Gecko recommends a 40% increase in motor size from base calculations, do you agree?
Thanks again
Mike

Not so simple. First you need to know the moving mass. Then the desired speed and acceleration. Then you decide the motors and the ratios. Then you check if your BOB can cope with that. Then you check what your resolution will be. Some back and forth between all that and a final decision. At least that's my logic.