[shopbuilt]

My current setup uses nema 34 8n•m closed loop stepper motors with 60v power supply 1605 ball screws. With this I get 280ipm rapids but I feel there should be more there and I'm guessing the issue is the high rpm causing the torque to drop off. I'm thinking of two options to get faster movements:
1. 1610 ball screws. Pretty simple way to get more speed at a lower stepper rpm.
2. Belt drive the stepper and over drive the screw so the stepper is in a more ideal rpm range but still driving the screw faster.
I realize that both option will result in a reduction is resolution but is there a clear benefit to either option or a better option all together?

[joeavaerage]

Hi,
all stepper motors lose torque the faster they go....thats just plain physics and you can't get around it.

The most important specification that determines how fast the torque degrades is inductance, the lower the inductance the better the stepper will perform at speed.
What is the inductance of your steppers?

It is common for 34 size steppers of moderate to high torque such as yours to have high inductance and therefore the torque degrades badly at speed. Funnily enough
many (low inductance) 23/24 size steppers, say 5Nm or so, will actually outperform your 34 size steppers at speed.

23/24 size 1mh- 2mH, 1 mH preferred and reject anything over 2mH
34 size 2mH-4mH, 2mH preferred and reject anything over 4mH

The classic way to overcome sluggardly performance at speed is to increase the drive voltage, you should be running your steppers at least 80VDC, but 100VDC or more would be better.

The real solution is to ditch the steppers and get servos......they eat steppers alive. I use 750W Delta B2 series (160,000 count per rev encoder) and they so wildly outperform steppers its not funny.

https://www.fasttobuy.com/flange-80m...er_p28084.html

I have them direct connected to my 32mm x 5mm pitch ballscrews. At 3000rpm, the servos rated speed, the machine does 15m/min, but I can push them to 5000rpm for 25m/min, and still have accelerations
of better than 0.25g (without use of overload, 0.75g with overload).

Typically a servo has a modest continuous torque rating, the 750W Deltas are 2.4Nm continuous for example, but their temporary overload it three times that or 7.1Nm. Its this overload that means that servos seem to perform
much better than the specs would suggest.

Craig

[peteeng]

Hi Shop - 280ipm is 7112mm/min. Divide that by the pitch and you have the motor RPM ie 1422rpm. This is very good for N34 motors. So simplest is to go with 10mm pitch but even better would be to go with servos as they can run at 3000rpm or greater. But you will have to check the 16mm screws don't become unstable (whip and whirl). How long are they? Peter

[dazp1976]

Ditch the steppers and get AC servos.

[cncmakers001]

Better change to AC servo motor and AC servo drivers.