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Cnc router motor upgrade opinions
« on: March 02, 2017, 02:34:04 PM »
I am looking to upgrade my motors on my router. Does anyone use the hybrid stepper motors with encoders? I like the clearpath motors but there a bit out of my budget. I have nema 23 425oz/in motors without aa data sheet. Does anyone have any suggestions for motor upgades? Good couplers to use on motor directly mounted to shaft of ballscrews in all axis. I have 5mm pitch.
Re: Cnc router motor upgrade opinions
« Reply #1 on: March 02, 2017, 05:21:57 PM »
What rrason for an upgrade? What is your power supply voltage? What is the voltage rating of the drivers? The motors may not be your weak link.
Re: Cnc router motor upgrade opinions
« Reply #2 on: March 02, 2017, 05:36:42 PM »
48v power supply 12 amp, drivers are 24-50v. My machine has worked great for over a year. No possition loss is good, more torque at higher rpm is better. I have a prety heavy gantry. My pc is windows 10 64 bit so I might swith to ethernet ss also. The hybrids are supposed to have smoother positioning less heat more efficient so as the manufacturers claim there performance is not comparable to a normal stepper.
Re: Cnc router motor upgrade opinions
« Reply #3 on: March 02, 2017, 10:33:42 PM »
My homebuilt mill has a 67 volt linear power supply at 20 amps powering 80 volt drives for 960 ozin Nema 34 steppers driving 5mm x 20mm ball screws. I have it set for 3000mm/min but it runs fine at 4500mm/min no missed steps. 1500 rpm from the motors is pretty decent.
Re: Cnc router motor upgrade opinions
« Reply #4 on: March 03, 2017, 01:14:56 AM »
Hi,
I think I go with garyhlucas on this one. 425Oz/in works out to 2.2 ft lb or 3 Nm, with 5mm pitch 20mm dia screws to
give a stall thrust of 4000N or 400kg force, isn't that enuf?

The trick of course is to maintain that at speed which with steppers is all but impossible.

I use small Vexta 5 phase steppers of about 90Oz in thru 10:1 low backlash planetary gearboxes. The output torque, at low speed,
is 880Oz in or about 6Nm, tons of grunt but fairly slow. I run them at 2400 rpm with the gearbox output shaft at 240 rpm for rapids
of 1200mm/min with 5mm pitch screws. Its only a small machine so I don't usually fall asleep when doing rapids.

What impresses me is that 5 phase steppers are considerably smoother running than two phase steppers and the loss of torque at speed
is less pronounced.

I have recently bought another stepper for an A axis, a Vexta 5phase 34 size, 804Oz in direct. It supposed to run at 2.8A but I have it running
on a 1.4A drive at 3000rpm no sweat!

I'm using Vexta drivers and they produce about 150V peak, so its probably no wonder that they speed along OK....
If you want speed consider 5 phase steppers, they're rare and expensive likewise good high voltage drivers. Probably little to pick and
choose between them and genuine servos but they are QUICK.

Craig
My wife left with my best friend...
     and I miss him!
Re: Cnc router motor upgrade opinions
« Reply #5 on: March 03, 2017, 05:30:19 AM »
Thanks for your replies, I appreciate all the helpfull insight.

Offline ger21

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Re: Cnc router motor upgrade opinions
« Reply #6 on: March 04, 2017, 07:38:31 AM »
Most 425oz motors have very high inductance, and won't run very fast on 48V.
You'd get much better performance from them with good quality digital drives,  like Leadshine EM806's, and running them at 72V. They probably be 50% faster, smoother running, and cooler.
Gerry

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Re: Cnc router motor upgrade opinions
« Reply #7 on: March 04, 2017, 10:40:54 AM »
Yes the motor inductance is the key factor in speed. When I built my machine I bought the lowest inductance motors I could find. Mine came from Primopal. Also have the leadshine digital drives.
Re: Cnc router motor upgrade opinions
« Reply #8 on: March 04, 2017, 01:49:32 PM »
Ger your a huge help, I will look into that.
Re: Cnc router motor upgrade opinions
« Reply #9 on: March 04, 2017, 02:17:43 PM »
Those drivers look nice Ger. When i take the plunge I'll post a follow up. Thanks again!