Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: tmccub840840@gmail.com on March 02, 2017, 02:34:04 PM
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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.
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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.
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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.
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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.
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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
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Thanks for your replies, I appreciate all the helpfull insight.
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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.
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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.
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Ger your a huge help, I will look into that.
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Those drivers look nice Ger. When i take the plunge I'll post a follow up. Thanks again!
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Hi All,
have just been looking at the Leadshine website, all sorts of goodies...
I have not had the chance to play with any of their gear and ask what is your opinion re quality/reliability?
Those DM series drivers look like the 'bees knees', doesn't specify the peak output voltage but guess its rather more than 80V,
really good for high speed ops. The Vexta drivers I use also have 230VAC input and I got a surprise when I put my scope on
the output and found 150V peak output. Must stress the stepper insulation like hell but I've been giving them what-o for a few
years without fault and they're not new when I got them.
Given that high voltage is the simplest expedient to overcoming inductance induced delay I would have thought manufacturers would
be pushing for higher voltage specs, vacuum impregnation and that sort of thing, the same as they do for servos.
Craig