Stepper stall

[Hamiltonwoodcraft]

Hi, I’m trying to find a solution for our 4896 router. Specifically the Y axis, it runs on a 25mm ball screw with a 5mm pitch. The stepper is a ~640oz 5.5amp. It has a G540 running at 48v. I understand the stepper is limited by the 3.5amp so I’m not getting the 640oz more around 410oz.
Is there any possible way of achieving higher RPM for this motor with the current setup? The stepper turns at 367rpm giving me roughly 80ipm being direct drive. Anything beyond this and it loses steps or stalls completely.
I’ll attach the drawing spec for the stepper.
Will upgrading this stepper with a lower Mh give me the ability to run it higher Rpm? Also is it possible to use a Teknic Clearpath sdsk on a g540?
Replacing the screw is my main thought but thought I’d see if there’s any other options. I believe I have asked this before but cannot find my post.
Thanks

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[joeavaerage]

Hi,
the problem is that the inductance of the stepper is moderately high, 4mH, not the highest out there but a long long way from the best.

Inductance is a good measure of how badly the torque will fall as speed increases. To my knowledge there is no torque/speed data published for your motor but based on similar motors
where such data is published I would expect about 10% of rated holding torque at 1000rpm. Thus your stepper would have about 64oz.in at 1000rpm, and given that you are
throttling it by reduced current about 41oz.in

A 640 oz.in motor of 1mH could be expected to have 40%-45% or 256oz.in to 288oz.in at 1000rpm.

The classic way to overcome, or rather mitigate, there is no overcome, reduction in torque is to apply a higher voltage. The current crop of available and reliable stepper drivers capable of 5.5A and more
are rated at 80VDC.

The G540 is a nice unit and is reliable....but its insufficient for your steppers. Either replace it with three individual drives of 80VDC and an 80VDC power supply and program the drive to exploit
all 5.5A of the motors rating, OR, buy some decent low inductance stepper motors, OR, both.

If looking for steppers, in 23/24 size look for 1mH to 2mH, 1mH preferred and reject anything over 2mH.

Of the two strategies I think the first, namely replacing the 50VDC, 5.3A G540 (nice but just too damn small), is the best option. You may get around to replacing the steppers at a later date
but getting some decent voltage and current from separate drivers is going to perk up your existing steppers bigtime.

Craig

[joeavaerage]

Hi,

Also is it possible to use a Teknic Clearpath sdsk on a g540?

You don't need a G540 to run a Clearpath servo, just a cheap breakout board will do. Make no mistake Clearpath's are AC SERVOS and they eat STEPPERS for breakfast.

I personally don't like Clearpath's, they are too expensive for their low power output, they have low resolution encoders and woefully insufficient IO, not withstanding they
are excellent quality and backup.

I use Delta servos (Taiwanese brand made in China) and others use DMM (Canadian made in China) as good quality servos with high resolution encoders good backup and set-up/tuning software
at very fair prices. My 750W Delta B2 (160,000 count per rev) costs ($435) less than a 400W (actually 397W) Clearpath (800 count per rev) at $517. That's nearly twice the power for LESS.

If you stump up for good servos (Delta, DMM, and grudgingly Clearpath) you can kiss your machine speed problems goodbye. Assuming you choose and buy the correct servos
for the job you'll have to slow them down.......not worry about speeding them up.

Craig

[boydage]

Increasing the pitch of your screws from 5mm is to good advantages too for sure. Depending on your tolerances also not too expensive unless you are going for ground screws.

Sent from my SM-N970F using Tapatalk

[dazp1976]

Hi, I’m trying to find a solution for our 4896 router.
Thanks

These 640 motors are 6.3A and 2.2mh (in parallel wiring config). https://www.automationtechnologiesinc.com/products-page/nema-34/kl34h280-45-8a

Now, I have updated my nema 34's driver to a DM860T from stepperonline that can run on 110vdc (80 vac). I was using 60vdc to run before but have gone up to 80vdc with new driver because of speed stalling. (mine is 4.2mh 1080oz).
I would NEVER go back to running a nema 34 on less than 80vdc and am upping it again to 90vdc soon based on the speed increase I got.

So, you put the above motors (even your existing will prob see good performance), connected to DM860T drivers, run them off 90vdc-100vdc.
You WILL see a huge speed jump!.



OR..... Buy Delta type AC servos!.