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Messages - maddios

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1
SmoothStepper USB / Re: How to use closed loop spindle rpm with SS
« on: October 23, 2011, 12:55:55 AM »
Hey Cork, sorry for the super long delay, I took a long break from my cnc machine and just recently got back into it and actually started cutting stuff.

Not sure if you still need settings, but mine work with a G540 geckodrive, which outputs 0-10V.

I don't remember exactly why I chose certain settings but I do remember that the G540 had certain pwm requirements as well as the SS.

in the SS config dialog I have my spindle set to 64khz, spindle set to PWM at a 2000Hz rate.
in the Ports & Pins spindle screen I have my use spindle motor output and pwm control checked, base freq is at 50 and min pwm is 0.

From here I think all I had to do is tune the pulley settings until the pwm curve output by mach matched what my spindle did. Therein lies the problem, I'm not using a VFD so the rpm mapping is near impossible as a DC motor doesn't have linear rpm to voltage curves. So I've been trying to get closed loop spindle control but so far has been unable to get it to work. I've yet to try the latest beta SS drivers available though.

Not sure if we can get any more insight from the SS developers as to what's missing here of it it's even possible with the current SS drivers.

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SmoothStepper USB / Re: How to use closed loop spindle rpm with SS
« on: November 21, 2010, 07:26:28 PM »
So, is there no way?

Is this just a limitation of the SS driver or does the mach3 closed loop controller not work right now?

My expectation as to how it should work is that when I select type in S3000 and my rpm sensor reads say 3060 or something it'll adjust PWM output to 3000/3060*(previous PWM) applying the PID coefficient to smooth out any oscillation that this math will cause.

3
SmoothStepper USB / Re: How to use closed loop spindle rpm with SS
« on: October 27, 2010, 11:32:00 AM »
I'm actually using a DC motor controller KBMM-125, it's a 16A 90VDC controller. There's really no adjustment on this thing other than max current output, accel/decel time and min/max speeds.

4
SmoothStepper USB / Re: How to use closed loop spindle rpm with SS
« on: October 26, 2010, 03:38:11 PM »
I'd still like to get my Mach3 to operate closed loop though, as regardless of whether or not I have a linear setup, the motor still needs to have higher PWM when load is applied to increase power. When I'm back up and running I'll try again

5
SmoothStepper USB / Re: How to use closed loop spindle rpm with SS
« on: October 24, 2010, 08:15:49 PM »
Alright so seems like my G540 was bad. I just tested my SS with a scope and the pwm output is perfect, however looks like the g540 has degraded further and now no-longer outputs anything. I'm feeding it a known good voltage with a 9v battery and seeing zero output from pin 8.

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SmoothStepper USB / Re: How to use closed loop spindle rpm with SS
« on: October 22, 2010, 11:28:46 AM »
Hm, yes it does, thanks, I will try that and maybe it'll help with some of my issues. Mach manual is very vague when it describes what to put in those fields, took me forever to realize that the spindle max is the 100% side of the pwm requested.

7
SmoothStepper USB / Re: How to use closed loop spindle rpm with SS
« on: October 22, 2010, 02:04:16 AM »
If you have the sensor on the spindle make sure you do not have anything but a '1' in for any of the pulley ratio boxes.

Hmm, a 1? I put a .4, what does this number mean? I'll try that tomorrow night.

8
SmoothStepper USB / Re: How to use closed loop spindle rpm with SS
« on: October 21, 2010, 10:05:16 PM »
haha, yeah, i'm like 99% sure i can have configuration issues:) There are so many variables to account for in setting up mach 3 that it's almost a guarantee that some issue will come up. I'm going to work on trying to resolve the issue this weekend, test out the output PWM from SS, compare it to the scaling out of G540, check noise on the control lines to the KBMM, etc.

The tach sensor is on the spindle itself, motor is connected to the spindle via a toothed belt via a 0.4 reduction. I also verified the index rpm was correct with a laser tach, it was within a few %.

I'm going to go through my configuration this weekend too, to make sure i didn't miss anything, and i can try to post some screenshots of the config screens.

Just as a side note, the closed loop spindle control does or doesn't work with SS? In your setup, if it does work, if you put a load on the motor, how long does it take Mach 3 to respond and bring the speed back up?

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SmoothStepper USB / Re: How to use closed loop spindle rpm with SS
« on: October 21, 2010, 01:06:20 PM »
Guess I should give a little more background here, I know for a fact that my G540 outputs its 0-10v vfd signal non linearly, as in when I request s2000 I get 2.4v and when I do s1000 i get 1.6 which is WAY off, and then when I do s3000 I get 3.8v.

I'm going to put a scope on my setup and try to determine if my PWM is possibly incorrect coming out of the SS, or maybe I have excessive noise feeding back from the KBMM-125.

My question was really a more theoretical, in a situation like this, true closed loop control would be able to adjust out all of this error and dial in the correct speed via the PID algorithm, but I've till now been unable to get the adjustment to happen at all.

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SmoothStepper USB / Re: How to use closed loop spindle rpm with SS
« on: October 21, 2010, 01:01:54 PM »
Yeah, well, they're pretty linear, but not perfectly, and that's true, my error could be anywhere in the system, as i'm using an SS -> G540 -> KBMM-125 (motor speed control)  -> motor.

I can control motor rpm within mach 3 with the S word, but the motor rpm is never what I actually want, it's correct at around 1800 rpm, but then at s3000 actual rpm is like 6k and at s1000 actual is like 340 so there seems to be a pretty epic curve. I'm using an ac/dc motor with a max rpm of 30k, i believe it was removed from a vacuum cleaner it doesn't have permanent magnets, but rather a coil.

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