Messages

1

General Mach Discussion / Re: Understanding spindle control in MACH3

« on: October 11, 2016, 01:29:55 PM »

I tried now to use S7000 M3 instead of M03 S7000. It's the same: only the second S7000 command reduces the speed.
If I type S7000 in MDI and start my G-Code it is also the same behavior.
If I type S7000 M3 in the MDI spindle also starts up at high speed (10.800). If I enter S7000 the again, the speed drops to about 7000. Pressing ESC after that stops the spindle.
If I run my G-Code then, it works as desired. But only for one cycle. If I let it run until the end and then start it again, it starts up at high speed and drops down at the second S7000 command.

I think there is something weird happening after spindle stop or at spindle startup. And it is no difference if I start the spindle via MDI, via GUI button or via G-Code. Always the first start is at high speed. And why 10800 rpm? That isn't either MAX nor MIN.
What I also noticed, if I change speed in a move command like "G00 Z50.0 S10000" it does not wait for reaching the speed. It increases the speed but then moves immediately, not waiting until reaching the desired speed.

2

General Mach Discussion / Re: Understanding spindle control in MACH3

« on: October 09, 2016, 10:20:40 AM »

Now I had some delay further investigating the issue.
I configured the pulley now exactly like the inverter. I set minimum to 6.000 rpm and maximum to 18000 rpm. The PWM to analog converter does exactly what it should. If I set spindle speed to 6000 I get 0V, if I set it to 18000 I get 10V, a value of 7000 gives 0.8V and 10.000 gives 3.4V.

But I found a hardware issue at voltages below 0.8V, my Benezean Breakout board begins to trigger the spindle stop signal then. So if I set the speed to 6100 the motor stops. I can live with that.

But the wrong startup speed is a bad thing. It seems a MACH3 issue, all the voltages are correlating to the given speeds below. So the hardware seems ok to me.

I wrote a small GCODE for demonstration which I run in single step mode. After the hash sign I wrote the spindle speed I get


G90               # off
G91.1             # off
M03 S7000         # 10920 rpm !!!
M03 S7000         #  7080 rpm
G00 Z50.0 S7000   #  7080 rpm
G00 Z50.0 S10000  # 10200 rpm
G00 Z50.0 S7000   #  7080 rpm
M05               # off
M30               # off


You see that at the first start the spindel speed is much to high. After the second speed setting all runs as intended. What about the first start? Why goes it wrong?
I can help me with that double M03 command, but it's not nice.

The same happens if you set the speed via GUI. You type 7000 to the spindle speed field, press spindle start and it runs up to 10920 rpm. Enter 7001 and it slows down to 7080. (the delta of 80 rpm is ok for me, it's a bit of error of the PWM to voltage converter on the breakout board or the ADC in the inverter, I think.

3

General Mach Discussion / Re: Understanding spindle control in MACH3

« on: October 05, 2016, 04:01:01 AM »

Ok, I forgot to mention that I have a PWM to analog converter. I also checked it's function with an oscilloscope.

It is really so that MACH3 generates PWM pulses that does not fit the onscreen value at the first spindle on press. It then adjusts correctly at the first speed change, e.g. pressing the plus key at the spindle control.

The second question is how do I tell MACH3 which PWM value correlated to which speed?

4

General Mach Discussion / Understanding spindle control in MACH3

« on: October 04, 2016, 02:38:48 PM »

Hi,

I have difficulties understanding what happens to my spindle speed, using the manual control.
First the problem:
When program starts, the spindle is off, the spindle speed is displayed as 5.999 and S-OV is also 5.999. This is exactly my pulley minimum. When I press the spindle on button the spindle speeds up to 10.800 (display on the Inverter), but displays 5.999 in Mach3.
If press the "Spindle +" key the spindle decelerates (!) to 6.780 which is near the minimum speed of 6.000 setup in the inverter. MACH3 shows 6.599.
Pressing "spindle +" again the spindle accelerates to 7.560, MACH3 shows 7.199.
Pressing "spindle -" returns to 6.780 / 6.599.
Pressing "spindle -" again stops the spindle, displaying 5.999 in MACH3

So there are two questions.

• Why does MACH3 always accelerates to 10.800 rpm when pressing the "Spindle start" button? Shouldn't it start with the speed displayed on screen?
• How can I setup the right speed translation. My wanted speed range is 6.000 .. 18.000 rpm.

Now my setup:

The spindle is controlled via PWM via Smoothstepper.
Inverter is configured such as a voltage of 0V is the minimum speed of 6.000 rpm and 10V is the maximum speed of 18.000 rpm. I veryfied this using a regulated power supply to the voltage input. Stopping the spindle is achieved by stopping the PWM pulse.

Pulley is set to 5999 min and 18000 max.
Spindle Motor Configuration is set as follows:
steps/mm = 1
speed = 100002 (I don't know why I did this, but it seems to have no effect)
acceleration = 491520
G's = 50,123243
Step pulse = 2
Dir puls = 2
mode is set to PWM with 50Hz in Smoothstepper configuration