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Author Topic: Spindle Index problem.  (Read 25745 times)

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Offline SimonD

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Spindle Index problem.
« on: May 04, 2008, 04:55:46 AM »
I am trying to use a CNC4PC C3 index card into a C11G BOB. I am wired into pin15 for the index, I have tried pin10 and it made no difference.

My spindle disc is 125mm diameter. The spindle should run at 3200 rpm.

The slot width calc gives...

0.0088 x 0.0012 x 3200 x 125 = 4.224mm

The slot in the disc is 6.3mm wide.

Mach3 sees the index pulse when I turn the spindle by hand, I have tried both active low on and off.

Mach3 sees the speed upto about 200 rpm but anything above that and it still reads somewhere between 200 and 250 rpm. it never goes any higher.

What am I doing wrong?

Thanks
Simon

Offline Hood

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Re: Spindle Index problem.
« Reply #1 on: May 04, 2008, 05:00:39 AM »
Simon, few things you could try
Try setting the Index Debounce up a bit
Try making the slot a bit wider (10mm is what I use)
 Try using 2 slots, one wider than the other then setting it up to use Timing in ports and pins, Inputs rather than the Index.
Hood

Offline SimonD

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Re: Spindle Index problem.
« Reply #2 on: May 04, 2008, 05:07:37 AM »
Thanks, I'll give them a try...
Simon
Re: Spindle Index problem.
« Reply #3 on: May 04, 2008, 05:27:36 AM »
Hood

Is there anything to be gained by having more slots I.E. more accuracy

Phil_H
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline SimonD

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Re: Spindle Index problem.
« Reply #4 on: May 04, 2008, 05:41:50 AM »
I seem to be able to get Mach3 to read just about any rpm value I want for the same spindle speed...

I set the debounce level down from 100 to 10 and it looked promising so I ran the spindle calibration... it seemed to run well but afterwards the machine only runs at full pelt or nothing. It doesn't seem to be taking into account any acceleration or deceleration values. Afterwards I tried an S200 command and it tried to accelerate the spindle so fast it blew the main circuit breaker!

The index debounce was set to 100.
If I set it to 200 then it reports one value, if I set it to 400 then it reports a different rpm even when the spindle is running at the same speed?

The "calibrate spindle" dialog has a bit about number of slots and states that the value should be 0 for 1 slot but mine is reading 1, could this be causing the problem? how do I set this value?

Thanks
Simon

Offline SimonD

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Re: Spindle Index problem.
« Reply #5 on: May 04, 2008, 09:01:42 AM »
I have played about with the "index debounce" value... I am reluctant to change the size of the slot right now, presumably if it can't see a slot reliably even at slow speeds, making the slot bigger isn't going to help? Presumably I only need to make the slot bigger if it isn't reliable at fast speeds.

Anyhow here is the strange results I got...

Run the spindle at a requested speed of 500rpm.

Index Debounce        Indicated RPM
10                          1928
20                          963
40                          481
80                          275
160                        148
320                        77
640                        39
1280                       flips between 0 and 40


Surely the indicated RPM shouldn't be roughly proportional to the Index debounce value should it?

Thanks
Simon
Re: Spindle Index problem.
« Reply #6 on: May 04, 2008, 09:12:56 AM »
Simon,
You may want to keep the Debounce setting in between 1 and 10. Setting it too high will cause it to miss many of the pulses, resulting in reported speeds slower than actual.
RC

Offline SimonD

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Re: Spindle Index problem.
« Reply #7 on: May 04, 2008, 09:17:53 AM »
Ah.. ok thanks, I will try that and report back...
The default install set the index debounce to 100 so I assumed it needed to be quite high. it also set the input debounce to 500.

Thanks
Simon
Re: Spindle Index problem.
« Reply #8 on: May 04, 2008, 09:48:10 AM »
One other thing, if the input was active low, it would be ON the entire time that the slot is not at the sensor, quite a long time per rev. Active high, the input is on only while the slot window is open resulting in a much shorter pulse. Mine works fine with 0 debounce.
Seems so anyway, please correct me if I'm wrong,
RC

Offline SimonD

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Re: Spindle Index problem.
« Reply #9 on: May 04, 2008, 10:13:16 AM »
The sensor wants to send an output when it is blocked so I have switched the active low setting so that the LED on the Mach3 screen lights when the gap lines up with the sensor.

if I set the debounce levels low e.g. 0-5 the reading is about 1930-1940 rpm when a S500 is requested.
I have no real way of measuring the actual speed so I turned it down to S50 and it reported about 102 rpm I then counted 50 turns and it took about 30 seconds so the reading looks right at that speed.

So I commanded an S100 and got an indicated 595 rpm!

So I thought I would try some other speeds...

S50      102 rpm
S100    595 rpm
S200    Stopped
S110    275 rpm
S120    Stopped
S300    377 rpm
S350    621 rpm
S400    702 rpm
S500    792 rpm
S600    923 rpm
S700    1060 rpm
S800    1202 rpm

At the last one I took the voltage applied to the inverter. It read 2.12v with a reference voltage at 10.22v so it is about 1/5 full speed which is 663 rpm

So the S commands don't seem to be outputting a proportional voltage and the index reading is erratic.

How do I reset everything and start again?