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Messages - SWATH

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1
General Mach Discussion /
« on: November 15, 2013, 07:58:13 PM »
Thanks Pete,
So Mach can't do it?
It's hard for me too accept that out of all to cool and complex things that Mach3 does, it can't control the speed of your Spindle.  That just seems like such an important and fundamental aspect of a cnc control program where virtually everything is based off Spindle speed.

So do I need to remember my Spindle speed "offset" at every rpm and program in bogus S numbers to get the correct rpm?

I guess I'm also perplexed why VFDs seem to base everything on frequency instead of rpm.  I've never programmed anything based on frequency, all I care about is rpm.

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2
General Mach Discussion / Spindle calibration problems
« on: November 13, 2013, 08:45:52 PM »
I can't seem to get the spindle calibration function to work correctly.  When I start the spindle it starts fine but then when I click Autocal it immediately stops the spindle and says "Autocal terminated, spindle stopped".  Trying to do the autocal without the spindle running just asks me to start it at any speed.  I'm trying to get an accurate actual speed to commanded speed relationship but right now it is pretty far off.  For example, S200 gives me 300rpm, S1000 gives me 930rpm, S4000 gives me 5140rpm.  I've plotted the curve every 200rpm and it is not linear (especially around the base frequency of the motor at 1800rpm).

My spindle motor is an inverter duty AC motor with VFD.  I'm using a ethernet smoothstepper.  The motor also has an encoder that I have run the Z channel to the ESS to give me a 1ppr index pulse and this is working fine.  The displayed RPM in Mach is exactly the actual rpm confirmed with a laser tach.  The pulley is a 1:1 ratio and I would like to accurately go from 200rpm to 5000rpm.  Oh and the VFD frequency is controlled with a C41 card which converts the PWM to a 0-10v analog signal.

Can anyone walk me through the set up and procedure for this and tell me why it isn't working?  I've broken my brain trying to figure it out and am feeling a bit lost and burned out.

Thanks for the help.

3
SmoothStepper USB / Spindle encoder and ESS with Mach3
« on: October 04, 2013, 01:38:48 PM »
I have an ESS and 1024ppr differential encoder that has channels A, -A, B, -B, Z, -Z and I want to get it communicating with Mach.  I originally was just going to use the Z index channel and run it through the ESS but after some reading it seems that it may be possible to use the actual 1024ppr channels for better speed accuracy.  The main reason I want mach to know the RPM is so I can calibrate the spindle speed because the rpm/hz linearity is borderline acceptable but I would also like the capabilities of more accurate threading or rigid tapping (perhaps in the future).

Is this possible and how do I go about doing it?  Should I just stick with the Z channel?

5
Third party software and hardware support forums. /
« on: August 04, 2013, 09:55:20 PM »
Basically, things are working in a general sense.  The unaltered pwm signal will get me 10v on the c41 but only at minimum rpm.  Inverting the pwm signal with a not gate hex inverter chip gets me the correct signal orientation on the c41 (duty cycle goes up as rpm goes up), but the max analog output voltage is only around 6v.  I did get it up to 8v once and I'm not sure how but now it's back to 6v.

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6
Third party software and hardware support forums. /
« on: August 04, 2013, 09:42:02 PM »
I had a conversation with someone about this who knows a little about logic circuits.  He suggested that it may be the output current of the 74LS04 chip that is the problem.  The L stands for low power and outputs half of the current of a regular 7404 chip.  Does this make sense?  He Ali suggested trying a different ground between the c41 and the inverter chip.

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7
Third party software and hardware support forums. /
« on: August 04, 2013, 12:46:16 AM »
I everything seems to be basically working now.  But there is a new problem.  The original inverted pwm signal will cause the c41 output to reach 10v (when set to min rpm) but when I run the signal through the 74ls04 inverter chip the c41 will only reach 6v at max rpm.  The pot is maxed out.  I assume this is because the inverter eats too much voltage.  How can I fix this?

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8
Third party software and hardware support forums. /
« on: August 04, 2013, 12:03:21 AM »
Duh I think I see what the problem is.   The grd under the pwm input is for reference and not connected to the power grd like I thought.

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9


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10
Third party software and hardware support forums. /
« on: August 03, 2013, 11:03:39 PM »
Thanks tweaki!  I actually ended up using a 74ls04 not gate hex inverter thinking that would just be simpler.  It works!  The chip eats a little voltage though and when I add some indicator LEDs I really loose voltage, by about half.  But it does work and the pwm is going on the right direction.

I still can't get the c41 to do anything though.  There is just a constant output of 1.4v no matter what I do with the pwm input, even if I disconnect it completely.

The power is coming off the machine's breakout board and is supplied by two terminals from an on board 12v power supply that reads +V and -V and the voltage between the two measures 12.15v.  I have the +V connected to pwr and the -V connected to grd.  This is as I understand it the correct way to power it.  The -V/grd is not earth ground.

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