# Spindle speed, lathe



## Transformer (Dec 3, 2014)

On going CNC project.  I have installed a 3 phase motor and a VFD.  I can control the motor speed and thus the spindle speed by turning the dial on the VFD but I want to know the actual speed on the spindle so I can eventually do threading.  

I have a proximity sensor that I can rig up so it sends a signal every revolution of the spindle, but where do I send that signal so I can get a readout of actual RPM of the spindle?

I have a controller that has a VFD input for +10, analog in, and ground.  But I think this is for controlling the speed of the motor on some proportional basis and not for receiving the signal from the proximity sensor which would allow actual spindle speed to appear in Mach3.

At this point I am not interested in using Mach3 to control spindle speed. (That would be nice but I am already in over my head.)  I just want to get an accurate readout of spindle speed.  

All suggestions appreciated.

(Leeson motor, VFD is a GS2 from Automation Direct, controller is from Camtronics, lathe is a Grizzly G0602)


Dennis


----------



## awander (Dec 3, 2014)

You feed the signal from the prox sensor to the Index input in Mach3.


----------



## jumps4 (Dec 7, 2014)

Hello Dennis
in mach3 turn threading can only be done on a breakout board using a parallel port as far as I know. a uc100 usb will not work and I'm not sure any other usb or ethernet cards thread.
mach3 needs to be an older version the latest version does not work ( I'll try to see what version I'm running and send it to you )
pins 10,11,12,13 and 15 are input pins on the breakout board, use what ever one your not using for homing and limit swiches that is left.  and on the configuration input screen set that breakout board pin number as the "index"
you can only use one pulse per revolution.
here is a good mach3 pdf to help you out (  http://www.machsupport.com/wp-content/uploads/2013/02/Mach3_Threading.pdf   )
threading works best a low speed in mach3 usually not above 150
other people have other results but mach3 turn has never worked correctly for threading and it has required the writing of mach4 to try to resolve the problems. but dont rush out and buy mach4 i'm not sure they have it working yet either . I read their yahoo group daily and see nothing about threading on the lathe yet.
the longer the thread is and the greater the pitch the greater the chance of mach3 making a mistake, at this point i'm having good results at 3 inches of threads at 8 threads per inch turning 100 rpm.
shield all your input wiring, ground the shield only on one end at the controller.
once you have all this working then I would try connecting it to your pfd
trying to do them both at the same time may cause you more problems resolving issues.
hope that helps
Steve


----------



## Transformer (Dec 11, 2014)

Steve, great and intimidating info there. 

 At this point I am still trying to get a read out of spindle speed in Mach3.  As suggested earlier I have activated the index input and set it to pin 13 but I get no speed readings.  I have played around with the active low and emulated setting but get no reading.  When I put a value in S (which should have no effect as I am controlling spindle speed via the VFD) and click on spindle at the bottom of the screen, the S True DRO counts down from this number to zero. On the diagnostics screen the Index button is lit, but it does not flash.

Is there a way to test if a signal is actually getting through on pin 13?

The sensor I am using is a an inductive proximity sensor NPN.  I need some new approaches to try.

Dennis


----------



## stupoty (Dec 11, 2014)

Hello,

a lot of digital multimeters have a hz input that will display frequency from a sensor like that, handy if you need to test.

or you could check the switching action turning the spindle by hand and checking the sensor output.

Stuart


----------



## Transformer (Dec 11, 2014)

Stuart:   When you say turning the spindle by hand and checking the sensor output do you mean checking to see if the index button flashes on the diagnostics screen?  Thanks.

Dennis


----------



## jumps4 (Dec 16, 2014)

hi Dennis
sorry for taking so long to reply I was Ill
if you do not see the index light flashing on the diagnostics screen as you turn the spindle try going to config, ports and pins, input signals, index, make sure it is set to port 1 pin 13 and then try selecting "active low"
steve


----------



## Transformer (Dec 18, 2014)

I have a readout of spindle speed!  Is it accurate?  Onward and upward! (Yes I am excited.)


----------



## jumps4 (Dec 19, 2014)

great
what ended up being the fix?
steve


----------



## Transformer (Dec 19, 2014)

My son.  But he keeps no notes although he did read this thread before he plunged in.   If I figure out what he did I will pass it on.  In the mean time I sent him home to be with my one month old granddaughter.  Thanks to all.

Dennis


----------



## stupoty (Dec 19, 2014)

Transformer said:


> I have a readout of spindle speed!  Is it accurate?  Onward and upward! (Yes I am excited.)



Glad your making progress , i missed the response, i was thinking to double check the sensor was senseing, seems it is though 

stuart


----------

