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Spindle Index Pulse Problem
« on: April 02, 2012, 03:15:27 PM »
Hello all,

Trying to give my lathe the ability to thread. I followed the advice given by Chris Humphris, and used an Optek OPB982T51Z optocoupler and made an interrupter wheel which is mounted on the spindle. Mach is seeing the pulse, as it does display an SActual value, but the displayed value swings/oscillates wildly. I've played with the slot width on my interrupter, I've toyed with the Index debounce value, changed active states, etc., to no avail. Whats going wrong?

The setup I'm using feeds the index pulse through a C23 BOB and SS. I've read a few other threads on here where people had better luck feeding the pulse direct through a PPort.

Any ideas?

Thanks,

Kevin

Offline Hood

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Re: Spindle Index Pulse Problem
« Reply #1 on: April 02, 2012, 03:21:51 PM »
I used OPB 916B or 917B and they worked very well. I used to power them from and put the input in to Port 3 on the SS.
I found on all machines from PP to SS that index debounce needed to be zero for me.
Hood
Re: Spindle Index Pulse Problem
« Reply #2 on: April 02, 2012, 03:46:00 PM »
It is unclear to me how to calculate the pulley ratio. I set my VFD manually to 700RPM. I then measured the actual spindle RPM using a tach, which showed 1250RPM. I assume the correct math is 1250/700=1.7857

I set Pulley 1 to 1.7857, then commanded Mach to run the spindle at 1000 RPM. The actual spindle speed was nearly 2000. I the tried arbitrarily changing the pulley ratio, but it never had an effect on spindle speed. Changing the max speed, however does. IE changing the max speed from 4000 to 8000 with my calculated pulley ratio brought the actual spindle speed closer to 1000. Whats going on here?

Meanwhile, the S Actual was reading 500,000RPM regardless of what I set index debounce to.

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Re: Spindle Index Pulse Problem
« Reply #3 on: April 02, 2012, 05:22:07 PM »
You need to set the max spindle speed in the Pulleys page to what your max spindle speed will be or you will get weird speeds.
Where is your sensor, if its on the spindle then you should not have any ratio or rather it should be 1, if its on the motor side then yes you need the ratio.
Hood

Edit, just to clarify, the ratio is simply used for Mach to set the displayed spindle speed and not for altering the commanded speed. For example if you have the sensor on the motor side and you have a 2:1 ratio then the spindle would be rotating twice as fast as the index pulse so setting a ratio lets Mach know that and the displayed spindle speed would be twice the motors speed.
« Last Edit: April 02, 2012, 05:26:10 PM by Hood »
Re: Spindle Index Pulse Problem
« Reply #4 on: April 03, 2012, 01:24:04 PM »
I think I understand. The max speed needs to be set to the maximum attainable speed with my setup.  I thought I was just arbitrarily setting it to the max speed I want to run at. Big difference there.

As for my index pulse problem, I think electrical interference from the VFD is causing the wild readings. Index debounce doesn't help this, and the shielded cable I'm using doesn't help much either.

Anyone have experience with VFD noise filters/line suppressors?

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Re: Spindle Index Pulse Problem
« Reply #5 on: April 03, 2012, 02:01:40 PM »
It is the Max you will be running it at, ie  the full 10v to your VFD, whatever that speed will be.

Shielded cable should be enough if you have the shield correctly grounded. Have you tried connecting the index direct to the SmoothStepper?
Hood
Re: Spindle Index Pulse Problem
« Reply #6 on: April 03, 2012, 02:22:34 PM »
I'm using a C23 BOB, which plugs directly into the SS. I tried soldering the index wire onto the BOB pin that plugs into the SS. Tried a pin on both ports, but that just gave me wild numbers all the time. 

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Re: Spindle Index Pulse Problem
« Reply #7 on: April 03, 2012, 02:24:51 PM »
I would use port 3 on the SS, I would also power it from the power pins on port 3, that is assuming it doesnt draw a huge amount of current.
Hood
Re: Spindle Index Pulse Problem
« Reply #8 on: April 03, 2012, 03:38:32 PM »
It draws 20mA. How do I use port 3 on the SS? Do I need a new SS plugin to utilize that?
Re: Spindle Index Pulse Problem
« Reply #9 on: April 03, 2012, 03:45:08 PM »
Nevermind. I looked at the SS manual and figured it out. I used Port 3 Pin 1 but I still just get crazy numbers.