Yet another C3 Index Pulse Board/Mach 3 mystery.

I am building the typical 7 x lathe CNC project and can’t get my C3 card to lock up with Mach 3. Here is what I have:

1. 56mm diameter disc with single 3mm slot.
2. C3 Index Pulse Board with photo sensor.

I made sure Mach 3 sees signal only when slot is aligned with sensor, and I used Mach 3 to identify Pin #15 with its “Automated Setup of Inputs.” Index signal in Ports & Pins correctly shows Pin #15 with “Active Low” checked.

C3 red LED lights up when slot is in proper position AND Mach 3 flashes the signal when rotated by hand but no spindle speed is displayed when lathe is running. Mach 3 flashes the signal when the spindle is really slow, but the light is not on at higher speeds. The C3 LED appears to lock solid either at lower RPM or fast (light is steady on)

I have tried several different settings of “Index debounce” in the General Logic Configuration screen including; 0, 1, 2, 3, 10, 50 and the default setting of 100. I have not changed the “Debounce Interval” (currently shows 500)

I have also tried both the “active low” and “active high” jumpers on the C3 board but this does not appear to change anything.

Any thoughts?

Thanks,
Gary

I would be more suspicious of the width of the slot. I use a piece of black tape on my pulley. I cover half of the pulley for it to work its best.

Debounce is for switches (limit, homing or Estop) that either mechanically bounce and the signal needs to be present for longer so Mach can recognize it from electrical noise or interference.

I am not sure of what index debounce truly does but I am guessing the same or similar action. I could see the switch for rpms really have some issues just due to how short of a time the signal is present.

In the later versions of Mach3, you have to have M3 active for the rpm to be monitored and displayed on the screen.
MDI M3 and see if it then shows movement.
M5 will shut it down.
If not controlling the spindle w/Mach, you need to keep M3 active. I put it in the inilit. block and make sure there is no M5 in any generated gcodes.
Russ

I also un-check Turn off Spindle under Program End M30 in general config.

Russ

I agree with Fastest that it could well be your disc/slot that is causing an issue. Try and increase the Dia of the disc to about 100mm and widen the slot to about 10mm.

Regarding the Index Debounce, lower will be better, I found in the past that anything above 0 caused delays and misreading but it will also depend on your hardware.
Hood

By the formula in the manual, the given disc dia. and slot width should be plenty adequate. (unless going well over 5k rpm)
When using only one slot, the "double wide" is not necessary.
But, who knows ..... damn manuals anyway. 

Russ 

A CD painted flat black when finished makes for a nice index disc. The few that I have made never worked right until the disc slot width was more than what the manual calcs said the slot should be.

RICH

  ..... damn manuals anyway. 

  

 

I'll narrow mine down shortly for a test. (I'm thinking it will work fine, at lower rpm's anyway)
Even when turned by hand at about 60, the dro should read something.

Russ

but no spindle speed is displayed when lathe is running.

You need to turn / click  the spindle button on to get the rpm to display.
Sorry missed that during a quick read of your post.

RICH

I have tested it enough to know that 1 piece of electrical tape starting at the center and going outward on the pulley( a 3/4" wide strip) will give me erratic readings . I turn that tape sideways creating a much bigger target and everything works great. Having a narrow slot is of no advantage that I have read (within Mach, EMC could be and is different). I believe it is only sensing the edge.

When and if I ever get around to installing the sensor into the spindle head, I am going to paint the back side of the pulley black for half of the circle leaving the other half polished aluminum. (seeing aluminum spinning forces me to polish it, I cant resist)