I’m in the process of converting my Grizzly G0602 Lathe to CNC using a PMDX-424 through a PMDX-407 Spindle Speed Control board.  I have pretty much everything running except the spindle control.  I’m using a 200 count encoder with an index and have tried several settings with only marginal success.

I’ve set the “Encoder Config” to “Bi-directional (quadrature) Encoder with Index” with Encoder counts per revolution set to 200.

I have selected “Spindle Conf’s” “Spindle Speed Control” to “PWM” with its “Min PWM Duty Cycle” set at 3 (because higher values seemed to change the indicated RPM when it’s working?).

If I select “Measure RPM from the Encoder” I get no “True RPM” reading when I run the spindle, but I do get a “True RPM” reading if I select “Measure RPM from the Index input”.  However, in neither case can I run a threading G-Code even one developed using the conversational tab. Although both selections provide A, B, & C indications with the PMDX-SmartBOB I/O Status Screen.

With both, I also get an Error Message of “PMDX: Encoder mode has index, cannot set Encoder Position” and the threading G-Code stops on the second G76 line?

I tend to suspect that the Error Message should be telling me something I’m just not bright enough to know what it is?  On the other hand, it could be something else entirely.

Any insights would be greatly appreciated.

Here’s the threading G-Code I developed using the conversational threading option:

N0 (Machine type - MachMotion Lathe Canned Cycles)
N5 (Filename: C:\Mach4Hobby\GcodeFiles\Conversational Partial Facing Cut Test Code.tap)
N10 (Generated on 11/17/2020 at 6:58:00 PM)
N15 G00 G40 G54 G64 G80 G90.1 G99 G18 G20 (Safe Start Block)
N20 %

N25 %
N30 (Starting Gcode for Threading Cycle: ThreadingCycle-0)
N35 G50 S1500 (Spindle Speed Cap)
N40 G00 G40 G54 G64 G80 G90.1 G99 G18 G20 (Safe Start Block)
N45 %

N50 %
N55 T1212 (Tool Change)
N60 G99 (Feed per Revolution)
N65 G97 S500 (Constant Speed)
N70 M03 (Spindle Forward)
N75 M07 (Mist)
N80 G00 X0.5200 Z0.0200  (Rapid move to Clearance Height)
N85 G76 P020030 Q0.005 R0.001 K1
N90 G76 X0.435 Z-1.0 R0.0 P0.0325 Q0.005 F0.0769
N95 G80
N100 (End Gcode for Threading Cycle: ThreadingCycle-0)

N105 %
N110 M09
N115 M05
N120 M30
N125 %
N130 (End Gcode file)
N135 %