Interfacing BlackBox Motion Control System (ATmega328p version) with OTK-3 Knife

Hello all,

There was a previous post on a related topic of interfacing a tangential knife, but I didn't want to zombie-hijack the old thread so I made this post.

I'm trying to figure out if the Stepcraft OTK-3 can be interfaced with the BlackBox Motion Control System (the older ATmega328p version, though we could potentially upgrade if needed). The OTK connects to a D-Sub connector with the below pinout:

I have two primary points of confusion:

1. The BlackBox unit has a toolhead interfacethat has Gnd, PWM, DIR, and 0-10V connections. I was trying to figure out whether anyone had interfaced something similar. It seems like the OTK Pin 4 Direction can be handled with the BlackBox PWM pin similar to the plotting application, and the OTK Pin 6 can be handled with the 0-10V connection, but I am not clear on what would be connected (if anything) to the OTK pins 5, 12, and 13.
2. My other concern was that the plotting application (the closest analogue I found) requires flashing "CUSTOM GRBL firmware for 2 Axes + RC Servo" according to the above link, but for the oscillating knife we would still need the ability to raise and lower the knife to make different cuts. I was wondering if anyone had tried modifying the firmware to enable the third axis, or whether a generic GRBL image might be better?

I've reached out to Stepcraft to inquire what the function / signal type of the confusing pins are, but was hoping to check if anyone had had success with a similar module or approach on the BlackBox or similar hardware (or other insights into the difficulty or ease of integrating such a module).

Thanks for your insights and advice,

Mike

Edited to add Stepcraft link