PwnCNC → Masso G3 Upgrade: My Install Notes, Mods, Fixes, and What Actually Happened
I just finished installing the PwnCNC Masso Conversion Kit on my Onefinity, and I wanted to document the process for anyone else considering the upgrade. This isn’t a hype post — this is what actually happened, what I had to modify, and what I learned along the way.
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Mechanical Changes & Gantry Swap
One of the first decisions I made was moving the X axis stepper from the right side to the left. I didn’t want to rebuild my table or shift the whole machine away from the wall, so the gantry swap made the most sense.
Fortunately, Onefinity designed most of their machine with mirrored components, so the swap is very doable.
What I had to do
• Disassembled the gantry and rotated the top piece 180° to maintain the correct offset for the Stiffy tube.
• The stock coupler didn’t fit the larger stepper shaft. I drilled the original coupler out to 5/16" and hand filed it until it fit. It works, but long term I’d still recommend ordering the correct coupler.
• The prox mounts are shop fabricated, not from any vendor.
• On the Z slider, I epoxied an L bracket for mounting trigger. Works great with a spindle mounted dust boot, but it will interfere with a fixed boot I think. -
Homing Sensor Changes
I removed the old screw used for stall homing and switched fully to proximity sensors.
How I mounted them
• Tapped through the foot support and the tube to mount the prox sensors.
• After running the machine, I’d recommend mounting the sensors on the outside of the rails instead of the inside — this will avoid any interference and gain a little more X travel -
Grounding, Shielding & Bus Bar Setup
Electrical noise becomes a real factor with a VFD, spindle, proximity sensors, and Masso inputs all sharing the same environment. After opening a few connectors and realizing the cable shields weren’t bonded to the cabinet, I built a proper grounding system instead of relying on whatever the harness happened to provide.
What I installed
I added a dedicated grounding bus bar tied every shield drain and machine frame component into it:
• Shield drains from all control cables
• Shield drains from all spindle/VFD cables
• Ground wires to both Y rails
• Ground wire to the X gantry
• Ground strap for the dust hose bleeder from the helix wire
Everything terminates at the same point, keeping the system at a single electrical potential and preventing floating grounds or noise loops.
Out and Back vs Coil
I avoided coiling extra control and power wire.
Result
The machine is noticeably more stable. Homing is cleaner, spindle control is quieter, and Masso inputs behave consistently. -
Homing Behavior
Once everything was wired, I ran straight into the classic Masso dual motor homing freeze: after the initial pull off, the B side would stop dead with “Homing… please wait.” No alarms, no movement — just stuck.
At first, I thought I had somehow dragged old Onefinity issues right back into my shop. I checked the Onefinity site and saw the same symptoms documented there, and my immediate reaction was:
“Perfect… I just brought Onefinity problems back with this upgrade.”
But after digging into the Masso documentation, I found something important. Masso lists this exact behavior under:
“Homing completes but machine flashes ‘Homing’ and does nothing.”
And the first cause they list?
Auto Tool Zero enabled but not configured.
Masso will hang in the homing state if Auto Tool Zero is turned on but the tool setter isn’t set up correctly.
The fix
• Disabled Auto Tool Zero
• Re ran homing
• Machine completed normallyWith all of that combined, homing is now solid and production ready.
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Spindle Scaling & VFD Tuning
The spindle powered up immediately, but the RPM scaling was completely wrong.
• Command S6000 → spindle showed ~600
• Command S18000 → spindle showed ~1800
A perfect 10× mismatch.
I went back and forth trying to track it down, but the breakthrough came when I pulled the actual Redline VFD documentation from their website. That’s when it became clear the VFD had been running on a custom profile that didn’t match Masso’s control method at all.
What I did
• Performed a full factory reset on the VFD
• Re entered every parameter exactly as Redline specifies
• Verified motor data, max frequency, and analog input mode
• Reconnected Masso and tested again
Current state
Spindle responds smoothly
• RPM tracking is consistent
• Minimum RPM Masso can command is now 6000, which isn’t correct
• The remaining scaling issue will need a deeper dive into the VFD’s hidden or secondary analog parameters
Even with the mismatch, the spindle runs strong and stable — but the last bit of scaling cleanup is still on the to do list.
Final Thoughts
This upgrade isn’t plug and play — it’s an integrator level project. But once everything is tuned, the machine feels tighter, smoother, and more capable than it ever did with the Onefinity Black Box.
At some point in this upgrade, I’m pretty sure I voided the warranty so hard it left the building. And honestly, that’s fine — because if I called support right now, we all know exactly how that conversation would go: “It’s EMI” Try running without your dust collector or maybe it’s the GFCI problem.
