Genmitsu Essential Accessories Kit

Each part solves a different problem on the bench:

• Emergency stop. A red mushroom button that latches down when pressed. A bit grabbing a clamp or a toolpath heading off the edge of the stock gets cut short with one slap.
• Z-axis touch probe. A plate and clip pair that lets the controller find the tip of the bit on its own, instead of guessing with a paper slip.
• Six micro limit switches. Normally open, momentary switches with 1 m three-pin leads, enough for the minimum and maximum end of every axis.

Together they turn a machine that only knows where it is relative to the last job into one that knows where its own frame ends. That matters most on long jobs, like a two-hour relief carving in basswood, where a lost position means a ruined blank.

The kit is built around Genmitsu's PROVer family. The 3018-PROVer and PROVer Mach3 have ports for these parts on their boards, and the 3018-MX3 is listed too. Owners of other frames can still use the parts, but the plug-and-go promise only holds for the three named machines.

The probe makes that repeatable. The clip goes on the bit shank, the plate sits on the maple, and the control software lowers Z until the bit touches the plate and closes the circuit. GRBL runs this as a G38.2 probe move, then the software subtracts the plate thickness and sets work zero.

1. Jog the bit roughly 5 mm above the plate.
2. Attach the clip to the shank, not the flutes, to protect the edges.
3. Run the probe command in Candle or UGS and let Z creep down.
4. Enter the plate thickness once; the software reuses it every time.
5. Remove the clip and plate before starting the spindle.

The same routine works on any flat stock: cast acrylic for a sign, a PCB blank for isolation milling or a pine offcut for a test pocket. On copper-clad board it is especially handy, because the engraving depth is so shallow that a paper slip's thickness is a real error.

Two habits keep it reliable. Blow chips off the plate before each touch, since a sliver of MDF under the plate lifts zero by its own thickness. Check the circuit before a real probe move by tapping the clip to the plate and watching the probe indicator in the software change state.

Six switches cover both ends of X, Y and Z. They are normally open, which means the circuit closes when the carriage presses the lever. Mount them where the carriage touches the lever a few millimetres before the hard stop, route the 1 m leads along the frame away from the spindle, and plug them into the board's limit headers.

Once wired, three numbered GRBL settings do the work. Each is typed into the console of Candle or UGS with a dollar sign in front of its number:

With homing on, a job interrupted halfway through a pocket in HDPE can be restarted from the same machine coordinates. The stock stays clamped, the machine homes again and work zero is where it was.

HDPE is a good test material for this. It cuts cleanly with a single-flute bit, but it melts and welds chips back into the slot if the feed stops, so a crash or stall shows up at once. A homed machine lets you rerun the pocket from a known point instead of re-zeroing on a half-cut surface.

• Test each switch by pressing it by hand and checking the pin state in the software before running the first homing cycle.
• Keep leads clear of the spindle cable; long unshielded runs can pick up noise and trigger false alarms.
• Set soft limits only once the homing cycle finishes cleanly every time.

The loose Genmitsu equivalents cover the same ground. The Genmitsu emergency stop button targets the 3018-MX3 and PROVer and resets through software after a press. The SainSmart Z-axis touch probe fits the 3018-PRO and PROVer and works with Candle and Mach3. The Genmitsu six-pack of micro switches matches the kit's switch count and 1 m leads.

Owners of other frames have other routes:

• 3018-PROVer V2: the kit does not name it. The photoelectric probe is listed for the V2, so start there and add switches listed for the V2 board.
• 3018-PRO and similar open frames: check the controller board for E-stop and limit ports first. A kit such as the CNCTOPBAOS switch and stop set is sized for 3018-PRO frames.
• 3018-MX3: named in the kit, so the plugs should match its board.

Three things to confirm on the machine first:

1. The exact machine name on the frame or the original box.
2. That the board has labelled headers for probe, E-stop and X, Y and Z limits.
3. That there is space on the frame ends to mount a switch where the carriage will reach it.

The payoff arrives on the first long job. A probe removes the guesswork from bit changes, switches stop crashes into the frame, and a stop button within reach ends a bad cut. For the full order of 3018 upgrades, see the parts and upgrades logbook, and for PROVer specifics, the Genmitsu 3018 line-up.