Genmitsu Offline Controller (PROVer V2)

The change is bigger than it sounds. A USB stream can stall when the computer sleeps, updates or loses the port, and on a two-hour relief carving that means a ruined blank. With the file on a card, the controller feeds GRBL directly and the job runs to the end with nothing else attached.

What the controller handles on its own:

• Running files from the SD card, start to finish.
• Jogging each axis, continuously while a button is held or in fixed steps with a tap.
• The spindle, switched on or off without loading a G-code file.
• Z tool setting with a touch probe, straight from the menu.

Genmitsu reworked this version for better G-code compatibility. It can read some non-standard codes that trip up simpler controllers, which avoids jobs stopping or shifting partway through when a CAM program writes a line the controller does not expect.

The unit is small, 4 by 2.9 inches and 0.13 kg, so it sits beside the machine or hangs off the frame without getting in the way of the gantry.

Here a long press moves the axis continuously until the button is released, and a short tap moves it in a fixed increment for the final approach. It works like a coarse and fine adjustment, and it turns a two-minute setup into a few seconds.

A typical setup on a maple coaster blank:

1. Clamp the blank and power up the machine with the controller attached.
2. Hold the X and Y buttons to run the bit over the lower-left corner of the blank.
3. Tap to fine-position, then set X and Y zero.
4. Place the touch probe on the blank, clip it to the bit and run the Z probe routine from the menu.
5. Remove the probe, choose the file on the SD card and start the job.

Running Z setting from the controller is the key detail. Without a menu item, probing means writing a probe command into a G-code file on the card. Here it is a menu item, so the same file works whatever bit or stock thickness is on the machine that day.

The spindle switch helps in a different way. Turning the spindle on by hand before a job lets you listen for a bad bearing or a bit that runs out of true, without committing to a toolpath. On maple, a hard wood that punishes a wobbling bit, that small check is worth making.

• Keep the probe plate clean; a chip under it raises zero.
• Check the spindle direction on the first run after any spindle swap.

Every major hobby CAM program can write GRBL-flavoured G-code. In Fusion 360, choose the GRBL post-processor; in Carveco and Easel, pick the GRBL or 3018 machine profile. The result is a plain text file, usually ending in .nc or .gcode.

Habits that keep offline jobs trouble-free:

• Units: export in millimetres, so the file opens with G21 and matches how the machine thinks.
• Spindle speed: make sure the S values in the file suit the spindle fitted today, not a default from another machine.
• Safe height: set a clearance height above the tallest clamp.
• File names: keep them short and plain, with no spaces or special characters. Small controllers read simple names most reliably.
• One job per file: separate roughing and finishing into two files if they use two bits, so each can be probed after the bit change.

Test new files with the bit raised well above the stock first. Set Z zero 10 mm or so above the surface and run the job in air. The spindle traces the shape without cutting, and a wrong origin or a flipped axis shows up before it costs a blank.

The controller's improved reading of non-standard codes is a safety net, not a licence. A clean GRBL post still gives the most predictable run. For choosing the CAM program itself, see 3018 CNC software.

For a PROVer V2 owner the choice is clear. This controller and the MPG handwheel are the two listed for the V2. The handwheel is better for positioning by feel, with x1, x10 and x100 steps; the offline controller is the one that runs whole jobs.

The fit checks for this controller:

1. The machine is a PROVer V2, a 3020-PRO MAX V2 or a 3020-PRO Ultra, not a V1.
2. You have an SD card and a way to write it from your computer.
3. Your CAM program exports GRBL G-code.

The card does not retire the laptop. It stays useful for designing and for the first run of a new file over USB, while proven jobs move to the card. Repeat work, like a batch of twenty engraved coasters, is where the card pays off most.

Genmitsu also sells the PROVer V2 bundled with this controller, which suits buyers who know from the start that the machine will live away from the desk. The Genmitsu 3018 line-up covers the V2 and its siblings.