Genmitsu 3040 MDF Spoilboard

It is the same idea as the short board, scaled up. A layer of MDF sits between the bit and the aluminium table, takes the scars of through-cuts, and gets surfaced flat again when it wears. The difference is the footprint and the thickness:

• Footprint: 30 by 36 cm, sized to the extended Y-axis instead of the original 18 cm.
• Thickness: 15 mm, against the 12 mm of the common 3018 boards.
• Holes: threaded holes come fitted, so clamps screw in without extra hardware.

Genmitsu makes it for its own extension kit on the 3018-PRO and 3018-MX3 series, and the two are also sold together as a set. On a frame extended with a different kit, measure the table and its mounting points first, since hole positions are set for Genmitsu's version.

MDF suits a bed this size for the same reasons as the smaller board. It is uniform all the way through, soft enough to forgive a mistaken plunge and cheap enough to replace. Its weight, 1.2 kg, adds a little mass to the table without loading the Y stepper beyond what a thick slab of stock would.

A board longer than the travel is normal and useful. The bit cannot reach the very ends, but the extra MDF gives room for clamps beyond the cutting area, so they never sit in the toolpath. Plan the design inside the machine's real travel, and use the margins for holding.

A long plywood sign, step by step:

1. Surface the new board once so it is parallel to the gantry across the full length.
2. Lay the plywood with its long edge along Y, clamped at both ends outside the design.
3. Zero X and Y on a corner, and Z with a probe on the plywood face.
4. Carve the lettering with a V-bit, then cut the outline with a 1/8-inch flat bit and small tabs.
5. Cut the outline 0.3 mm into the board so the last veneer parts cleanly.

Plywood brings its own quirks. Birch ply is flat and consistent, while construction ply can hide voids that tear out on a through-cut. Thin ply bows on a long bed, so clamp or tape the middle as well as the ends.

• Check that the gantry clears clamps at both ends of the Y travel before starting.
• Run the first outline pass slower than usual; long stock vibrates more than a small blank.
• Keep tabs at least 3 mm wide in ply so the sign does not break free early.

A 12 mm board gives up usable thickness sooner, because the threaded holes and screws need material around them. With 15 mm, there are more passes to spend before the board is too thin to trust. On a bed this long, surfacing is also a longer job, so fewer replacements mean less time.

Surfacing a board this size on a 3018 frame:

• Use the widest flat bit the collet takes; a larger bit means fewer passes across 36 cm.
• Cut 0.2 to 0.3 mm deep with a stepover around 40 percent of the bit width.
• Run the pass along the long axis, so each line of the pocket is a single long stroke.
• Vacuum between passes; loose MDF dust under the bit leaves a rough patch.

The threaded holes take clamps directly. Genmitsu describes the board as working with most bench clamping systems, which on a 3018 usually means T-track mini hold-downs or low-profile side clamps screwed into the holes. Tighten them to snug, not hard; threads in MDF strip if they are cranked every day.

Keep water and oil off the board. MDF swells when it soaks up liquid, and a swollen patch lifts the stock. Aluminium work on an MDF bed should run dry, with an air blast for chips if needed. For wood, acrylic and PCB, the board needs nothing but surfacing and a vacuum.

The aluminium base is the structural piece. It adds rigidity to the extended frame and takes T-slot clamps anywhere along its slots, but a bit that goes through the stock hits metal. The MDF board is the sacrificial piece. Put together, the aluminium gives stiffness and the MDF takes the cuts.

Worth confirming on the frame first:

1. That the machine is a 3018-PRO or 3018-MX3 series frame, not a PROVer V2.
2. That the Y-axis extension is fitted, or ordered at the same time.
3. That your clamps thread into the board's holes, or that T-nuts fit your aluminium base.

One more consideration is Z height. A 15 mm board plus an aluminium base under it raises the work surface, and a stock 3018-PRO has about 45 mm of Z travel. Thick stock, a long bit and a tall clamp can use that up quickly, so check the clearance with your thickest planned job before screwing the board down. Genmitsu's aluminium Z-axis assembly V2, which raises effective Z range to 56 mm, is one answer when it runs short.

If the extension is still a plan, the Genmitsu 3018 Y-axis extension kit comes first, and the board after it. The upgrades logbook places the bigger bed among the other parts, and the 3018-PRO entry covers the machine it extends.