Genmitsu GS-775M Spindle Motor

Speed matters more than raw power for the bits a 3018 uses. A 1/8-inch end mill or a 20° V-bit cuts cleanly when its edges move fast, and a slow spindle forces a slow feed or leaves rough, torn edges in wood and melted edges in acrylic.

• Voltage: 24V DC, the same as the stock motor on most 3018 boards.
• Speed: 20,000 rpm, which Genmitsu puts at 10,000 rpm above the original motor.
• Shaft and collet: a 5 mm shaft carrying an ER11 collet set, so standard 1/8-inch and 3.175 mm bits fit.
• Bearings: double ball bearings, and the motor runs clockwise or counter-clockwise.
• Suppression: a noise-suppression PCB already fitted, which keeps brush sparks from upsetting the controller's USB link.

That last point is easy to overlook. Brushed motors create electrical noise, and on a 3018 it can show up as dropped USB connections mid-job, so a suppression board on the motor is a small detail with a real payoff.

The motor is a speed upgrade, not a power upgrade on the scale of a 500W spindle. The upgrade order entry shows where it sits among the other parts.

The worked numbers show why the GS-775M matters. With a 1/8-inch end mill of two flutes taking a 0.02 mm chip per flute, the arithmetic gives 400 mm/min at 10,000 rpm and 800 mm/min at 20,000 rpm.

These are illustrations of the formula, not maker figures. The frame's stiffness and the depth of cut decide how much of that feed a 3018 can hold without chatter.

• Cast acrylic: a single-flute O-flute bit at high rpm and a brisk feed clears chips before they melt and re-weld.
• Hardwood: two-flute bits, shallow passes of 0.5 mm or so, and the higher feed the extra speed allows.
• PCB isolation: V-bits cut cleaner copper edges at 20,000 rpm with less burr.
• Brass and aluminium: engraving in light passes; the motor's speed helps, its torque does not.

The materials entry has starting depths for more stock types.

1. Switch off at the wall, then disconnect the stock motor's leads at the board.
2. Loosen the holder clamp and slide the old motor out, noting how far it sat through the mount.
3. Fit the ER11 collet to the new motor's 5 mm shaft and tighten it before mounting.
4. Slide the GS-775M in to the same depth, clamp it, and connect the leads to the spindle output with the polarity the old motor used.
5. Run the spindle at low speed and confirm it turns clockwise, looking down from above.

GRBL needs one setting changed. Setting 30 holds the maximum spindle speed, and it should read 20000 so that S20000 in the G-code means full speed and S10000 means half.

The supply is the most common snag. The GS-775M draws a high current at start-up, and older 3018 adapters may trip their protection and cut out as the motor spins up.

• Dust shoe: a 42 mm shoe with two 4 mm screw holes fits this motor; one bundle includes it.
• Collets: keep collets clean and never tighten the nut without a bit in it.
• Brushes: brushed motors wear; a drop in speed or more sparking means the brushes are near the end.

For Genmitsu's aluminium Z assembly, the 43 mm mount takes this motor too.

The GS-775M is the least disruptive. Nothing on the frame changes, and every holder, dust shoe and collet built for a 775 keeps working. It also keeps the old motor useful: the stock 10,000 rpm unit becomes a spare, or a dedicated motor for jobs that prefer low speed, such as larger surfacing bits in soft wood.

A 500W spindle trades speed for torque, and it needs a stiffer carriage to use that torque. The Genmitsu aluminium Z-axis assembly V2 is the usual first step on a 3018-PRO for that route.

• Pick the GS-775M for cleaner cuts in wood, acrylic and PCB with no other changes.
• Pick the bundle with the adapter if the machine still has an early supply.
• Pick the dust-shoe bundle if chips already cover the bench after every job.
• Plan for 500W if aluminium pockets and brackets are the goal.

Before ordering, check the holder diameter and the supply's rating, and confirm the board's spindle output handles the motor. Most 3018 boards drive a 775 directly, and the CNCTOPBAOS and RATTMMOTOR boards state support for spindles up to 20,000 rpm.