Sainsmart Genmitsu 3018-PRO

About the Machine

The Genmitsu 3018-PRO has a 300 x 180 x 45 mm working area, a 20,000 RPM spindle, and 1.7 A stepper motors on round 10 mm (0.4 in) smooth guide rails.

Cut Settings on this Machine

Every cut starts with one formula: Feed Rate = Spindle Speed (RPM) x Chip Load x Number of Cutting Edges (flutes). Chip load is the thickness of material each cutting edge removes in one revolution of the bit. This number comes from the manufacturer of the bit, which publishes a chip-load chart for each bit diameter and material. Look up your exact bit and material, start from the middle of the published range, and you have the third number in the formula. The chart below shows the recommended spindle speed for each material and bit type.

The 3018-PRO's spindle is rated to 20,000 RPM on its own product page (a sibling comparison table lists an older 775 motor at 9,000 RPM instead; see the warning on this entry), which covers the full chart, so dial the spindle to whatever the chart recommends for the material and bit rather than running it pinned at max. Depth per pass is where the machine itself matters. A truly rigid machine with a powerful spindle can cut as deep as the bit is wide in a single pass, but that takes real spindle torque, a drive train and clamps that hold firm, a gantry that will not flex, and enough mass to soak up vibration. This is a small DIY kit on round 10 mm smooth guide rails, well short of that bar, so take shallower passes regardless of what the spindle can spin. Push too deep and the bit deflects and chatters, leaving scalloped edges, or it rubs instead of cutting and burns the material. The fastest way to dial in a cut is to see what has already worked for other people.

Worked example for feed rate: 1/8in (3.175mm) two-flute solid carbide end mill in hard wood. The chart says 16,000 RPM, and this spindle's rated 20,000 RPM ceiling covers that, so run 16,000. With the bit maker's 0.025mm per tooth (0.0010 in): 16,000 x 0.025 x 2 = 800 mm/min (31 in/min) feed. For depth per pass, start shallow and check Community Cut Settings in Easel for what works on this machine. If the cut sounds strained, reduce the depth, not the feed. Slowing the feed below the chip load makes the bit rub instead of cut.

Community Cut Settings shows the spindle speed, feed rate, and depth per pass other makers actually run for your machine, material, and bit.