OpenBuilds LEAD CNC Machine 1515 (60 x 60 in)

About the Machine

Openbuilds has shut down and no longer sells this model, but it remains fully supported in Easel for existing owners. The LEAD CNC Machine 1515 has a 1170 x 1250 x 90 mm (46.1 x 49.2 x 3.5 in) working area, ships without a spindle (OpenBuilds recommended a 65mm compact router, 710W), high-torque NEMA 23 stepper motors, and lead screw drive with dual C-Beam linear rails on the X axis.

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.

If this machine's spindle cannot reach the listed speed, run the spindle at its maximum and control the cut with feed rate. For 65mm trim routers, the DeWalt DW611 dial maps to: 1 = 16,000; 2 = 18,200; 3 = 20,400; 4 = 22,600; 5 = 24,800; 6 = 27,000 RPM.

The LEAD CNC 1515 ships without a spindle: OpenBuilds recommended pairing it with a 65mm compact router (710W), so your actual top RPM depends on that router’s own speed dial, most trim routers run somewhere between 10,000 and 30,000 RPM. Lead screw drive, dual linear rails on the X axis, and high-torque NEMA 23 steppers give it real rigidity, but at 1170 x 1250 mm it’s the largest gantry in the OpenBuilds lineup and still lighter-duty than an industrial machine. 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. Take shallower passes on a gantry this large, especially toward the middle of a long span. 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. 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 the OpenBuilds LEAD CNC Machine 1515 (60 x 60 in). 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.