Zhong Hua Jiang 775 Spindle Motor

Its selling points fit in a short list:

• Speed: 20,000 rpm rated, with speed adjusted from software through the board's PWM output.
• Bearings: double ball bearings on the shaft rather than plain bushings.
• Tool holding: a 5 mm ER11 extension shaft, the same collet system most 3018 end mills and V-bits already use.
• Fit: the maker lists every 3018 series router as compatible.
• Life: the maker claims twice the working life of an ordinary 775.

For context, Twotrees quotes 7,000–9,000 rpm for the 775 on its TTC3018. A 20,000 rpm rating is more than double even Twotrees' upper figure, which matters most for small-diameter bits.

Two situations make this motor worth ordering. The first is a stock spindle that has grown loud, slow or rough, which on a brushed 775 usually means worn brushes or bearings. The second is an owner who wants more rpm for fine engraving without rebuilding the Z carriage. In both cases the motor drops into the existing 775 holder, and nothing else on the machine has to change.

Where the higher speed shows first:

• PCB isolation in FR4 or FR1: 0.1 mm V-bits and small end mills leave cleaner copper edges at high rpm.
• Fine lettering in hardwood: small V-bits in walnut or maple leave less fuzz.
• Acrylic engraving: quick, shallow passes give a crisp line, provided the feed keeps up.
• Sign cutting in plywood: a 1/8 in two-flute end mill can run a steadier feed.

Speed has a flip side. A fast spindle with a slow feed rubs instead of cutting, and plastics punish that first: acrylic softens, welds onto the bit and fuses the slot. If chips come off as dust or melted strings, raise the feed or lower the spindle speed until they come off as clean curls.

Aluminium stays marginal on any 775, however fast it spins. The motor has speed but little torque, and the rest of a basic 3018 flexes before the motor stalls. Settings by material are in the materials entry.

1. Cut the power and pull the plug, then remove the bit and collet from the old motor.
2. Photograph where the two spindle wires enter the controller board, noting which is positive.
3. Loosen the holder clamp screws and slide the old motor out.
4. Slide the new motor in at the same height, so the collet sits where the old one did, then tighten the clamp evenly.
5. Connect the wires with the same polarity, then run the spindle at a low speed with no bit fitted.

Check the direction of rotation before cutting anything. Standard end mills and V-bits are right-hand cutters and need clockwise rotation seen from above. On a brushed DC motor, swapping the two wires reverses the direction, so a spindle running backwards is a two-minute fix.

Then set GRBL's maximum spindle speed to match the new motor, so PWM commands map onto its real range. Setting number 30 in the GRBL list holds that value; how to change it from Candle or UGS is on 3018 CNC software. Finally check the collet: runout on an extension shaft shows up as fuzzy slots and snapped small bits.

The Zhong Hua Jiang motor suits these owners:

• The stock motor is tired, and the aim is to get cutting again quickly.
• The work is wood, plastic and PCB, where rpm counts more than torque.
• The wiring can be kept tidy, or a capacitor added if the USB link drops.

Buy two if the machine runs every week. A spare 775 in the drawer turns a worn-brush failure on a Saturday into a ten-minute swap instead of a week without cutting.

The GS-775M suits owners who want the noise suppression already on the motor and a collet set in the box. Both motors are rated 20,000 rpm at 24V, so cutting results on wood and plastic will be close.

A 52 mm spindle is a different project: a metal Z carriage, a separate power supply and more weight on the gantry. It is the right step for regular aluminium and brass work. The upgrade order shows where each spindle step fits, and the aluminium Z assembly is the usual first move toward a 52 mm motor.