Top 3018s
Genmitsu Aluminum Spindle Holder
Z-axis mount · 69 mm or 65 mm · machined aluminium

Genmitsu Aluminum Spindle Holder

A machined aluminium clamp that swaps onto Genmitsu's aluminium Z carriages with four screws, so a compact trim router can take the place of the 775 motor.

  • Clamp diameter69 mm, or 65 mm version
  • MaterialPrecision-machined aluminium
  • Fitting4 screws, after removing the stock mount
  • CarriesA trim router with a matching collar
  • 3018 fit3018-PRO with Z Assembly V2; 3018-PROVer V2
  • Weight0.27 kg (69 mm), 0.29 kg (65 mm)
Suits
  • Putting a compact trim router on a Genmitsu aluminium Z
  • Owners who also run, or plan to run, a larger Genmitsu machine
  • Hardwood work where the 775 runs out of torque
Skip if
  • A stock 3018-PRO with the moulded Z carriage: fit the Z Assembly V2 first
  • Fine PCB and small-bit engraving, where a 775 at high rpm is better suited
  • Spindles with a 52 mm body, which need a 52 mm clamp
Get it here
Kit contents

Match the clamp to the router's collar

69 mm clamp
See this kit
65 mm clamp
See this kit

A trim router on a Genmitsu Z: 65 or 69 mm

Genmitsu's aluminium spindle holder is a bolt-on clamp for its own aluminium Z carriages. It comes in two bores, 69 mm and 65 mm, and exists for one purpose: replacing the 775 motor with a more powerful handheld router. Genmitsu frames it as the step to a stronger router on the 3018-PRO, the 3018-PROVer V2 and its larger 3020, 3030 and 4040 machines.

The two versions share the same design:

  • 69 mm: 88 × 98 × 36 mm outside, 0.27 kg.
  • 65 mm: 88 × 91 × 36 mm outside, 0.29 kg, model ZC65.
  • Both: precision-machined aluminium, four-screw mounting and a hand-tightened clamp.

Choosing between them comes down to one measurement. Wrap calipers around the round collar of the router's motor body, where a handheld router's base would normally clamp. Compact routers are commonly made with 65 mm collars, and some DeWalt-style models use 69 mm, but models differ, so measure your own.

Measure, do not guess. A clamp a millimetre too big never grips properly, and a router that slips in its mount changes the depth mid-cut. If the collar reads between sizes, a thin shim is safer than forcing a tighter clamp.

Genmitsu cites greater stability and less running noise over the stock mount, with a screw pattern that keeps the spindle level. The aluminium body is stiffer than any moulded carriage, and that stiffness shows in hardwood more than anywhere. On a 3018, though, the gantry and rods carry the same load as before, so the frame, not the clamp, sets the final limit.

Router collar sizes are the first question; the second is whether the Z carriage below can take the mount at all.

Measurements

The spec log

SpecValue
MakerGenmitsu
Clamp diameter69 mm; 65 mm version (model ZC65)
Outside dimensions, 69 mm88 × 98 × 36 mm
Outside dimensions, 65 mm88 × 91 × 36 mm
Weight0.27 kg (69 mm); 0.29 kg (65 mm)
MaterialPrecision-machined aluminium
ClampingHand-tightened, manual lock
Installation4 screws, after removing the stock carriage mount
Genmitsu Z kitsAluminum Z Axis Assembly V2
3018 machines3018-PRO (via Z Assembly V2), 3018-PROVer V2
Larger Genmitsu machines4040-PRO, 4040-PRO MAX, 4040 Reno, 3020-PRO MAX V2, 3020-PRO Ultra, 3030-PROVer MAX
HoldsA trim router or spindle with a 69 mm or 65 mm collar
In the box1 spindle mount

Oak profiles and 1/4-inch bits with a trim router

A trim router brings two things a 775 lacks: much more motor power and, on most US models, a 1/4 in collet. That opens up bits with thicker shanks and deeper profiles. It also brings weight, noise and a high minimum speed.

What the swap opens up on a 3018-size bed:

  • Hardwood signs: oak and maple letters cut deeper per pass without the motor bogging down.
  • 1/4 in shank bits: larger V-bits, bowl bits and surfacing bits for flattening the bed or a blank.
  • Spoilboard surfacing: a wide flat bit levels an MDF board faster than a 1/8 in end mill.
  • Steadier finishes: more torque means fewer stalls on the corners of a pocket.

And what it costs:

  • Weight on the gantry: a trim router is far heavier than a 775, and every rapid move carries it.
  • Speed control: most trim routers set rpm on their own dial, so GRBL can only switch them on and off through a relay, or not at all.
  • Minimum speed: compact routers usually start around 10,000 rpm, which is fast for plastics and aluminium.
  • Noise and dust: a trim router is loud, and a dust shoe matters more than before.

On a 3018, the trim router works best as a hardwood and surfacing tool. PCB isolation and fine V-bit lettering stay better on a 775 turning high rpm with a 1/8 in bit. For material-by-material limits on the frame, read what a 3018 cuts.

In the lineup

Where it lands among 3018 gear

3018 CNC machine models by type, September 2026. Highlighted: Genmitsu Aluminum Spindle Holder.

Four screws on the Z Axis Assembly V2: fitting and squaring

The holder bolts to Genmitsu's aluminium Z carriage in place of the mount that is already there. On a 3018-PRO that means the Aluminum Z Axis Assembly V2 has to be fitted first. On the 3018-PROVer V2 and the larger Genmitsu frames, the carriage is already aluminium.

The Z Axis Assembly V2 replaces the moulded carriage and ships with 43 mm and 52 mm mounts; this holder swaps in for either. The sequence:

  1. Power off and remove the motor or spindle from the current mount.
  2. Undo the four screws holding the stock mount to the carriage and lift it away.
  3. Offer up the new holder, start all four screws by hand, then tighten them in a cross pattern.
  4. Slide the router into the clamp at a height that leaves the bit tip about the job's depth above the bed at the top of Z travel, then lock the clamp.
  5. Check the router's cable path through the full X and Z travel.

Squaring comes next. A router that leans a fraction of a degree leaves ridges on every surfacing pass. Fit a long straight bit, jog it along X and Y a few millimetres above a flat surface and look for a changing gap; adjust before the first real cut.

Plan the switching before the first cut. The router plugs into the wall, not the controller board, so decide whether it is switched by hand at each job or through a relay driven by the board's spindle output. Keep a hand near its own switch either way.

Longer bits and a heavier motor both eat into usable Z depth. Measure the gap from the collet to the bed with the router in place, because thick blanks may no longer fit. The upgrade order puts this mount after the Z assembly and a probe, not before.

Swap-ins

Three other ways to go

69 mm, 65 mm or a 52 mm spindle instead

The spindle holder is one of three ways past the 775 on a 3018. Which is right depends on the motor that goes in it, and on the owner's patience with extra weight and wiring.

RouteMotorSpeed controlBest for
65 or 69 mm Genmitsu holderTrim routerRouter's own dialHardwood, surfacing, 1/4 in bits
52 mm mount (Z Assembly V2 or Srliya)300–500W spindleIts own controller, often with PWMAluminium, brass, mixed work
43 mm 775 mountGS-775M or similarGRBL PWMPCB, acrylic, fine lettering

Pick the 65 or 69 mm holder when:

  • You already own a compact router with a matching collar.
  • The work is mostly hardwood and flattening.
  • You own, or plan to move to, a 3020, 3030 or 4040 Genmitsu, where the same holder fits.

Pick a 52 mm spindle instead when:

  • Speed should be set from G-code, not a dial.
  • Aluminium and brass are regular jobs.
  • You want lower weight on a small gantry.

Before ordering, check three things: the router's collar diameter, the carriage it will bolt to, and the weight of the router against the size of the gantry. If any of the three is doubtful, the smaller 775 or 52 mm routes are the safer build.

For many 3018-PRO owners, the Z assembly with its 52 mm mount is the more balanced step. The holder earns its place when a router is already on the shelf. Past that point, a 3018 Pro Max frame with a 500W spindle and 80 mm of Z may be the better buy.

Bench notes

Setup questions

Does the Genmitsu spindle holder fit a stock 3018-PRO?

Not on the moulded stock carriage. It swaps onto Genmitsu's Aluminum Z Axis Assembly V2, which the 3018-PRO needs first.

Should I buy the 69 mm or the 65 mm holder?

Measure the round collar on your router's motor body and buy the matching size. Compact routers are often 65 mm, but models vary.

Can GRBL control a trim router's speed?

Usually not. Most trim routers set speed on their own dial; the board can at most switch them through a relay.

How is the holder installed?

Remove the existing mount from the aluminium carriage, then fit the holder with four screws and clamp the router in it.