Anycubic Ace PRO mod Spool Holder

All functions, including filament rewinding, are fully operational. This mod has no drawbacks.

A small update. It may not be obvious, but in order to make the coils spin easily, wash the bearing bushings in any solvent (such as purified gasoline) to remove the internal grease.

Update. I’ve added a 1-slot mod along with a fully 3D-printed axle and cylinder (no bearings or threaded rods required). However, I strongly recommend using the printed parts for testing purposes only.

Foreword

Hello everyone. I’ve been searching for the perfect MMU for my VZBot for a long time. In my opinion, the Python AMS mod for Bambu Lab is the ideal engineering solution in terms of performance and versatility. I’ve worked with it extensively, and it’s simply magnificent. Unfortunately, no one has adapted it for other Klipper-based printers yet (I might take this on myself soon). Currently, I’m using my Hard mod PICO as an MMU — it works well, but I’ve always wanted something more elegant in terms of aesthetics.

Why I decided to mod the Anycubic Ace Pro

I like the look of the Ace Pro, the fact that it has a drying function, the built-in Feed Assist, and the fact that it has four dedicated output channels (exactly what I needed for my VZ). As soon as I learned it was possible to connect it to Klipper, I decided that sooner or later, I would test it with my VZBot. I knew what I was getting into and was prepared for the issues inherent to this MMU design (which are the same as the Bambu Lab AMS):

1. Poor performance with certain cardboard spools.
2. Poor performance with non-standard spool diameters (especially those smaller than 200mm).
3. The inability to fit wide spools (this is an issue I haven't been able to solve).

What I attempted to do

Inspired by the Python AMS, I wanted to achieve a similar design where the spool sits on a hub regardless of its size, while the drive rollers only lightly nudge it during rewinding. At this stage, I have successfully developed a design that implements this mechanism. I’ve already logged several dozen print hours with active filament swaps—including using cardboard spools with terrible edges—and everything works perfectly. Filament rewinding has become much smoother, and it’s now easier for the Ace Pro to feed the filament (which is crucial for an MMU).

The Design

The result is a modular design that allows you to modify either two or all four slots. Installation is straightforward—essentially, it’s just a frame where the spools sit on hub-mounted axles.

BOM (Bill of Materials)

• 8x M8 nyloc nuts
• 4x M8*82 threaded rods (studs)
• 8x 608 bearings
• 3x M3*8 countersunk screws
• 3x M3 nuts
• 2x M2.5*10 screws (optional)
• 2x M3*20 screws (optional)

Materials

I recommend printing all components using ABS-GF10 (for both aesthetics and reliability) or at least PETG. Keep in mind that when modified, the Ace Pro can reach temperatures of up to 70°C, making ABS an excellent choice for this application.

Assembly

The assembly is straightforward—to reiterate, you can install just the left or the right module independently. Alternatively, you can install both modules and fasten them together in the middle with screws. Mounting the unit to the MMU casing is also optional. All key assembly points are clearly visible in the photos.

I broke off the limiters in the Ace Pro — they are no longer needed. It is also necessary to remove the rear rollers

P.S. This works absolutely brilliantly—honestly, I didn't expect it to perform this well!