---
title: "The Ploopy A+ keeps its old bearing mount. That is almost good news"
locale: "en"
url: "https://irz.fr/en/articles/ploopy-aplus-bearing-continuity-en"
markdown_url: "https://irz.fr/en/articles/ploopy-aplus-bearing-continuity-en.md"
category: "tech"
tags: ["open hardware", "trackball", "repair", "bearing", "QMK"]
published_at: "2026-08-20T08:29:00.000Z"
author: "Camille Morel"
translation: "https://irz.fr/fr/articles/ploopy-aplus-bearing-continuity-fr.md"
---

# The Ploopy A+ keeps its old bearing mount. That is almost good news

The new Ploopy A+ keeps the Adept bearing mount. That is awkward given complaints about the bearings, but it also preserves replacement parts and community mods.

Ploopy's A+ launch page gives you the expected new-model list first: eight buttons, two knobs, a detachable wrist rest, new QMK gestures and preorders starting at **CAD $99**.[1](https://blog.ploopy.co/the-aplus-is-finally-here-499) The more revealing detail is buried in the discussion below the announcement, where people immediately started asking whether old Adept modifications would fit the new case.

One user asks about static-bearing mods. Ploopy replies that **the Adept and A+ share the same bearing-mount design**, which means a mod plugging directly into that part of the Adept case should also fit the A+.[5](https://www.reddit.com/r/ploopy/comments/1vo4y4r/this_is_the_a_trackball_the_update_to_the_adept/) A few comments later, another owner describes replacing original bearings after rust made the trackball rough and recommends stainless replacements; Ploopy answers that it knows supporters have experienced problems with the bearings it ships, while carefully avoiding a promise of changed hardware.[5](https://www.reddit.com/r/ploopy/comments/1vo4y4r/this_is_the_a_trackball_the_update_to_the_adept/)

That exchange gives the A+ a stranger inheritance than a normal spec sheet would show. The old interface carries forward a reported problem, but it also carries forward the community's ability to work around it.

## Same interface

I checked the A+ repository at commit `cef2e28`, the revision published with the launch material. Its hardware appendix names three **MR63ZZ roller bearings**, each specified at 3 mm inner diameter, 6 mm outer diameter and 2.5 mm thickness, alongside two 6700-2RS bearings for the knobs.[4](https://github.com/ploopyco/aplus-trackball/blob/cef2e28abe79f6dec1dda76f80ee98e31b48ae60/docs/appendices/hardware.md)

The assembly guide then shows exactly where those small parts go: each MR63ZZ bearing is pressed onto a separate dowel with a printed jig, and the three resulting assemblies are pushed into dedicated holes in the 3D-printed upper shell.[3](https://github.com/ploopyco/aplus-trackball/blob/cef2e28abe79f6dec1dda76f80ee98e31b48ae60/docs/assembly-instructions.md) There is no mystery cartridge between the ball and its supports, just a bearing, a pin and a piece of printed geometry whose relationship is documented.

> Illustration: Three Ploopy A+ roller bearings installed in the 3D-printed upper case. Each bearing is a separate component pressed onto a dowel and inserted into the printed top. Credit: [Ploopy](https://github.com/ploopyco/aplus-trackball/blob/cef2e28abe79f6dec1dda76f80ee98e31b48ae60/docs/assembly-instructions.md).

Ploopy gives similar dimensions for the magnets and screws, then specifies a 45 mm ball with an acceptable range from 44 to 46 mm, even mentioning miniature snooker balls as an aftermarket source.[4](https://github.com/ploopyco/aplus-trackball/blob/cef2e28abe79f6dec1dda76f80ee98e31b48ae60/docs/appendices/hardware.md) Once the documentation is open, several parts that look specific to a niche trackball turn back into ordinary mechanical descriptions that another supplier can understand.

## Known friction

To be sure, one Reddit report cannot tell us how often an Adept fails. The owner says the supplied bearings rusted and produced rough cursor movement; that remains one user's account, useful as a documented failure mode rather than as statistics.[5](https://www.reddit.com/r/ploopy/comments/1vo4y4r/this_is_the_a_trackball_the_update_to_the_adept/)

Ploopy's response changes the weight of the story. The company says it is aware of issues its supporters have had with shipped bearings, yet gives no indication in that exchange of a revised bearing material for the A+.[5](https://www.reddit.com/r/ploopy/comments/1vo4y4r/this_is_the_a_trackball_the_update_to_the_adept/) The weakness therefore sits in an interesting place: publicly discussed, acknowledged by the maker and attached to a component whose specification and mounting method are also public.

Open hardware has done nothing magical to the bearing itself. What it has changed is the distance between “this feels rough” and a useful description of the part that may need attention.

## Mods survive

The other half of the launch conversation is easier to miss. Ploopy kept the bearing-mount geometry stable enough that modifications built around the Adept mount can carry over when their attachment depends only on that interface.[5](https://www.reddit.com/r/ploopy/comments/1vo4y4r/this_is_the_a_trackball_the_update_to_the_adept/)

> Adept → A+
> **Change the product without breaking every attachment**
> - The A+ adds two to the Adept’s six.: 8 buttons
> - Two buttons also become programmable rotary controls.: 2 knobs
> - Ploopy confirms that the bearing-mount design is retained.: Same mount
> - Mods that plug into that mount can carry over to the A+.: Mods survive
> Sources: Ploopy Blog, A+ repository and Ploopy responses on r/ploopy.

The compatibility at stake is tiny, closer to preserving a bolt pattern than inventing a universal standard, and its modest scale is exactly what makes it useful. A stable connector, screw spacing or bearing seat lets old parts and old knowledge survive a redesign; change the interface for cosmetic reasons and the surrounding ecosystem has to do its work again.

The A+ changes plenty elsewhere. Ploopy moved from six buttons to eight, turned two of them into programmable knobs, added the wrist rest, layers, gestures and on-device configuration while retaining the PMW-3360 sensor, QMK and VIA support.[1](https://blog.ploopy.co/the-aplus-is-finally-here-499) The bearing mount sits on the quieter side of that ledger, where continuity has more value than novelty.

## Open it later

One line in the assembly instructions says more about serviceability than a page of slogans. When builders apply the friction pads underneath the case, Ploopy tells them to keep the screw holes clear because covering those holes would make a later opening more difficult.[3](https://github.com/ploopyco/aplus-trackball/blob/cef2e28abe79f6dec1dda76f80ee98e31b48ae60/docs/assembly-instructions.md)

That instruction costs nothing in materials; it simply treats a future disassembly as normal enough to plan around. The same attitude appears in the files surrounding the product, where the repository includes STEP and STL geometry, native Altium electronics sources, a schematic PDF, the shipping UF2 firmware and directions to the QMK source.[2](https://github.com/ploopyco/aplus-trackball/tree/cef2e28abe79f6dec1dda76f80ee98e31b48ae60)

The mechanical README also explains an unusual packaging choice. All plastic bodies live together in a single STEP/STL so their assembly positions and clearances remain visible, after which the person printing them can split the bodies in a slicer.[2](https://github.com/ploopyco/aplus-trackball/tree/cef2e28abe79f6dec1dda76f80ee98e31b48ae60) Hardware uses the strongly reciprocal CERN-OHL-S v2 licence and firmware uses GPLv3, so the source release covers more than a decorative shell.

Liliputing's launch coverage called out the same combination of 3D-printed construction and published hardware and firmware files.[6](https://liliputing.com/lilbits-ploopys-a-trackball-has-eight-buttons-two-are-also-dials-xteink-x4-discontinued-and-more/) Looking through the repository makes the practical benefit less abstract: the files describe how a cheap wear component sits inside the object and how someone can get back to it later.

## Hard parts remain

A named bearing can still be badly made, disappear from stock or arrive with tolerances that feel wrong in this particular mount. The PMW-3360 optical sensor remains an industrial component produced elsewhere, and recreating a populated PCB from native Altium files requires considerably more equipment and skill than swapping three bearings.[4](https://github.com/ploopyco/aplus-trackball/blob/cef2e28abe79f6dec1dda76f80ee98e31b48ae60/docs/appendices/hardware.md)

Ploopy says as much in its hardware guide, warning scratch builders that self-sourced parts must meet the listed critical dimensions or the result may fit poorly.[4](https://github.com/ploopyco/aplus-trackball/blob/cef2e28abe79f6dec1dda76f80ee98e31b48ae60/docs/appendices/hardware.md) Publishing the specification removes one barrier while sourcing, soldering and manufacturing remain very real jobs.

This is why the A+ bearing story is more useful than a blanket claim of repairability. Owners have a standard part number, dimensions, mechanical access and published geometry, while people willing to go further can modify the shell or substitute another bearing system entirely.

## Useful inheritance

Ploopy could have redesigned the mount and left the Adept community with another round of adapters. Instead, the A+ keeps an interface that already has both history and baggage, including complaints about the shipped bearings and modifications intended to replace the way the ball is supported.[5](https://www.reddit.com/r/ploopy/comments/1vo4y4r/this_is_the_a_trackball_the_update_to_the_adept/)

There is no tidy victory here. A next-generation product carrying a known annoyance forward deserves scrutiny, especially when the maker already knows about it; at the same time, preserving the interface gives owners a route around that annoyance which would disappear in a sealed, newly incompatible redesign.

The bearing is a six-millimetre component. The interesting engineering decision is larger: Ploopy changed the trackball while leaving one useful point of attachment alone, allowing the problem, the documentation and the community's accumulated fixes to remain legible across generations.

## References

1. [Ploopy Blog, The A+ is finally here](https://blog.ploopy.co/the-aplus-is-finally-here-499)
2. [Ploopy, A+ Trackball repository at commit cef2e28](https://github.com/ploopyco/aplus-trackball/tree/cef2e28abe79f6dec1dda76f80ee98e31b48ae60)
3. [Ploopy A+, assembly instructions](https://github.com/ploopyco/aplus-trackball/blob/cef2e28abe79f6dec1dda76f80ee98e31b48ae60/docs/assembly-instructions.md)
4. [Ploopy A+, hardware specifications](https://github.com/ploopyco/aplus-trackball/blob/cef2e28abe79f6dec1dda76f80ee98e31b48ae60/docs/appendices/hardware.md)
5. [Ploopy, A+ launch thread on Reddit](https://www.reddit.com/r/ploopy/comments/1vo4y4r/this_is_the_a_trackball_the_update_to_the_adept/)
6. [Liliputing, Ploopy’s A+ trackball has eight buttons](https://liliputing.com/lilbits-ploopys-a-trackball-has-eight-buttons-two-are-also-dials-xteink-x4-discontinued-and-more/)