Is my thumb just too smooth ;)

Hi,

Often, when I attempt to move the trackball (mines a red one) with my thumb, my thumb just moves over the ball, and ball doesn’t move. My thumbs not grippy enough!

Is this a common problem, is there something I can do about this?

Thanks!

Matt

You can try to clean the module.

Furthermore, you can try the Glossy Trackball Ball - Ultimate Hacking Keyboard, which may improve the matters (or not).

Hi there,

The ball should always move when moving it with a thumb. I can’t recall a case like yours. Feel free to make a video and share it with us.

The module cleaning instructions might help.

Hi,

I did try cleaning it, it still happens though, although not all the time, maybe 10% of the time. As an experiment, if I use the bottom of my finger, it’s fine, and the ball will always move, but with the side of my thumb, it just doesn’t work as reliably.

I’m not too bothered really, since I still use a mouse most of the time, it’s just something that I thought I’d share in case others had had this (sounds like it is just me)

(If there is a ball that’s more grippy, would be interested in that)

Well, the ball slides over three other small smooth bearing balls, so following factors come into play:

  • weight of the ball - the steel ball is very prone to this problem, as the combination of rough surface and high weight creates a lot of friction between the ball and the bearings
  • shape - if the ball is not perfectly spherical, it will tend to get stuck in one position, leading to fingers slipping on the surface.
  • surface roughness - smoother ball will have much lower stiction and will glide easily over the bearings.

I.e., this is not just about grip of your finger against the surface of the ball. More about the ratio of grip on your finger and friction/stiction against the bearings. Fingers tend to have a relatively good grip against glossy surfaces, while smooth/glossy surfaces have low friction against the bearings.

The glossy ball may be worth a try because of its smooth surface. On the other hand it is heavy and prototypes had some problems with shape. No idea if that got sorted out before production. So it may or may not work.