baffled by ball..

[nourathar]

Hi,

after I got myself a CST L-trac trackball, I picked up a 57.2mm monochrome yellow snookerball for better looks and to improve smoothness. It looks good, fits as expected and mechanically it moves more smoothly than the stock ball. But it doesn't track properly at all; cursor movement is slow and erratic, often much faster in one direction than the other. Such problems instantly vanish when I pop the stock ball back in, so there is nothing wrong with my unit.

Since this is a very common mod I am a bit baffled by this. I have two hypotheses:

- ball surface is too smooth, I can imagine the optical tracking needs a minimum of optical flow; i applied some grease to make the surface less uniform, but that makes no difference.

- can the colour be wrong ? I don't know at what wavelength the laser tracking works, but perhaps my nice new ball is too reflective or unreflective at that particular wavelength ? I have seen pictures of yellow pool balls in CST's before, so it would be weird ?

On the Trackballworld site they list a transparant blue ball of the right size (http://www.trackballworld.com/product200.html) as nevertheless not being compatible, so that could perhaps be for a similar reason ?

any ideas or experiences ?

[nourathar]

ok, I think I have proof..

for a project I hacked a webcam so that it sees InfraRed and I read somewhere that that is the wavelength they use in optical trackballs and mice.

So I dug it up and used it to look at the spot of IR-light caused by the laser on the ball,

first the stock, black ball that comes with it:

l

and then the Ball That Baffles:



I suppose that if my cam stops seeing surface detail due to overexposure, it must be the same for that sensor ?

still mystified why this does not happen to others who did this mod..

J.

[microsoft windows]

DID YOUR ORIGINAL TRACKBALL HAVE LITTLE DOTS ON IT? A LOT OF LASER TRACKBALLS NEED THE DOTTED BALLS IN ORDER TO TRACK THEIR MOTION WITH THE SENSOR.

IF YOU GET A MECHANICAL TRACKBALL WITH ROLLERS I THINK THIS YELLOW BALL WOULD WORK BETTER.

[Wildcard]

Yeah CST doesn't use dots on their trackballs MS. I'm wondering if this snooker ball has a clear acrylic coating on the outside of the standard polyester resin that's messing with the optics. I use black/white cue balls that are polyester resin but polished. I've also used a #1 standard billiards ball which is yellow and also worked fine. These optics are focused to track surface imperfections by measuring the light output, however as you indicated the surface appears to be too reflective to sense these bumps. I know you'd probably hate to ruin the shine on this ball, but perhaps use something with a very very fine grit to dull the surface a bit?

Or I'd just try another cue ball or try a higher quality standard billiards ball that is possibly all polyester resin and possibly less reflective on the surface.

[nourathar]

Hi wildcard,

yes, your suggestion makes sense so just now I made the ball a lot less shiny by rubbing it in very fine sanding paper.
I tried it and it makes no difference whatsoever, unfortunately.

And the yellow ball I got is supposed to be an aramith ball: perhaps their cue balls are higher quality, but I understood that their balls are the best available more or less ?
For now I'm happy with the stock ball and at some point I will get a cue ball or something more adventurous when I see sth. and try again...

thanks,

J.