Grip Modification: Optical Trackball Improvement

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windexlight

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Aug 5, 2011, 1:58:31 AM8/5/11
to alphagrip
Hello all,

I've been using my Grip for several months now primarily for gaming.
Initially, I was worried about the trackball being restrictive as a
replacement for a mouse, particularly in games where pointer control
is crucial for camera movement. I needn't have worried, as it's
turned out to be a totally acceptable alternative, and I don't find
myself missing the mouse when in game. That said, I have been
noticing for a while that the trackball will on occasion become
"sticky", with smooth movement being impaired by hitches that
significantly reduce the overall feel of control. Opening up the
trackball for cleaning helps, but over time, the problem has become
more pronounced and more frequent.

A few days ago, I decided to try to do something about it. The
trackball itself rests on three contact points consisting of 1/8"
diameter metal balls (much like BBs) that snap-fit into plastic
bosses. These can be easily popped out, though putting them back in
without dropping them into the inside depths of the assembly is
somewhat troublesome (tweezers are helpful), and care must be taken if
one wishes to avoid removing the 8 screws necessary to open the case.
Upon close inspection, it was clear that the metal balls had suffered
significant corrosion over time (likely due to contamination with
finger oils), and that this had to be the source of the reduction in
performance. I assume these balls are a steel alloy of some kind, but
they must be a lower grade to have corroded within only a few months.
After an attempted cleaning to no avail, I decided to look for some
replacements.

Both MSC and McMaster-Carr are good sources for such things. I wanted
something that would hold up better over time, and generally perform
better. PTFE (Teflon) was the first material that came to mind, due
to its low coefficient of friction and known use as a contact material
on many trackballs (and mouse feet). To stick with the original
design of a metallic contact point, I thought 316 stainless would be a
good choice due to its high corrosion resistance. McMaster-Carr
stocks both (MSC has 316 stainless, but I couldn't find PTFE):

http://www.mcmaster.com/#ptfe-balls/=dhcvre
http://www.mcmaster.com/#type-316-stainless-steel-balls/=dhcxkc

Minimum order quantity is 100, but they're both cheap, so I picked up
a pack of each (I'll have plenty of extras, at least). After popping
in some new PTFE balls, I must say the trackball feels better than
ever. Only time will tell how they'll hold up, but I expect they'll
last much better (and be easier to clean) than the metal balls that
shipped with the Grip. I haven't tried the 316 stainless yet. It is
of course less likely to wear over time, but I almost worry about it
wearing the trackball, which is harder to replace.

If anyone else has suggestions for alternate materials or sources,
feel free to share.

Sam
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