In late 2011, I was struck by a fantastic idea: using a second CH Products DT225 trackball for scrolling. I already owned a DT225 with a USB connector and had configured it such that it could perform scrolling on Linux. But having to press the top right button with my right ring finger every time I scrolled was taking its toll on my wrist.
What if I could use a similarly large trackball to scroll with my left wrist instead? With this setup, I would move the cursor with my right hand and scroll with my left.
Coincidentally, a used DT225 with a PS/2 connector became available on eBay, and I purchased it for a good (i.e., low) price. The advantage of having two different connectors was that my Linux box recognize them as two different devices. This made configuration extremely easy—essentially following the steps here.
In /usr/share/X11/xorg.conf.d/10-evdev.conf, I added the following lines:
# - - - CH Products DT225 Trackball Settings - - -
# - - - - - by bootstrap (geekhack.org) - - - - - -
# To help readers understand the configuration better, a CH Products DT225
# trackball has buttons labeled as follows:
# A (left-large), B (left-small), C (right-large), D (right-small).
# Usage: A=normal-click B=Back C=right-click D=Forward
# Press button D (hold button while rolling trackball) to emulate
# The trackball can scroll in two-axes, unlike a typical wheel mouse.
# Adjust the settings to constrain the scroll action to vertical-axis-only
# if you prefer.
MatchProduct "Composite USB PS2 Converter USB to PS2 Adaptor"
# Physical button labels: A B C - - - - D (- = no button)
Option "ButtonMapping" "1 8 3 4 5 6 7 2"
# EmulateWheel refers to emulating a mouse wheel using trackball.
Option "EmulateWheel" "true"
Option "EmulateWheelButton" "0"
Option "ZAxisMapping" "4 5"
Option "XAxisMapping" "6 7" # Disable this for vertical-only scrolling.
At the time I purchased the second DT225, I wasn’t sure if my plan would work or if using a second trackball for scrolling only would be a longstanding solution.
Well, it’s been more than 8 months and I’m still using two trackballs on both sides of my keyboard—left and right. Occasionally, I scroll with my right trackball by pressing the top right button out of habit but overall using the left trackball for scrolling has done wonders for my right wrist pain.
However, there is one problem with the left trackball. It’s more a cosmetic issue, rather than a functional one. You see, the “used” DT225 I acquired was really “used” with some fairly deep scratches at some spots.
The left side of the device remains in very good condition:
The back of the device had residue of some sticky tape. Removing this should not be a problem.
In addition, the cable was probably rolled over on a rough surface (possibly gravel).
I had the option of replacing the trackball but the issues were:
- Finding a DT225 trackball with a PS/2 connector;
- Spending an additional $120 or so to replace a perfectly functional trackball; and
- Fixing the cosmetics of the current trackball.
As it was a cosmetic issue, I’ve been dragging my feet over the matter. However, on my most recent trip to Singapore, I found a few extra hours for myself (as opposed to business) and was fortunate to come across a hobby shop that specialises in plastic models. I purchased two items that would probably fix the cosmetics of the trackball:
1. Tamiya Epoxy Putty
This will be used to fill up the defects.
2. Humbrol Maskol
This will be used to cover the DT225 sticker on the top of the device when I paint it.
I also purchased a can of Krylon Fusion for Plastic spray paint in Satin Almond, which is close enough to the original colour of the trackball.
I already had a full can of Krylon Fusion for Plastic in Flat Black—I’ll use this on the cable.
Here’s the plan:
- Fill up all the scratches on the DT225 with the epoxy putty.
- Fill up all the scratches and other defects on the cable with the epoxy putty.
- Sand the surfaces of the DT225 and its cable.
- Cover the sticker on the DT225 with Humbrol Maskol.
- Paint the case in Satin Almond.
- Paint the cable in Flat Black.
After what I went through with the Model F, this job should be a walk in the park.