In praise of thumb-operated optical trackballs with scroll wheels - and some warnings about the serious ergonomic problems of mice  . . . and (maybe) how to fix a problem with the Logitech M570 trackball which results in limited cursor movement to the left

Robin Whittle Last update 27 October 2020


Also in this directory:
Back to the main First Principles site.

2020-10-27 Oooops and a few ideas

On 2018-03-14 I added a section here titled:

2018-03-14 Fixing the focal plane problem with two M570 trackballs

Here is a complete retraction of what I wrote then. I wrote about it to a Logitech support forum, which no longer seems to exist (URL)

I found that left-right thumb movement moved the cursor to the right OK, but not so much to the left, only when I used little pressure.  I assumed that this was due to the ball being too far away from the focal plane of the sensor when I pressed lightly, and that this somehow upset the system, with pressing the ball more firmly causing the ball to be a little closer, in focus and so causing the sensor to work properly.

In October 2020 I realised this explanation was 100% wrong.   Sorry about this!

The real explanation seems to be that the friction from my thumb to the ball was inadequate when moving my thumb to the left, causing the ball not to move so much.  Extra pressure fixed this.  However, the problem was also fixed, with light pressure, by rubbing my thumb on a wax candle.

With care, I could see that without the wax, and with light pressure, the ball was not moving entirely with my thumb in the left direction.

My fix, based on the original hypothesis, was to use a hot air gun and press the sapphire (I guess) sphere closest to me a fraction of a millimetre into its plastic housing, to move the ball closer to the focal plane.

For a while I thought this worked.  However, in the end, I found that my thumb was having greater difficulty in general moving the ball.  My workaround was a blob of candle wax on the side of the case, just to the left of where my palm rests.   I would rub my thumb on this and all would be well for a while.

Then I reconsidered and noticed the ball was not moving with my thumb properly, and that there was no reason to suspect a problem with the sensor at all.

I then thought about how I moved the near sapphire ball into the case.  This meant that the triangle of points which holds the ball was now a little wider, with the ball sitting deeper within the triangle, and with (for any mass of the ball plus thumb pressure) a greater force on each of the balls.

So I used the hot air gun to move the ball back - a far from exact operation.  Maybe I moved it a little further to the ball than it was originally.  This would reduce the size of the triangle and so reduce the force on each of the balls.  This would reduce the friction on the balls, which would mean that I could move the ball more freely for a given light force, and a given, perhaps rather low (with dry skin, no wax etc.) finger friction.

Anyway, it is working like a charm now.  

If I moved the ball further in than it was originally and if (as I predict) this reduces friction and if as seems to be the case, the trackball is working better than in its original state, then maybe, via a very circuitous path, I discovered a totally different, and opposite, fix for my original problem.  

This is highly speculative - and since my last hypothesis was completely wrong, all the moreso.

If you have trouble with the trackball, it might be dust in the cavity where the laser and lens is, with fluff over the lens.  Perhaps a vacuum cleaner is a good way of getting rid of this, or some tweezers, or perhaps a little tissue paper with isopropyl alcohol.

2011-05-05 No more cable-connected Logitech trackballs

Logitech no longer make a cord-connected thumb operated trackball.

I have been using their thumb-operated trackballs since 1990 - the one with a grey ball and rollers "Trackman Mouse T-PA1-9MD".  In March 2018 I found only these photos of it: . It is interesting to see that such a significant piece of technology, from pre-Internet days (for all but those in academia) is so poorly documented 21 years later.

Update October 2020, now 30 years later, I found a photo of one on eBay, where it was described as being from 1989, and was selling for about USD$58:

They still make a wireless one, which requires a little USB plug receiver - and batteries, and synchronisation with the receiver.  This is the Wireless Trackball M570.

Perhaps you may like to add your thoughts to this discussion of the demise of these fine devices:

Fortunately there are plenty of the last wired model around, including on eBay: "Logitech Trackman Wheel".  Must these excellent devices go the way of airships and electronics-free cars?

Logitech stopped making wired versions of their excellent thumb-operated trackballs in 2011!

Back to the 2000 version of this page . . .

The computer mouse is an awkward, stressful, RSI-causing monster.  So is the QWERTY keyboard - which has keys laid out specifically to slow typists, in order to reduce the jamming of hammers in early mechanical typewriters.  Unfortunately, the alternatives to the QWERTY keyboard are unlikely to be widely adopted because they are either very different from a keyboard, or involve a different (Dvorak) arrangement of keys which is impractical to learn without going totally cold-turkey on QWERTY.

Fortunately, changing from a mouse to a better alternative is easy.

This page is devoted to what I believe is by far the best approach to pointing devices for general use - the Logitech TrackMan Marble Wheel. (The Marble Wheel is for PS-2 and USB interfacing, and works with the Macintosh.  I also use the TrackMan Marble + which is PS-2 and serial.  The earlier TrackMan Marble does not have the scroll wheel.)    The right hand must be used - which may be a problem for left-handers.  It may not be as good as a mouse for drawing motions - but a mouse is lousy for those anyway.  Apart from these constraints, I believe that anyone currently using a mouse would be much happier using a Trackman Marble Wheel, that their productivity would be improved and that the risk of RSI would be greatly diminished.

The problems with mice

A technical journalist friend of mine had severe shoulder pain from using his mouse (a Mac mouse) - to the point of having elaborate exercise machines in his office so he could perform the physiotherapy exercises he needed.  He had to keep working, so he learned to use the mouse in the other hand!

It seems that it is very easy to learn what a mouse does - children do it in a minute or two.  It seems that using a thumb-operated trackball takes a little longer - but it is not a hard device to use, and the RSI and productivity benefits make it well worthwhile.

Pointer devices other than optical thumb trackballs or mice


The Logitech Trackman Marble +

Logitech make a number of trackballs, not all of them using optical sensing.  See:

The one I currently use is the Trackman Marble Wheel.

The advantages of this over all other systems (apart perhaps from other Logitech optical trackballs) include: The disadvantages include:

Care and feeding of the Logitech Marble +

When the Marble is first purchased, the ball does not roll as freely as is it is meant to.  This could be a significant marketing problem, as people try it out in the shop and find the ball does not move freely.

The solution is simple:

"Oiling" the ball

The ball will run perfectly freely when it is has a bit of naturally occurring skin oil over its surface.  This is not visible, but it makes all the difference.

When the trackball is manufactured, or cleaned (for instance taken out and cleaned with soapy water or alcohol) this oil is removed, and the ball will be quite stiff, rather than running freely over its bearings.

Oiling the ball in situ:

Run the palm of your hand over the ball to move it in all directions.  There is no need to press hard – just do it for a few minutes until the ball becomes so free you can give it a flick and it will continue to spin for a fraction of a second.
Oiling the ball if you have taken it out:
Simply roll the ball around in your hands.  This puts a bit of skin oil over it very quickly, so with maybe 20 seconds of this, it will be ready to roll freely.
The ball will be so free that even if you just touch the ball with your thumb, the ball will move freely.  Without this, you may find the ball sticking a little, or that its friction may cause your thumb to slide over the ball while it does not move properly.  This is not how it is supposed to be! Make sure the ball has a bit of skin-oil on it and it will move perfectly freely.

The ball is supported by three small (~1.2mm diameter) stationary spheres of a very hard material.  Previous models appeared to use synthetic ruby, but current production uses and opaque silvery glass-like material which seems to be just as durable.  Quite why a hard plastic ball should glide smoothly over three small fixed spheres is a mystery to me, but a touch of naturally occurring skin oil is essential.

If the ball is washed in alcohol - and there is typically no need to do this - then the stiff motion appears again and it is necessary to "oil" the ball, as described above.

Cleaning.  The only cleaning which should ever be required is:

That's it.  The scroll wheel uses optical sensing and should not need cleaning unless someone actually pours coffee or glue into it. It looks robust and I don't imagine it will wear out in years of normal use.  I have been using Logitech Marble optical trackballs intensively for years and have had no trouble.  They are far superior in movement to the older sea-shell-shaped light-blue ball model, or the still older grey-ball model, both of which used rollers, rather than optical sensing.

Drivers and acceleration

The stressfulness of using a mouse, or trackball, is exacerbated by the default setting of MS Windows mouse driver software which transforms tiny mouse movements into large screen movements, whilst providing little "acceleration".  In my experience the default settings for the Macintosh are much better.  X Windows mouse drivers are, in my experience, little better than the MS Windows standard drivers.  "Acceleration" involves making slow mouse movement cause moderate pointer movement, but faster mouse movement cause much greater pointer movement.  I think the default settings on the Mac have an acceleration which is a bit too high for my liking, but I believe the standard Mac mouse driver settings are a significant reason why the system remains popular.

All Logitech pointing devices come with a good driver program for Windows.  The Marble + plugs into the PS/2 mouse port, and functions like any standard mouse (although I think the scroll wheel would not function).  To use it properly, install the supplied Logitech driver software.  This creates a "mouse" item in the Control Panel (Start > Settings > Control Panel).  The only settings I alter are for the motion - to set the "Speed" to slow and the "Acceleration" to high.  (The following illustration is for an older version of the software than the current 8.50.)


This gives me really precise cursor control when I move the ball slowly.  The result, with such slow movements, is about a 1:1 relationship between ball and cursor movement on the screen - perhaps 120 pixels for a 1.5 inch movement of my thumb.  (This was for earlier software.  The exact details may be different for the Marble Wheel and 8.50 software.)  If I move the ball quickly, the acceleration factor is applied and the ball moves much further.  Unlike the super-accelerated Mac mouse settings, this does not move the cursor to the other edge of the window, but it does move it most of the way across or up and down the screen.  Unfortunately there is a limit to how fast the optics can follow the ball, so there is no point in flicking the ball very quickly.  The ball free-wheels a little, so you can give it a flick and let it roll.  Giving the ball two flicks with the thumb is far easier and quicker than moving a mouse to the edge of the mat, and then picking it up for another trip across the mat.

Alternatives to the Logitech Marble Wheel

Logitech make a Marble FX, which looks intriguing.  I haven't used it.  Perhaps the larger ball and ability to control it with thumb and index finger provides more precise control than the Marble Wheel.  Their "Marble Mouse" is not a mouse at all, and involves finger control of the ball and the thumb for the primary mouse button.  There is no scroll wheel.  I see no benefit to this over the Marble +.

Microsoft now makes a trackball called the Intellimouse Trackball:  It uses the index finger for the ball operation, the middle finger for the scroll wheel and the thumb for the primary mouse button.  It does not use optical sensing.  They also make a jumbo-sized "EasyBall" trackball for children.  (May 2000: they also make a mouse which optically tracks the table moving underneath it.  This should solve cleaning problems, but the thing still has all the ergonomic problems of mice.)

Genius make a trackball similar in layout to the pre-scroll-wheel Marble the "EasyTrak".

Other than perhaps the Marble FX, I cannot see how any of these would be superior to the Marble Wheel.  (Unless you want to use serial connections, because your computer has neither USB or PS-2.  In that case, you need to find an older Marble +.) The Marble Wheel  retains all the switch function finger actions of the standard mouse, and simply replaces the hand-arm-shoulder motion movements of the mouse with the much simpler and easier thumb movements for the trackball.

Where to buy the Marble Wheel

Logitech's site is well organised.  There are separate sections for particular countries, and an easy-to-use system for locating the nearest retail store.  I found that this did not list every retailer which actually carries Logitech gear.  In Melbourne, I know that Software Express has them.  I bought my most recent Marble Wheels from Harris Technology: .