Contour Design Perfit mouse - front

The left button on this mouse has been modified, using a Saia-Burgess low force microswitch (part # G3M1T1PUL).

The activation force on this switch is 12 cN - one quarter that of the microswitch it replaces.

I discuss the properties of this switch in considerable detail on my page about keyswitches.

The nut on the top of the actuator acts as a simple pressure diffuser.

During operation the index finger rests on the switch casing to the right of this button - and it rolls to the left to press the switch.

The original left button is held in the up position by a screw inserted into its hinge. This screw is visible in the first two photos.

I have previously performed microswitch surgery on a number of my earlier mice, usually inserting lever microswitches. However, this is the first time I have used an external microswitch.

Contour Design Perfit mouse - plan

Contour Design Perfit mouse - interior

To provide variety, I also use a 3M Renassiance optical mouse.

3M Renassiance Mouse

This mouse has an unusual design - and looks more like a joystick than a mouse.

The mouse's main features are:

• Does not involve use of the fingers;
• Forearm remains relatively supinated;
• Arm does not contact the surface at all;
• Mouse motion is activated primarily by shoulder muscles;

The main idea behind the design appears to be a sensible one.

There are a few problems - in particular:

• The little finger side of the hand is subjected to excessive force during use;
• I can't easily modify them microswitches of this mouse;
• Mouse is not wireless;

The second problem is also a bit of an issue for me.

The mice pictured above both lift the forearm off the work surface.

The idea is to allow the mouse to be controlled by muscles far away from the hand - on the grounds that these muscles are less prone to over-use injury.

There is a price for doing this - mouse accuracty and sensitivity is reduced, and the shoulder and upper arm are stressed more. However mouse-related forearm stress does appear to be reduced by this approach.

Microsoft ergonomic optical mouse

I also use this mouse, which I operate with my left hand. It is not a terribly satisfactory device.

Button activation forces

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