The palm loop measurement tool is useful for gathering two of the three measurements necessary for designing a good fitting palm loop.
To properly measure for a palm loop, you want to ensure that the user’s palm is relaxed and lightly cupped:
It’s easier to ensure that the user’s palm is relaxed if it’s not lying flat on a surface.
The palm loop measurement tool comes in 3 parts – 2 fences and a crossbar. One fence slides into the other:
The male and female parts are designed to have some resistance. You should be able to push them together without too much pressure but when you hold one end up (in this case the red end), the other end (blue) should remain in place and not simply slide off. If there is too much resistance, take a small file and widen the hole in the female part. If it slides too easily, take a file and “gouge” the slider on each side – that should produce some additional resistance.
These two fences will be used to measure the width of the palm, which becomes the “length” of the palm loop. Slide the two fences together slowly until they just touch the outside of the palm:
Ensure that the user’s hand is still comfortably cupped. There should be some space between the center of the underside of the user’s palm and the slider:
Now slide the crossbar into the lowest hole so that the crossbar clears the back of the user’s hand:
The holes in the fences are 5 mm apart. The lowest hole is 15 mm above the platform:
If the bar is sitting directly against the back of the user’s palm, as in the picture above, add a few millimeters to the hole height. In this case the “height” measurement of the palm loop would be 35 mm + 2 mm = 37 mm.
The final measurement is the “width” of the palm loop. Take a metric ruler and measure the distance between the first knuckle of the pointer finger and the start of the thumb webbing:
The wider the palm loop, the more stable it will be but don’t set the width measurement any larger than this value or it is likely to cause discomfort.
The following video shows how to use the palm loop measurement tool:
The STL files for printing the palm loop measurement tool are available here.