geekhack Community > Ergonomics
The PalmPuk (with MS Paint graphics)
TheSoulhunter:
--- Quote from: vvp on Sat, 30 May 2026, 09:36:05 ---But if you are lazy to move your hands around then you can also get a keyboard which does not require any palm movement while typing, like e.g. K80CS: https://deskthority.net/viewtopic.php?p=250605#p250605
--- End quote ---
Com'on, It's no about laziness, but ergonomics...
Hovering your hands over something for 6, 8, 10 hours a day, can be straining and lead to problems.
That said... Nice project! Still got the original ErgoDox (from the GB here) sitting in my collection.
Also plan to test one of these Cyborg keypads soon...
Still, this is about a palm rest. One that lets your palms slide in all directions slightly.
Because stretching your fingers is usually not enough to reach all of Num-row (from Home-row).
The Puk would also work for split-ergo boards like the one you made. It's just a different form of palm-rest.
vvp:
--- Quote from: TheSoulhunter on Sun, 31 May 2026, 09:57:47 ---The goal is to be able to slide your palm about 1 Inch in all directions...
--- End quote ---
If that is the goal then the lower part must be bigger by 1 inch in all directions compared to the upper part. The pictures do not indicate that at all.
Also the picture indicates that the ball sits in the upper bearing depression:
1) if the depression is simple spherical cutout then you will get sliding friction there and it is likely to be too much for smooth motion (even if it is made from a low friction material like e.g. teflon)
2) if the depression is a groove (shown from the direction of the groove ... therefore seen on the picture as a simple spherical cutout) then it will allow easy movement only in one direction (the direction of the groove)
If you want to have a friction less feeling with balls then the balls must be able to move as well. E.g. to move the pad to the right by one inch the ball must be able to move to the right by half an inch! This is true for any direction.
You do not have any indication in your pictures that you allow for this.
Look .e.g. at this exploded view of a linear bearing:
Notice that the bearing balls are there in "squished" loops. The balls mus be in loops since one side of the loop provides the return path for the moving balls. The other side of the loop actually is the working area. This is the area where balls provide friction less movement between the carriage a the rail. They provide the friction less movement by rolling between the rail and the carriage surface. But because of this rolling they are also moving along the loop. Therefore they need the return path. The balls are exiting the working area of the loop ... returning through the return path and entering the working area on the other side.
Balls move through the working area without friction since they are rolling. This is also the area where the balls are under load (possibly high forces between carriage and rail). The balls are not moving without friction in the return path. But the friction is very low there since there is no load on the balls.
Your design does not address the moving ball problem at all. That is the reason I pointed out other options (magnetic levitation, ...).
Findecanor:
Interesting, I have previously seen sliding palm rests of plastic/foam with teflon pads underneath. A premium variant of that concept would be something.
I have also had a pair of "ErgoRest": rests on mechanical arms clamped to the desk's edge, that allowed some movement. However, if you stretched the linkages too far, they instead provided resistant to sideways movement, so I found them to be more of a nuisance than help.
I think I had found them at a thrift store, and gave them away to a board member.
TheSoulhunter:
--- Quote from: vvp on Mon, 01 June 2026, 02:19:56 ---If that is the goal then the lower part must be bigger by 1 inch in all directions compared to the upper part.
The pictures do not indicate that at all.
--- End quote ---
The gap left and right between upper and lower part was supposed to suggest that.
But you are right, I should have drawn the gap in grey like this ...
In the 1st and 2nd version I did it right...
No idea why I turned the area blue in the third one ^^;
--- Quote from: vvp on Mon, 01 June 2026, 02:19:56 ---Also the picture indicates that the ball sits in the upper bearing depression:
1) if the depression is simple spherical cutout then you will get sliding friction there and it is likely to be too much for smooth motion (even if it is made from a low friction material like e.g. teflon)
2) if the depression is a groove (shown from the direction of the groove ... therefore seen on the picture as a simple spherical cutout) then it will allow easy movement only in one direction (the direction of the groove)
--- End quote ---
The cutout in my drawing is cylindrical, and supposed to hold split spherical bearing seats...
This way the ball wont ride on the base material, and we wont need super precise spherical cutouts.
From what I remember, these split seats also allow adjustment of the friction as they are set in a thread.
But it was a long ago I used these the last time, so I could be wrong here. Wouldn't that allow for smooth motion?
TheSoulhunter:
--- Quote from: Findecanor on Mon, 01 June 2026, 05:24:46 ---I have also had a pair of "ErgoRest": rests on mechanical arms clamped to the desk's edge...
--- End quote ---
You mean these? :D
I used them for about a decade...
Finally the pivot-joints got too wobbly and I got rid of them.
I really liked them for use in the "wide stance" (mouse + left side pad, ie. while gaming).
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