A way to lean the screen and hold in place will be required for sure.
How about drop down/fold out leg/legs at the back of the screen cover to help support the LCD frame.
Either a wide one in the middle or 2 small on the edge of frame.
Notches for this leg/legs could be incorporated in case to lock and hold into place,
When titled it would hold firm and hinge is not bearing all the force/weight.
You could then possibly use a less complicated hinge design.
As soon as the screen is tilted up, leg will drop find a Notch, and you can adjust to required viewing angle with other notches.
Latest prototype, the buttons are too flimsy, some tolerances are too tight, and others too loose. I think we will keep assembly simple and do away with the buttons.
The buttons were also poorly assembled, and the lower casing is wider by 4mm on purpose.
One of our engineers said: “It’s a beautiful case, but the buttons are terrible. Maybe we should have a daughter board with more widely-spaced buttons mounted on top of the case.”
Our supplier said (rough translation from chinese): “Those buttons are really too small to glue together. If you’re going to make thousands of those little things, the workers will curse you to death!”
Options:
(1) Wide cut-out as per previous prototypes for the buttons, requires a narrower lower case; some adjustment to maintain plastic strength is necessary.
(2) Mount a (new) daughter board with widely spaced buttons on case top, maintain current lower case width.
Looks like a real mini-computer now. Just a few things:
If you forget to attach the FPC cables before glueing the LCD panel into its frame, you’re done. I will cut a wider “thumb slot” into the frame to make it more forgiving.
I’m thinking of having the captain slot into the case from the bottom, since once you locktite the LCD frame in place, you can’t open the device from the top anymore. So only disassembly from
the bottom, like a clamshell laptop is possible.
Disassembly from the bottom will make swapping the battery and SSD much quicker, once fully assembled.
Maybe installing something like Lakka or LibreELEC to run some retro games would be the objective.
Been looking at some blindnuts, the external diameter alone is 5.38mm - a tad too large for that acrylic part.
The spring / washer isn’t so much of an issue though - will attempt those first. Likely the spring will add sufficient tension to the nut, so it doesn’t come loose as easily.
Finally figured out how to design external buttons that are simple to manufacture, assemble, and work properly. No need for the use of springs or other complicated mechanisms. Springs could be used to make the mechanism “softer”, but entirely unnecessary.
Screw - Spring - Washer - Acrylic - Acrylic - Washer - Spring - Nut
I do believe it will eventually come loose (the nut will probably loosen due to vibration, wear, etc), so some removable locktite is probably necessary for longterm usage. However, from what I found just now, is that at first it starts of stiff, then after some time it finds “an equilibrium”, which is looser, but this does not change afterward. The hinge tension seems stable.
The “equilibrium tension” is sufficient to maintain the screen at any angle.
Ahh this is informative, I understand how it works now. Apparently, there’s some debate as to its effectiveness, also it should not be used together with a conventional washer.
Mmm probably an even better solution would be to use a smooth shaft to isolate the bolted components from the hinge rotation. And add some toothed washers (or maybe even Kep Nuts, if I can find any) to keep the bolts in place. Will need a bigger hinge though…
Update: Okay it works just fine without the conventional washers. So its Screw — Lock Washer — Acrylic — Acrylic — Lock Washer — Nut. You have to screw it even tighter to begin with (probably biting into the acrylic), then wiggle the hinge say a 100 times, and the tension becomes stable. (It makes noise without the conventional washers though!)
Just thinking out loud.
What about…
Screw- external star lock washer- Stationary Acrylic- Rotating Acrylic- nylon washer-metal washer- Nut. A second nut could be used as a Jam nut to further resist spin off.
Thinking on this is, Screw resists motion because the star washer bites in to the stationary acrylic and the screw. The nylon washer against the rotating acrylic will slip with either the acrylic or the metal washer, hopefully reducing the nut from being spun off.
Everything but the metal washer and star washer could be nylon fasteners. Should be quiet.
Update: I see M2 Nyloc Nuts(nylon-insert lock nut) are available. Should completely resist spin off. So Khadas metal M2 screw and M2 Nyloc nut might be better than nylon screw and nut.
Just ordered some star-toothed washers, nylon washers, and nyloc nuts. I’m using M3 for the hinge, as M2 components are a little rarer to come by. Also the narrower M2 shaft allows more hinge-play and less support.
So for the gamepad buttons extending out of the case, I’m hoping the 6mm shaft and shorter M2 screw would reduce the play (and thus slippage) of the “plunger”.
I think the star toothed washers and nyloc should work fine. Not too sure about the nylon washer though, I used to help my friend build 3d printers that had delrin slip-and-slide components (expensive though)!
