Tablet stand

[DrC]

Want to stand your tablet up at a particular angle - no problem. This tablet stand is designed to put the centre of gravity of your tablet at the same height whatever angle you put it in at. As a result there is no tendency for it to fall forwards or backwards. Put it in at any angle and it stays put.

The design starts with a block with the front window cut out. The block is then profiled to provide the back support - a quarter of a cylinder with a projecting shelf behind to stop the tablet falling off when horizontal - and a parabolic front face so that when the tablet is put on the back support touching the front face the centre of gravity is very nearly the same height as when the tablet is horizontal or vertical.

Finally, the two side cheeks are added to locate the tablet between what is left of the front face either side of the window cut out.

The design is specific to the tablet. The reference centre of gravity height is the height of the centre of the tablet when vertical and it rests at this height on the quarter cylinder when horizontal. The design compensates for the thickness the tablet below the centre of gravity (reducing the radius of the cylinder) and the thickness above the centre of gravity where it meets the front face (affecting the parabola).

The example is for a mid-sized tablet standing in portrait orientation. Dimensions matter so you will need to change some numbers - more on that later.

Meanwhile take a look at this and enjoy.

Unfortunately you can't just change the numbers - something in either my design or FreeCad goes totally awry if you touch it, so you need to redo each sketch and component in sequence using your own dimensions for the radius of the cylinder based on the centre of gravity modified by the thickness, the height of the centre of gravity, the width of the window you need and so on.

Meanwhile, I will try to get the techies to sort out why it breaks.

Enjoy. DrC

[kisolre]

Just a little general cleanup. But if this should be 3D printed there is too much waste in the infill/supports. IMO better do it with two flat sides with channels and a curved insert printed in vase mode.

[Shalmeneser]

The design is specific to the tablet. The reference centre of gravity height is the height of the centre of the tablet when vertical and it rests at this height on the quarter cylinder when horizontal. The design compensates for the thickness the tablet below the centre of gravity (reducing the radius of the cylinder) and the thickness above the centre of gravity where it meets the front face (affecting the parabola).

I don't understand everything. Can you give a hand-drawing sketch showing where is the tablet and its gravity center ?

[DrC]

Can you give a hand-drawing sketch showing where is the tablet and its gravity center ?

Gladly. The shaded area is the tablet in three different positions, with its centre of gravity shown by the three red dots. The blue lines are the FreeCad construction lines and the green is the outline of the solid.

The back of the tablet rests on the quarter circle of the diagram, representing a quarter of a cylinder in the solid. The front corner (or the edge of the tablet in the solid form) touches the parabolic shape, keeping its centre of gravity on the horizontal blue line.

The tablet extends out of the diagram an equal distance from the centre of gravity.

it works because the centre of gravity is always higher if the front of the tablet doesn't touch the parabolic face, so it always does. The parabolic face means it can't go any lower so it always stays there.

Cheers

DrC

[Shalmeneser]

Thank you very much. I understand now.

[DrC]

Replying to Shalmeneser:

In case you teach mathematics or physics, the parabola is not an exact solution. It is the best fit I found using the FreeCad tool set.

DrC