Okay, here’s another (wow, has it really been four years…)
We’ve been slowly acquiring fish tanks. In order to make custom lids which fit each tank and allow for growing plants in them, we need little clips which can hold the lid of the tank. Most of them, we get the right size for, but there’s one tank which is a bit different.
Rather than the 5mm side walls all the rest have, this one has 4mm on the sides and back and 3mm on the front.
But hey, I have a 3d printer. This is a great chance to put it to good use!
The initial sketch
First, the initial sketch and notes on my desk:
Having a whiteboard for a desk is really quite handy at times.
Then, we move that over to FreeCAD. I’ve used it before, but never for anything at all complicated (which I suppose this isn’t either). Remembering how in the world to use CAD programs takes a minute:
Those orange dimensions there I’m particularly happy with, they’re parameterized:
So I can change any number in the sheet (and assuming it actually works), the part will just change everything to match. Pretty cool, especially since I did end up needing a couple of different sizes for the different wall thicknesses.
You might notice the 4.02 mm for the middle number there. That’s because the actual forumla is 1.005 * <<params>>.glass_thickness. This gives the pieces just a little bit of room (half a percent) of tolerance to slide on. That percent is completely a guess, but seems to be working so far, so we’ll take it.
Single clips
With the sketch done, all that was left was to extrude the parts in FreeCAD:
Originally, I was going to put a fillet on each of the inside corners, mostly to look nice. But it seems you cannot parameterize those. And I couldn’t get a curve based on the shape of the top surface to work. So for now, that will work.
Making corners
But that’s not all. The harder(est?) part was that we wanted a clip for each corner. And I have no idea how to do that in FreeCAD. It should be possible to create a 3mm edge and a 4mm edge and place them both in a new par in FreeCAD, then add a new piece between them, but I just could not get that to work (yet).
So instead, I jumped online to TinkerCAD, imported the two pieces, and just drew a piece between them.
It feels so hacky, but it works!
Even better? The best way I’ve found to print it?
This piece is not very friendly to printing without supports. But they’ve proven easy enough to remove, so we’ll go with it.
And the final results?
It slides on perfectly and is exactly the right depth to hold the lid.
3D printing is just so cool sometimes.
(If you’d like to download the file, here you go!)
OpenSCAD
Okay, I couldn’t leave well enough alone. Here are some versions that use OpenSCAD instead!
// How thick the glass you're fitting over is
glass_thickness = 4;
glass_tolerance = 0.05;
// How thick the lid is you're putting on top
lid_thickness = 5;
// How thick the plastic should be
piece_thickness = 2;
// How far the shelf extends inwards and then side to side
shelf_depth = 10;
shelf_width = 30;
module shelf(glass_thickness) {
// Lip over the edge
difference() {
translate([0, 0, 0])
cube([
glass_thickness + 2 * piece_thickness,
shelf_width,
lid_thickness + 2 * piece_thickness
]);
// Cut out for glass
translate([piece_thickness, 0, 0])
cube([
glass_thickness,
shelf_width,
lid_thickness + piece_thickness
]);
}
// Shelf
translate([
glass_thickness + 2 * piece_thickness,
0,
piece_thickness
])
cube([
shelf_depth,
shelf_width,
piece_thickness
]);
}
shelf(glass_thickness * (1 + glass_tolerance));
And for the corner:
// How thick the glass you're fitting over is
// These can be different for two different sides
glass_thickness_a = 4;
glass_thickness_b = 4;
glass_tolerance = 0.05;
// How thick the lid is you're putting on top
lid_thickness = 5;
// How thick the plastic should be
piece_thickness = 2;
// How large the cutout in the corner should be
corner_size = 20;
// How far the shelf extends inwards and then side to side
shelf_depth = 10;
shelf_width = 30;
module shelf(glass_thickness) {
// Lip over the edge
difference() {
translate([0, 0, 0])
cube([
glass_thickness + 2 * piece_thickness,
shelf_width,
lid_thickness + 2 * piece_thickness
]);
// Cut out for glass
translate([piece_thickness, 0, 0])
cube([
glass_thickness,
shelf_width,
lid_thickness + piece_thickness
]);
}
// Shelf
translate([
glass_thickness + 2 * piece_thickness,
0,
piece_thickness
])
cube([
shelf_depth,
shelf_width,
piece_thickness
]);
}
translate([0, corner_size, 0])
shelf(glass_thickness_a * (1 + glass_tolerance));
translate([corner_size + shelf_width, 0, 0])
rotate([0, 0, 90]) shelf(glass_thickness_a * (1 + glass_tolerance));
difference() {
translate([corner_size, corner_size, piece_thickness])
cylinder(h=piece_thickness, r=shelf_width);
translate([0, 0, piece_thickness])
cube([corner_size, corner_size, piece_thickness]);
// Going along each lip
translate([-shelf_width, -shelf_width, piece_thickness])
cube([shelf_width + glass_thickness_a + piece_thickness * 2, 3*shelf_width, piece_thickness]);
translate([-shelf_width, -shelf_width, piece_thickness])
cube([3*shelf_width, shelf_width + glass_thickness_b + piece_thickness * 2, piece_thickness]);
};
It’s even curved!
At this point, I already have the other version printed, so I’m not going to go back and make these as well… unless we get more fish tanks. 😇