I find myself in need of objects that can be easily laser-cut. The deskbox for the office is an example, but there are others: chairs, storage boxes, etc.
I’ve been sitting on this issue for more than a month since I moved. In a way, over a year, kind of due to lack of money. But now I have money, and I need to make my things manageable. And I need to return to the learning cycle.
So far most of the pieces I’ve cut have been 0.01 m², with the exception of that one that was about 0.1 m² and didn’t turn out that well. The deskbox is about 1 m²; the bedbox is about 10 m². So I should make some smaller things first.
At the 0.02 m² level, I could benefit immediately from a draining rack for cutlery, maybe with a 100 mm x 200 mm bottom and 150 mm walls, and bottom hole diameter of no more than 8 mm so the steak-knife tips can’t poke through very far. Also, for cleanability, it would be nice for the bottom to be as thin as possible and have relatively round holes, and it would be nice for the joints to have some kind of inside radius or at least be relatively rounded for the same reason, and to be connected in ways that don’t leave cracks for mold to grow in.
This couldn’t be made of MDF; acrylic and HIPS are options. (Max58 has clear, black, and white acrylic in 2.4, 3, 4, 5, and 8 mm, and HIPS in 1 mm.) Both acrylic and HIPS can be solvent-welded with acetone or MEK (and maybe ethyl acetate, I’d have to try it) but resist alcohol. Heat welding and caulking with silicone are plausible alternatives.
There is a good introduction to solvent welding on the NerfHaven forum. It has a short list of acetone-resistant plastics: Delrin, UHMWPE, nylon, Teflon. Nylon and Teflon resist every solvent on the list, and I suppose epoxy would too. Paint thinner may be my best bet in Argentina.
The bottom holes can be relatively infrequent; they don’t have to fill most of the bottom. The bottom will bow downward with the weight of the cutlery, so I need a bottom hole in the middle, at least.
HIPS supposedly has 40% elongation at break, so I should be able to curve it into really ridiculously curvy shapes, to the point of origami. (The ratio of its 32 MPa UTS to its 1.9 GPa tensile modulus, however, suggests more like 1.7% elongation.) Maybe actually the best approach would be to cut some darts into the edge of a single piece and then weld them shut to make a curvy shape.
PMMA, by contrast, only has 4% elongation at break, which beats the hell out of MDF but isn’t very much. And I’m more sanguine about its food safety. So the 2.4 mm PMMA could presumably be compressed 4% on its inner face and stretched 4% on its outer face at 1.2 mm, giving a curve radius of 1.2 mm/4% = 30 mm. This rather implausible result suggests that I should be able to bend it into 600mℓ bottles. I think they would be fairly prone to exploding, but maybe they could work.
PET panes of 0.3mm are available from Maderera Gascón at a lower price than acrylic. These are AR$115 for 1×2 m.
The whole cutlery drainer would be (+ (* 2 200 150) (* 2 100 150) (* 200 100)) = 110000 mm² or 0.11 m². If I make it as a box from separate pieces, the biggest separate pieces are the 200×150 sides, which are 0.03 m², which is the right order of magnitude for this project.
The simplest possibly usable design would be a box with some hooks on the side, with a few tabs to keep the pieces aligned while I glue them: (+ (* 2 2 (+ 200 150 100 150)) (* 2 (+ 200 100))) = 3000 mm of box edges to cut, plus the tabs, the hooks, and the drainage hole. Maybe 2 minutes of cutting.
Or maybe two 100mm-radius approximate semicircles (.0314 m² each) plus a 100mm×314mm rectangle (also 0.0314 m²) to bend into a semicircle, with a drainage hole in the middle, a couple of tabs to hold it together for gluing, and a couple of hooks on the side. That’s (+ (* 2 (+ 100 314 200 314))) = 1856 mm of edges to cut, plus the drainage hole and the hooks.
Or maybe both. Or more possibilities. If I use 3mm acrylic, it should be dimensionally compatible with MDF Heckballs, but awesomely transparent and stuff. If the acrylic sheet is 600×400 (.24 m²) I have room for about 8 pieces of this size, so basically both cutlery drainers and not much else.
A 600×400 mm sheet of acrylic might cost AR$300 or AR$400. If cutting still costs AR$0.40 per second and cutting is 24 mm per second plus 60 ms per vertex, we have only about 90 seconds of cutting for the semicircle thing and another 200 seconds of cutting for the box (99% edge, 1% vertex), totalling like 300 seconds and AR$120. This suggests that the quality of the product could be improved dramatically at minimal extra cost; doubling the cut time by using 100× as many vertices would be a minimal problem, for example, and there’s plenty of time to engrave surfaces and scallop edges and stuff.
While I’m at it maybe I should make some bowls or something. PMMA is about 1.2 g/cc, so 8mm PMMA should weigh almost 1g/cm². So an 0.03 m² bowl (crudely: 0.01 m² of base, plus four sides of 0.005 m² each — 100 mm × 100 mm × 50 mm) would be 300 g.
I’ve moved again! Now I have no housewares.
I need fans, and I have motors and power supplies. A pinwheel-like structure should be easy to cut out of thin HIPS; also I should be able to assemble something out of sheets of acrylic or even MDF.
I now need an entire draining rack.
I’d like to make some IQLights. These can be laser-cut out of HIPS as well, I think.
I’d like a dehydrator, an apparatus that runs heated air through a serpentine airflow with food or other things on shelves. I’d like a dehydrator for food, a dehydrator for garbage (so the garbage doesn’t become food), and a dehydrator for laundry, although that may be aiming a bit high.
I need chairs. A relatively small amount of PMMA should suffice to make a sittable chair, but it will be somewhat fragile, and potentially cut you if it breaks.
Sheets of PMMA should work adequately as cutting boards.