Printing at large

With the new powerful 0.8mm nozzle in place, it's time to print more things!

First thing: Feet for our shoe bench. Its current height is such that the Roomba can almost but not quite get in there, and might well just get stuck. So I designed some simple feet, rounded and flanging out towards the bottom. My goal was to make it slope non-linearly, but I started with the straight slope and did a test with that. Doing a draft print using minimal infill and thin walls, I was still able to not just sit on the corner it was supporting, I could plop myself down with force, and all it would do was creak.

Having confirmed the design, I added a simple function to curve it. The trick to that is to create a function that goes from 0 to 1 but with a slant. Good candidates for this are square and square root, this is what I ended up using:

/** A function that given i from 0 to max starts at 0 and ends at max,

    but slopes inwards in between. */

function inSlope(i, max) = i * (sqrt(max/i));

Note that I give it not a value between 0 and 1, but two values that combine to give that. That makes it easier to plot into an existing design. This gives a pleasant volcano-like shape:

With the 0.8mm nozzle, I can print two of them in 1h18m, using 68g of filament. With a 0.4mm nozzle and the default 0.2mm Speed setting, it would take 3h3m but only use 53g - the difference in filament use probably due to the infill being twice as thick without there being half as much of it.

While printing the second pair, the printer did something amazing that I never expected to see. Part of the edge of the first layer had curled up on itself (probably should tune the Z offset separately for each layer thickness), so when the hotend came back to that spot on the second layer, it hit this bump. At which point, it said "Crash detected", moved the hotend off to one side presumably to wipe it clean, then moved it back and simply continued printing! More simplistic printers would either have torn off the print, leading to a messy blob on the hotend, or at least have pushed the X axis out of whack. I had at most expected it to detect the crash and stop, not to fix it itself!

Here's the final result in action:

Next thing is a hook for our fly zapper, which has otherwise had diverse less-than-optimal homes and which also has a rather strange loop for hanging it, so normal S-hooks tended to fall off when removing it. We happened to have some shelf railing pre-installed in a tiny side room to our kitchen, so hacking up some hooks for that was simple. The prints did end up being larger than would fit, so I had to redo it a few times. I guess the 0.8mm nozzle is too imprecise for this kind of work, but with a few adjustments it worked:

I was also looking at doing some auto-watering boxes, but the size I wanted turned out to make it use more filament than I found reasonable.

For the dresser next to Mickey's comfy chair, I made some simple hooks fitting the top edge, allowing her to hang some bags there:

Weird-eye view of the hooks

And finally, in preparation for getting more filament (the white already ran out), I printed two master spools, so I don't have to contribute to plastic waste with the empty spools. It's enough that I contribute with failed prints. The astute observer will notice a veritable spider's net worth of stringing here. Those can be melted away relatively easily with a flame, but it would be better without them. I did some temperature towers (using Bob's sneaky gcode) and found that a combination of printing at 220°C and 3mm retraction gave much better results.

With default settings

With 3mm retraction, 220°C