Last miniature test, I promise

Having had some luck with the 0.04mm layer (yes, that's 40 microns, less than what many resin printers advertise), but also having read that thinner layers may need higher temperatures, I tried to vary that. Also, due to stringing, I tried to vary retraction. Results were mixed, shown  belowwithout any cleanup.

This one (front and back) is (accidentally) at 230°, with 1.2mm retraction.

This is also at 230°, with 2mm retraction:

And finally, at 235° and 3mm retraction, an accidental skeleton king:

Clearly, 235° is too much, though it should also be mentioned that these were done after a failed attempt at a temperature tower that broke loose from the print bed. 230° is also a bit high, I liked the 225° better, the print was smoother. And 3mm retraction is quite obviously a bad idea here. 

This temperature tower was done at 0.16mm layer height, still 0.25mm nozzle, and it's really hard to tell any difference between the temperatures. Actual temperatures are, from the bottom, 225, 215, 205, and 195. There is a bit more bridging droop at 225, and the overhang seems a bit less regular at 205 and 195. The most interesting difference is that at 195, the surface is matte rather than shiny. 

Full-size front shot, layers clearly visible:

These shots were taken in my new mini-softbox, a cut-open plastic container. It can bounce the light enough to give reasonable shadow,s while the highlights of irregularities are easy to see in the sun. Lens is a 60mm macro at 1:1, f/16 on APS-C.

Now back to a regular 0.4mm nozzle and some normal prints.

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

A good, long service

One of the first complicated pieces I made, way back in early 2016, was a replacement foot pedal for one of our trash cans. Finally yesterday it met the end of its life, breaking off partway through:

Three and a half year of being stepped on multiple times a day is not bad, though. I shall give it a second chance using either epoxy or contact cement, but I'm proud of how well it held up.

In other news, the printer has had software issues after getting updated. The Display ETA plugin for OctoPrint was adding malformed text to the M117 commands, which made the printer reject it. Apparently plugins are not entirely harmless.

I also had a nasty crack in the extruder block:

This was causing the gears to move apart a bit and start skipping, the noise from which is how I eventually noticed. Notice how the crack follows the print, then follows the edge of the circle down to the nut trap (there's another nut trap on the left of the picture that the crack also went through). If I had printed for much longer, it would probably have fallen apart entirely. As it was, I was able to use good old-fashioned contact cement to extend its life:

I suppose one could actually pre-treat it with contact cement, to fuse the layers a bit better.

But it's not all doom and gloom. I haven't been keeping up with the posts, but that doesn't mean I haven't printed things. Here are a few of my successful outcomes:

I added some feet to a container in the bathroom, to avoid water collecting underneath (and to prevent sagging). I sprayed them with PlastiDip for extra stability and glued them on with contact cement. Disappointingly, when  I took this shot, I notic ed one of them was loose.

I printed a bunch of minifigs for our DSA campaign, several of which I painted. They must have been blessed, for the ambush we first employed them in went above all expectations - three shots took down three guards, the rest surrendered.

Team Green vs. The Red Rangers

Truth be told, my printer isn't nearly good enough for proper figurine printing. The heads are basically blobs with faint hints of facial features. I'm curious to try HeroForge, though it's expensive enough that I'll only do it for my own character, not a whole army.

I printed some new hangers for my plant pots, this time in white PETG, which should be more resistant to heat. Unfortunately, I forgot to mirror one, so now they hang kinda funny. And I only had a small sample of PETG, so I couldn't just reprint.

I'd previously made a base for our salt- and pepper-grinders, so they wouldn't dirty the table. But when moved, they had a tendency to fall off, so for safe-guarding during transport, I added the obvious thing - tentacles:

They were done by defining just one third-degree polynomium, which I then copied and rotated. It took some fairly arbitrary tweaking, but with only a single test print I got a usable holder. Does your kitchen have tentacles? If not, maybe it's time you ask yourself why not?

We have an extendable table from Ikea with a simple plastic locking system. Unfortunately, one of the lock parts fell out and disappeared, but printing a new one turned out to be quite easy:

And even earlier in the year, I made a sturdier version of the drilling guide for the magnetic poster sticks I had been wanting to make for years. This one worked. I'm still amazed that my printer can print a horizontal beam into thin air - the fan duct certainly helps make that possible, but still.

I'm slowly starting to consider replacing this old workhorse with a more modern machine that doesn't need as much care. Levelling is still a sore point - I have a probe mounted (as seen below) but not connected, I have nothing telling me when I run out of filament, nor if the motors actually move the amount I tell them to.

Finally, here's a small video of my machine at work, printing a test piece for a little holder in the kitchen. I like the sound of the movements, it's very futuristic. As is the ability to design and print useful pieces in your own home. We're truly living in the future.

More printing success than you can shake a piece of filament at

After cleaning the stripped filament from last time off the hobbed bolt, I printed the phone cover with my regular filament, just to see if it would fit. And it does! My calibration is great! My design, however, needs a bit of tweaking, but that was exactly the point of this print. The bottom holes should be a bit higher, the audio jack a bit further right, and both possibly enlarged. I'm quite amazed, though, that the overhang for the USB-C jack came out so nice - that's without any support:

The hole on the side needs a bit of enlargement, and the sides of it should be slanted for easier access:

On the back, there is a little bit of offset to the left, and the hole for the fingerprint is up too far. Plus, the sphere I used to make the fingerprint scanner easier to touch left a few strands. That might just be the effect of having a part that's thinner than the layer height. I can reasonably make it more steep.

Most importantly, at the very start of this print, I caught the extruder skipping a few steps, and just to attempt to save the print, tightened the idler screws somewhat, to where the springs are almost fully compressed. That helped! So now I know that the stripping has been partly due to the idler being too loose. That clears up one of my remaining questions.

After that, I printed the AAA battery dispenser again, this time at 90% scale. Unfortunately, part way up it the hotend came a bit loose (the mounting system is crap and I want to print a better one), and I had to fasten it again while printing. The result can store batteries, but isn't as nice, and tends to have the batteries go sideways:

Having noticed the very nice overhang on the phone cover, I thought it'd be nice to have a test piece for overhangs. So I maded one (shared on Thingiverse):

Overhang test with the overhang width in mm.

This shows that I can actually do up to 18mm of overhang, which is pretty incredible. It also shows "ringing", especially after the letters, which I should fix. While most troubleshooting guides seem to blame speed or acceleration settings, I think in this case the slightly loose hotend may be to blame.

The back side of the test piece has circles, where while the overhang is technically smaller, the ends fall down, making them a bit unclean:

I tried also doing this test without my fan running, to see what difference that made. Not quite as much as I expected, but still there's a lot more drooping:

Closeups, first without fan:

Then with fan:

The difference is striking. Having a fan is definitely helping. And this is just with a simple front-mounted fan, no fancy ducts. I have an idea for a fan duct setup with the fan mounted separately and blowing through a tube, but haven't gotten around to it yet. That would at least solve a bunch of annoying mounting issues. It might be more easily done with the radial type fan, possibly mounted on the left side of the extruder motor. The "ducts" could be a wide ring with four little blowers instead of a hotend-specific circle. The quality I'm getting from just blowing in the side tells me that getting every last drop of air placed just right is less important than actually being able to easily mount it. Plus, I want to be able to see the print in progress.

I also finally got around to fixing the loose wires I had had hanging around, getting rid of the last crocodile wire. It's better, and I won't have to worry about the fan wires falling down and catching on the corner clamp, but I still need a few cable ties to make it perfect: