Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
The flat robot vacuum assigned to clean the floors around here would occasionally get stuck under the leg of my Husky workbench-as-desk and fail to complete its mission. Living in the future makes solving that problem a matter of minutes:
Husky workbench caster feet – installed
The upper rim captures the locked-in-place wheel in a 35×25 mm recess atop the middle 45×35 mm slab, with a 2.5 mm cork layer on the bottom. Laser-cut, of course, glued with ordinary yellow wood glue, and clamped for about half of a Squidwrench remote meeting.
Raising the desk by 5.5 mm gives the Flat One juuust enough clearance to scuttle under there:
The small bearings are 25 mm OD, with correspondingly small clearances between their moving parts, but they all spun easily after a bit of breaking in.
As with their larger cousins, the orange PETG bearing has the most axial play and worked just fine right off the platform. The gray PETG-CF bearing was jammed and required concerted effort to get the gears rolling, but now has essentially no axial play while turning easily. The snappy-looking orange and black bearing has very little play and feels the best of the three.
The single-material bearings take about 20 minutes to print, while the mixed material one requires 80 minutes due to the extruder purging and nozzle clearing. The larger mixed material bearing took more than three hours, but time doesn’t scale as the cube of the size because changing materials runs at a constant time:
Small Planetary Gear Bearings – PETG PETG-CF with wipe towers
The smaller mixed gear produced the smaller wipe tower on the right, but changing materials remains an expensive process. Of course, if you were doing this in production, you’d make a couple dozen of the little things in one job: the machine would spend most of its time squirting out planetary gear bearings with the same number of material changes building the same size wipe tower.
They’re slightly too small for my fingers and surely pose a choking hazard to children, but they’re definitely cute.
A small tweak to the venerable spoon drainer adds a configurable cutout adapting it to a slightly different dish drainer rack:
Measuring Spoon Drainer – solid model
Which lets it snuggle into the corner:
Measuring spoon drainer – installed
Both the old and new racks had coated steel loops stuck into rubberoid feet perfectly suited to collect water and eventually rust the loops. Given a new rack, I figured potting the feet in JB PlasticBonder urethane adhesive would help forestall the rust:
Rubbermaid dish drainer – foot potting
I wish it were white, rather than black, but the only other color choice is tan and I can’t wish nearly that hard.
So I loaded up the same STL in Prusaslicer and made three more:
Planetary Gear Bearing – M2 vs MK4
Both pictures show the same red bearing, done in PLA on the Makergear M2. The other bearings are PETG and PETG-CF on the Prusa MK4 + MMU3.
The blue bearing has about 5 mm of axial play, a bit more than the red.
The gray bearing is PETG-CF and has maybe 1 mm of axial play, which agrees with my original observation that an Extrusion Multiplier of 1.0 results in slightly overstuffed carbon fiber parts. It’s not much and, frankly, produces a better fit in this case, but it’s different than pure PETG. Which should come as no surprise, of course, given that it’s 15% carbon.
The gray-and-orange bearing looks spectacular in person and has about 3 mm of axial play, roughly the same as the red bearing, which you’d expect from overstuffed PETG-CF and pure PETG.
The single-color bearings print in about 1.5 hours and the two-color one weighed in over four hours. Multi-material objects are do-able, but you gotta want the results.
I told Prusaslicer to wipe the orange filament into the gray infill during color changes (per the Wipe Tower doc), but those two gray parts have so little infill as to make no difference:
Planetary Gear Bearing – PETG PETG-CF with wipe tower
The wipe tower in that posed photo has a nubbly texture because the filament just gets squirted without regard to anything other than maintaining the basic tower shape.
Seeing things appear on the platform never gets old!
The model is the Steampunk Octopus (in retrospect, the lower-vertex NixFix version should print better with its under-engine braces). The tests were to see how well its articulated tentacles printed and whether I understood how PrusaSlicer’s Multimaterial Painting worked. The answers: “Perfectly” and “Undo is my copilot”.
They’re both in PETG, with the orange eyes & features painted onto the STL model using the Smart Fill tool type to select surface facets joined within a given angle. Getting that right requires some fiddling, because you (well, I) can inadvertently select & flood a nearby area.
With Halloween fast approaching, they should be useful:
In the process of fixing something else, I discovered my favorite desktop razor knife had a loose blade. There being nothing like a new problem to take one’s mind off all one’s previous problems, I obviously had to fix it before proceeding:
Razor Knife – broken collet thread
Come to find out the plastic screw tightening the blade collet had snapped. The remaining stub stuck out from the red ribbed nut just far enough to prevent sliding the nut out of the black plastic body, but jamming a small screwdriver through the body got enough traction to unscrew the stub. It’s threaded 8-32, despite being old enough to be Made in Taiwan.
The red plastic feels like HDPE or a similar un-glue-able material, so it was going to need a mechanical splice. A tiny 2-56 setscrew falls in the class of things my buddy Eks describes as “If your design needs those, you’re doing it wrong”, but sometimes you gotta do what you gotta do.
The little wrench in the background measures 28 mils for 0-80 setscrews, of which I have none and don’t expect to get any.
Anyhow, facing, drilling, and tapping the stub proceeded handily:
Razor Knife – setscrew in thread stub
You’d think I hadn’t faced off the end, but you’d be wrong. As far as I can tell, the end of the screw would be happy to break for as long as I’d be willing to try cutting it. Perhaps this indicates why it broke and suggests this repair will be temporary, at best.
Doing the same to the collet required a clamp to fit its slightly oblong body:
That’s aggressive stick-out for a little plastic rod, but sissy cuts saved the day; it faced / drilled / tapped easily enough:
Razor Knife – collet repair parts
Despite the non-glue-able plastic, I tucked some JB PlasticBonder into the recesses, screwed everything together, and coerced the 8-32 threads into alignment inside the plastic nut:
Razor Knife – collet thread alignment
Reassemble in reverse order after the adhesive set up:
The fixture in the lower left is just an MDF square with a 15 mm post of more MDF glued in the middle to align the pieces. The white disk is the adhesive sheet, cut to 119 mm OD to leave half a millimeter clear around the outer edge, thus avoiding embarrassing stickiness.
Peel one side of the adhesive sheet and drop it over the post sticky side up:
Double-faced DVD coaster – adhesive sheet ready
Drop one of the DVDs over it, label side down:
Double-faced DVD coaster – first disc on adhesive
Lift it off, peel the other side of the adhesive sheet, put it over the post sticky side up, and drop the other DVD on top:
Double-faced DVD coaster – finished
The data side of the discs has a 0.3 mm raised rim just inside the track zone, so they don’t sit exactly flat on the table and expect a slightly concave lower surface on the mug / glass / cup. Neither of those seem like dealbreakers thus far, although I’m sure somebody will object.
A ring or two of general-purpose glue, along the lines of E6000 urethane, would be significantly less fussy than cutting adhesive sheets.
The Smell of Molten Projects in the Morning 