The Smell of Molten Projects in the Morning
Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Mechanical widgetry
Mary brought this back from the garden after it fell over while she was working in that plot:
Another one returned a few days later in somewhat better shape:
We already knew lower-case letters were a bad idea and now we know a thin slab of untreated wood might survive two months when jammed into the ground.
Nothing unexpected, of course.
At least the lasering technique should come in handy for something else used in more salubrious conditions.
Confronted with a nice metal eyeglass case that had lost its original liner, I traced the outline on paper and scanned it:
Unlike the plastic Zenni cases, this one has nice straight edges, so:
Then:
1 so it cuts lastWhich looks like this:
Then Fire The Laser into a sheet of EVA foam:
Stuff it into the case, do another one in brown, and the result looks kinda like it should:
That was easy …
Some years ago we acquired a free quartet of aluminum-frame patio chairs in need of new straps and feet. Eventually enough straps broke to force me to re-strap the things and I finally got around to replacing the badly worn OEM feet:
The small drilled holes let me yoink most them out with sheet-metal screw attached to a slide hammer, then apply the Designated Prydriver to the most recalcitrant / broken ones.
Some feet had worn enough to expose the aluminum tubes, but most had at least a thin layer of plastic:
Obviously, I should have stripped and repainted the frames (if that’s possible, as they’re probably powder-coated), but a man’s gotta know his limitations and this job needed to get done.
One might think patio furniture replacement feet are cheap & readily available, but no amount of keyword engineering produced search results with any degree of assured fit, so I conjured adapters for screw-in feet from the vasty digital deep:
This was a long-awaited opportunity to explore the BOSL2 library and it worked wonderfully well. Each adapter is whittled from a huge hex nut with threads that perfectly fit the M8×1.25 stud, which stands vertically through the middle of the (slightly oval) bottom surface parallel to the floor.
The front tubes have a 5° angle with respect to the vertical:
And the rear tubes are 15° off:
Each adapter has an orientation notch pointing toward the front of the front leg and the rear of the rear leg:
I expected to apply adhesive on the inside and outside of the adapters, but they tapped firmly into place inside the legs and the studs screwed firmly into them, so we’ll see how they survive in actual use. I expect the studs to rust after a while, but that might not be the most awful thing ever to happen.
The OpenSCAD source code as a GitHub Gist:
| // Patio chair foot adapter | |
| // Ed Nisley – KE4ZNU – 2023-06 | |
| include <BOSL2/std.scad> | |
| include <BOSL2/threading.scad> | |
| LegAngles = [5,15]; | |
| /* [Hidden] */ | |
| ThreadThick = 0.25; | |
| ThreadWidth = 0.40; | |
| HoleWindage = 0.2; | |
| Protrusion = 0.1; // make holes end cleanly | |
| function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit); | |
| ID = 0; | |
| OD = 1; | |
| LENGTH = 2; | |
| inch = 25.4; | |
| //———————- | |
| // Dimensions | |
| LegTube = [18.8 – HoleWindage,22.5,0]; | |
| Stud = [8.0,1.25,10.0]; // M8x1.25 foot stud | |
| FlangeBase = 3.0; | |
| //———————– | |
| for (i=[0:len(LegAngles)-1]) { | |
| ang = LegAngles[i]; | |
| FlangeIncr = LegTube[OD]*tan(ang); | |
| Flange = [Stud[0],LegTube[OD],FlangeBase + FlangeIncr]; | |
| translate([i*1.5*Flange[OD],0,0]) | |
| difference() { | |
| translate([0,0,0*-FlangeIncr/2]) | |
| threaded_nut(2*Flange[OD],Stud[0],1.5*Stud[2],Stud[1], | |
| anchor=BOTTOM,bevel=false,$slop=0.2); | |
| rotate([0,ang,0]) { | |
| translate([0,0,FlangeBase + FlangeIncr/2]) | |
| tube(4*Stud[2],2*Flange[OD],LegTube[ID]/2, | |
| anchor=BOTTOM); | |
| tube(4*Stud[2],2*Flange[OD],Flange[OD]/2, | |
| anchor=CENTER); | |
| } | |
| cube([Flange[OD],ThreadWidth,2*ThreadThick],anchor=BOTTOM+RIGHT); | |
| } | |
| } |
They’re not fancy marquetry, but they look pretty good:
The darker areas are laser-engraved with the usual SCP warning label geometry.
The left set was engraved through blue masking tape, which increased the exposure, added no benefit, and required fiddly cleanup. Won’t make that mistake again.
The middle one has the darkest wood of the set with the lighter part not exposed to the laser.
They’re slightly smaller and much lighter than the plastic versions in order to fit them on the remaining DIY veneer plywood from the knitting stitch counters.
Rather than make another fixture for the backside branding, I cut adapters using the two outlines and dropped the hollow triangles into the fixture:
Two layers of veneer feel about right, although the layers should not have their grains oriented in parallel as these do. The PSA sheet on the back veneer holds them together, but they’re too flexy for confidence.
The contrast between gentle natural wood (using a generous interpretation of “natural” for veneer with a PSA layer) and the SFnal SCP warning label symbology is definitely amusing.
Laser cutting the Danger Zone coasters with the proper kerf offset for a good fit produced a pile of waste pieces from the other side of the kerf that seemed too nice to throw out. A bit of rummaging in the Basement Shop Warehouse Wing produced a battered magnetic sign that fell off the side of another truck and some casual searching suggested the material was laser-cuttable, whereupon this happened:
The trick is to cover the label side of the sign with adhesive sheet and the refrigerator side with blue painter’s tape, thereby simplifying the inevitable cleanup. Cutting through the adhesive produced poor results, perhaps due to molten adhesive or the sign material (which is almost certainly non-laser-safe PVC, alas) flowing into the cut and contaminating the process. Cutting through the blue tape worked reasonably well, albeit with a disconcerting shower of sparks.
The cutting pattern is the shape outline inset by about 0.5 mm.
Peel off the blue tape, remove the adhesive cover layer, align the outermost shape, press it down, add the rest, then admire the results:
The obvious difference in the “filament” size comes from two different kerf offsets, both on the order of 0.15 mm. It makes a big difference in narrow objects!
The Autonomous Object coaster created its own pile of scrap and you can see the gaps created by the mismatched kerf offsets:
Not works of art, but they came out nicely given where they started.
I recently replaced the hack-o-matic icemaker + fountain pump cooler with a LightObject Q600 water chiller, an entirely uneventful process. The Q600 has a back panel “aviation connector” with an alarm output for water flow (more precisely, lack thereof) or over / under temperature: pins 1 and 3 are closed during normal conditions and open during alarms (and when the power is off).
I finally wired the chiller into the OMTech 60 W laser’s internal water flow switch circuit, so that should either flow sensor have a problem with the water or the chiller detects an out of bounds temperature, the laser won’t fire.
You may recall the laser’s HV power supply arrived with its Water Protect input jumpered to ground, which I then wired to the lid interlock switch to (presumably) reduce the likelihood the replacement power supply will fail hot. The laser’s water flow switch goes to the Ruida controller’s WP input, where it behaves as it should.
Pin 2 of the chiller’s alarm connector is not connected to anything, so I added a safety ground wire for no good reason:
The dent in the evaporator tube (upper left) is worrisome.
While I had the side panel off, I jammed a strip of closed-cell foam around the base of the compressor to silence a truly spectacular rattle:
I think the three mounting screws (yes, of these two: one up, one down, for no reason I can see) are looser than they should be, but I’m reluctant to tip the whole thing over with a tank full of water to get at the nuts / bolt heads on the bottom.
The connectors have a twist-lock notch that you must release after removing the screw (on the far side) holding the shell to the body:
I repurposed a USB cable from the Big Box o’ Cables, wrapped with enough silicone tape to fill the cable clamp:
In retrospect, I should have paired the red + green and black + white wires, but nobody will ever notice. The drain wire carries the safety ground from pin 2 to the shielding, not that it matters. Both ends of the cable have identical connectors.
The laser cabinet has a convenient hole, albeit just a bit larger than required, which now has a simple adapter plate with the proper flats:
The blue ring is the same size as the hole, so as to ease lining it up, and the red perimeter surrounds the connector with strips of good double-sided foam tape for maximum sticktivity. Done in clear acrylic from the scrap pile, the platform’s internal lights give it that subtle blue-white hi-tech glow:
The doubled-up cable ties on the water hose barb connectors are a Good Idea™ due to the somewhat higher pressure of the chiller’s water pump. The bottom of that recess had traces of water on it and, of course, having a hose pop off its barb is a Bad Thing™.
The new connector is wired in series with the internal flow switch, using a trio of grossly overqualified silicone-filled splices:
I did not connect the safety ground from the chiller to the laser’s frame, because they do not share a common breaker circuit and I have better things to do than chase ground loops.
For whatever it’s worth, the gray cable that came with the laser might also be a repurposed USB cable, too: it has two fat wires and two thin wires, although it’s not wearing USB livery.
The laser is happy when the chiller is running and unhappy when it’s off, so life is good.
Chipmunks zip into drain pipes when they detect even a slight threat:
When I installed the drain pipes for the gutters & retaining wall along the driveway, I added a grate plug to keep critters from setting up housekeeping in what must look like an extensive cave network, although later experience showed I must clean debris out of the plug more frequently than I expected:
I didn’t glue the PVC pipes together, because I knew they’d need adjusting, so it was no surprise when the last section of pipe shifted enough to open a small gap, probably because my lawnmowing passes always proceed from right to left over the pipe:
The front yard chipmunk immediately claimed the pipe and zipped into the opening whenever we met on my way to the mailbox.
When I reconnected the pipe, the chipmunk knew something had gone wrong and started some exploratory excavation in about the right spot to find the missing tunnel entrance:
Not being one to rebuff the humble, I decided to make the world better:
It’s a short section of PVC pipe with a wood plug in the far end to keep what I grandly call “our lawn” from filling it up. I bandsawed a disk from a scrap of inch-thick lumber that used to be a door and introduced it to Ms Belt Sander often enough to make it a snug push fit in the pipe.
Some decoration seemed in order:
Which gives the place a nice, homey look:
Now, we’ll see whether the critters enjoy it as much as I did.
The Smell of Molten Projects in the Morning 