The Smell of Molten Projects in the Morning
Ed Nisley's Blog: shop notes, electronics, firmware, machinery, 3D printing, and curiosities
Making the world a better place, one piece at a time
A filled box of worn-out clothing produced more shop wipes:
The last few pieces were a bit finicky, but provided good on-the-fly practice with linear arrays:
This trick never grows old:
I washed those neat stacks (in their very own load!), which didn’t turn out well:
They’ll get used no matter what they look like!
An addition to my morning cocoa makes it mmmm turn out better:
Start with an ounce of milk, dump in the rest of the ingredients, spin up the stirrer, and slowly add the 8 oz of milk that just reached the end of its 70 seconds in the microwave:
The green LED to the left of the speed knob runs from the PWM signal driving the motor, so it flickers visibly and interacts with the camera shutter.
Let it whir for a few minutes until all the cocoa bombs vanish and it’s ready for another 33 seconds in the microwave.
The most recent batch of cocoa arrived in an exceedingly vacuum-packed mylar bag, to the extent the bag resembled a brick and the solid cocoa within fractured into big chunks. Bashing the chunks with a fork got tedious enough to remind me of the stirrer I got to mix titanium dioxide for the yet-to-be-tried glass engraving.
Back in the day, the teflon shell molded on the magnet had a rib around its middle to make it pivot neatly on a point contact. This one is flat and dislikes spinning on the slightly concave cup bottom.
Protip: fish the stirrer out before sipping the cocoa, lest it become a tiny cow magnet.
Loading the bike batteries into the Rolltop Cupcake Box reminded me I hadn’t updated the Lip Balm Holder around the latest tube of sunscreen. My excuse was I didn’t quite know how to model the not-quite-elliptical shape of the Coppertone sunscreeen tube in OpenSCAD, but now I can bypass that whole problem:
The trick is to scan the bottom of the cap to get a high-contrast image:
Import the image into LightBurn, draw a circle tangent to the outside of the cap’s smaller diameter, turn the circle into a path, drag the nodes and twiddle the control points to create a symmetric shape just outside the cap, then outset the result by 1.5 mm for clearance around the tube:
That 3 mm of wiggle room lets us drop the tube into its socket without careful alignment.
The lip balm tubes all fit into 18 mm circles requiring no special design skillz:
The mid-left oval goes around the Coppertone tube.
The top-mid drawing shows the 3 mm outset around each of the pieces, with the smaller tubes arranged to put their midlines tangent to each other and the oval tube. LightBurn does not, as far as I can tell, have a direct way to align a shape tangent to two other shapes at the same time, but iterating at increasingly absurd zoom levels gets the job done fairly quickly.
Welding those shapes together produces the top-right drawing, which serves as the template for the lower set of layers.
Deleting the inner details produces the mid-right blob for the bottom layer.
Most of the layers come from 3 mm plywood, with edge-lit acrylic on the top and bottom surfaces:
Mary pronounced it better looking than the 3D printed version, which I agree clears a rather low bar, but it suffices for the job.
The LightBurn layout as a GitHub Gist:
A Genuine Kidde Fyre Freez CO₂ extinguisher that Came With The House™ finally found its ideal location:
It was last refilled 65 years ago:
I know it’s still good, because the label has its 4 lb 7 oz refilled gross weight stamped into it, which is exactly what it weighs today.
Walter Smith Welding Supplies may still be in business, perhaps in Poughkeepsie, but their former 18 Downs St location in Kingston has become Noble Gas Solutions:
Back then, you could call Smith Welding at a four digit phone number in Kingston: 5061. Nowadays, you must call Noble Gas with three more digits: 338-5061. As Charles Stross observed, something like 70% of the future is already in place, because infrastructure is so tenacious.
Heck, just look at that Quonset hut!
Keep calm and extinguish on:
Two thoughts spring to mind:
Seems to me a Fyre Freez will get cold enough to freeze skin while discharging, but I admit to not having actually tried it.
Anyhow, given the overall basement decor, the brackets have the right general style:
Here’s hoping its future will be as dull as its past …
After going through the LightBurn camera alignment / calibration process, I thought it would be interesting to see how well the corrected image matches the design grid.
Burn some holes and draw lines 10 mm in from the physical corners, like this:
Burn holes and lay in a 10 mm grid at the center point:
The center grid as seen through the camera:
That’s after adjusting the X and Y offset to align the center of the imaged grid with the center of the design grid. That’s using the non-faded image to make the target lines more visible.
The corner markers don’t quite line up with the grid, but they’re not off by much (using the faded image to make the grid more visible):
You could, of course, split the difference among all five sites, but I think having the middle of the platform be more accurate than the far corners makes more sense.
In any event, a few millimeters works for most purposes, even if you’d want to verify the alignment for critical operations before firing the laser in earnest.
Going through the LightBurn lens calibration and camera alignment routine produces an orthographic view of the laser platform from a camera with an ordinary lens perched somewhere above it.
Early on, I stuck a camera to the lid of my OMTech 60 W laser:
The uncorrected view from the camera (through VLC):
After calibration and alignment, LightBurn underlays this view of the platform behind the workspace:
The correction depends critically on the camera maintaining its position / orientation / focus, which turns out to be a bad assumption for the camera I’ve been using, because the (metal) focus locking screw binds directly on the (metal) lens threads. This works, until vibrations slightly loosen the screw and the lens shifts ever so slightly.
After noticing the focus had shifted again, I tucked a snippet of silicone insulation from some 30 AWG hookup wire into the screw hole to compress against the lens thread, then re-did the entire sequence with some attention to detail.
Pulsing the laser in each corner produced pinholes exactly 700×500 mm apart. One diagonal is 859.0 mm and the other is 861.5 mm, pretty close to the ideal 860.2 mm.
Next, to measure the offsets from some known positions …
Mary left the sticky card traps in the onion patch until the last onions came out, clustered them around the leeks, and collected them long after the season was over.
I count maybe twenty flies that might be onion maggot flies or cabbage maggot flies.
The cards protected the onion crop, failed miserably for the leeks, and did nothing for the nearby cabbages. Deploying the cards while planting worked very well, refreshing them after a month continued the protection, but the main fly season seems to end shortly thereafter.
All the sticky cards as a slideshow, starting with the three along the border fence:
The cards remain sticky to my fingers, but an adroit fly could skate over the debris field and emerge unscathed.
The Smell of Molten Projects in the Morning 
