More Laser-Cut Shop Wipes

A filled box of worn-out clothing produced more shop wipes:

Laser-cut Shop Wipes - assortment
Laser-cut Shop Wipes – assortment

The last few pieces were a bit finicky, but provided good on-the-fly practice with linear arrays:

Shop Wipe - LightBurn setup
Shop Wipe – LightBurn setup

This trick never grows old:

Laser-cut Shop Wipes - as-cut
Laser-cut Shop Wipes – as-cut

I washed those neat stacks (in their very own load!), which didn’t turn out well:

Laser-cut Shop Wipes - washed
Laser-cut Shop Wipes – washed

They’ll get used no matter what they look like!

Ed’s Fireball Cocoa: Magnetic Stirring

An addition to my morning cocoa makes it mmmm turn out better:

Cocoa magnetic stirring - magnet
Cocoa magnetic stirring – magnet

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:

Cocoa magnetic stirring - vortex
Cocoa magnetic stirring – vortex

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.

Lip Balm Holder, Laser Cut Edition

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:

Lip Balm Holder - installed
Lip Balm Holder – installed

The trick is to scan the bottom of the cap to get a high-contrast image:

Coppertone Sport Tube - lid scan
Coppertone Sport Tube – lid scan

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:

Coppertone Sport Tube - LB splines
Coppertone Sport Tube – LB splines

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:

Lip Balm Holder - LB layout
Lip Balm Holder – LB layout

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:

Lip Balm Holder - side view
Lip Balm Holder – side view

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:

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Laser Cutter: Fire Extinguisher Brackets

A Genuine Kidde Fyre Freez CO₂ extinguisher that Came With The House™ finally found its ideal location:

Fyre Freez extinguisher - mounted
Fyre Freez extinguisher – mounted

It was last refilled 65 years ago:

Fire Extinguisher Recharge Tag - 1957
Fire Extinguisher Recharge Tag – 1957

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:

Noble Gas Solutions - 18 Downs St Kingston - 2019
Noble Gas Solutions – 18 Downs St Kingston – 2019

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:

Fyre Freez extinguisher - step 4
Fyre Freez extinguisher – step 4

Two thoughts spring to mind:

  • Most kitchen fires start waist-high (it’s the late 1950s: where else would she be?)
  • She’s gonna lose skin on that metal tank

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:

Fyre Freez extinguisher - bracket detail
Fyre Freez extinguisher – bracket detail

Here’s hoping its future will be as dull as its past …

Laser Cutter: LightBurn Camera Accuracy

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:

LB Camera Cal - corner target
LB Camera Cal – corner target

Burn holes and lay in a 10 mm grid at the center point:

LB Camera Cal - center grid
LB Camera Cal – center grid

The center grid as seen through the camera:

LB Camera Cal - center grid overlay
LB Camera Cal – center grid overlay

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):

  • LB platform overlay - adj - rear left
  • LB platform overlay - adj - rear right
  • LB platform overlay - adj - front left
  • LB platform overlay - adj - front right

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.

Laser Cutter: LightBurn Camera Calibration

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:

OMTech Laser - camera mount
OMTech Laser – camera mount

The uncorrected view from the camera (through VLC):

LB Uncorrected Camera View
LB Uncorrected Camera View

After calibration and alignment, LightBurn underlays this view of the platform behind the workspace:

LB Corrected Camera View
LB Corrected Camera View

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 …

Onion Maggot Flies vs. Sticky Traps: Season Finale

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:

  • VCCG Onion Card - fence A - 2022-11
  • VCCG Onion Card - fence B - 2022-11
  • VCCG Onion Card - fence C - 2022-11
  • VCCG Onion Card - plot A - 2022-11
  • VCCG Onion Card - plot B - 2022-11
  • VCCG Onion Card - plot C - 2022-11
  • VCCG Onion Card - plot D - 2022-11

The cards remain sticky to my fingers, but an adroit fly could skate over the debris field and emerge unscathed.