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.

Category: Machine Shop

Mechanical widgetry

Tour Easy: PTT Button Replacement

After five years and one cleaning, the PTT button on Mary’s Tour Easy became increasingly intermittent, both failing to activate solidly and sticking closed (there being nothing quite like a hot mic during a good hill climb), so it’s time for an autopsy:

Failed PTT Switch – as extracted

The snap dome is much more scarred at the central contact:

Failed PTT Switch – snap plate

That might be a gold flash coating, but it’s pretty well worn away where it hits the central contact:

Failed PTT Switch – center contact

Those scratches surely happened during the previous cleaning pass, as I don’t see any way for the dome to create them.

The corner contact also shows some scuffs, along with a scar where the dome corner pivots:

Failed PTT Switch – edge contact

All in all, though, it worked quite well.

The replacement switch, also intended for indoor use on a keypad or some such device, pivots around the front edge and may be easier for her fingertip to activate:

New PTT Switch – installed

Hot melt glue seems vastly underrated for how wonderful a structural material it is.

If this one lasts five years, I’ll be perfectly happy.

2024-07-31
Laser Test Paper: Plant Label Testing

After a month outdoors, the (failed) flexible strip labels show signs of wear:

Laser test paper – 1 month weathering

The upper one has a coating of clear rattlecan paint and looks much the better for it. The lower one is bare, but also suffered greatly from being folded and tucked through itself, so it started in worse condition.

Perhaps the paper will work better when stuck to metal plant label stakes, although I suspect the adhesive sheet will fail first:

Laser test paper – small plant labels

Those are random names; Mary tells me the proper label format has the Latin nomenclature on the first line.

They’re now out on the patio for observation.

For whatever it’s worth, my fascination with this paper boils down to “it’s cheaper than Trolase” for applications not requiring archival quality and duration. If it lasts Long Enough, that’ll be Good Enough.

2024-07-26
Speaker Re-Foaming

Having recently promoted a pair of Radford Tri-Star 90 speakers to the Sewing Room, it was time to make them presentable:

Radford Tri-Star 90 speakers – taped grill

The original foam grill covering had disintegrated and left fossilized adhesive over the metal gridwork. Being not much for historic accuracy, I used double-sided duct tape (the blue barrier film peels off) and stuck some allegedly acoustic foam in place:

Radford Tri-Star 90 speakers – re-covered

The foam is a single sheet wrapped around three sides and, after some whittling, measured 19.5 inches tall and 19.25 inches wide. The width surely depends on how snugly it’s stretched, so allow a bit more and trim to fit.

Duct tape probably isn’t the right adhesive for the job, but we’ll see how long it lasts. I really did not want to use spray glue and doubted my ability to slobber liquid stickum without oopsing the cones.

The speakers sounded great back in the day and they definitely sound much better than my deflicted ears can hear now. Mary thinks they’re OK and that’s all that matters.

Patrick, wherever you are: thanks!

2024-07-25
COVID Buffer Extraction Tube vs. Acrylic Solvent Adhesive

This seemed like a good idea for dispensing small drops of acrylic solvent while gluing spiders together:

COVID test Buffer Extraction Tube – adhesive hack

It’s the Buffer Extraction Tube from a COVID-19 rapid test kit with a short brass tube jammed in its dropper tip. The longer brass tube let me suck that dose of solvent into the tube without any of the hassle required to pour the liquid from a big can into a little tube.

Tell me you didn’t save those things because you thought they didn’t look like they might come in handy for something.

Well, that turned out to be a Bad Idea™, because whatever plastic that tube is made out of cracks when exposed to the hellish mixture in SCIGRIP #3 solvent adhesive. The tube didn’t dissolve or melt, it just cracked when you (well, I) squeezed the sides.

My Box o’ Test Kits has a few other types of tubes, but I used a syringe from the inkjet refilling era and that worked OK.

2024-07-24
Slotted Spiders

Starting from an SVG file set up for 3 mm material, apply the usual optimizations & tweaks to get a usable LightBurn file, then go nuts:

Spider Collection

The big one is two cross-laid layers of corrugated cardboard using up the better part of three Home Depot Large moving boxes:

Spider – LightBurn layout – 2x cardboard

That little bitty grid is the 700×500 mm laser cutter platform, so I just slap a sheet of cardboard in place, update the workspace from the camera, select the next layout, drag it over the cardboard, and Fire The Laser.

The smaller cardboard spider over on the left is built with a single cardboard layer and succumbed to the square-cube law: the legs are entirely too bendy for the weight of the body. Although it’s not obvious from the pictures, both cardboard spiders have a keel plate I added under the body to support most of their weight.

The brightly colored little spiders got a coat of rattlecan paint without any underlying primer and definitely look like that happened:

Spider Collection – detail 2

The edge-lit fluorescent green spider is sized around 2.9 mm material, the clear spider uses 2.3 mm acrylic, and the chipboard one in the background is at 1.8 mm:

Spider Collection – detail 1

The eyes are fluorescent red or green acrylic with concentric circles engraved to catch the light. They’re more effective than I expected, although they won’t look like much after dark.

We now live in a neighborhood with youngsters and Halloween this year will be so much fun …

The WordPress AI image generator caught the general idea of “cardboard spiders”:

Spider – WordPress AI image

So. Many. Legs.

2024-07-23
Slotted Beetles

Continuing the theme of slot resizing & overall scaling:

Beetle Collection

The original model has 3.0 mm slots and arrived in CorelDraw format requiring a bank shot off InkScape to create an SVG file suitable for LightBurn. After the usual cleanup & optimization, I applied global rescaling to match the available material.

The smallest beetles use 1.9 mm chipboard:

Beetle – 1.9mm chipboard

Everything is held together by ordinary wood glue, squeezed together for a few moments until the two parts no longer slide around.

One layer of 3.9 mm corrugated cardboard:

Beetle – 1x cardboard

The fancy gold & hologram decorations come from what’s surely non-laser-safe PSA vinyl sheets, cut by offsetting the top layer shapes inward a reasonable amount. The eyes come from random colored paper or painted chipboard.

Two layers of cardboard add up to 8 mm:

Beetle – 2x cardboard

That’s purple paper left over from the layered paper quilt blocks and, obviously, my glue stick hand is weak.

Three layers of cardboard makes each part half an inch thick:

Beetle – 3x cardboard

That bad boy needs black stripes on yellow in the universal “Fear me! I am a seriously dangerous creature!” danger marking.

The layers are laid out with crossed corrugations to make the part less bendy, which is more necessary for the relatively slender legs.

It’s two feet long and chewed up the better part of two Home Depot Extra Large moving boxes:

Beetle – LightBurn layout – 3x cardboard

The gridded rectangle represents the 700×500 mm laser platform.

The little ones are kinda cute and not too threatening:

Beetle Collection – 1.9mm

Yes, that is one of the Goldbug Variations.

2024-07-22
Slotted Elephants

Continuing the theme of slot resizing for various materials:

Elephants – 3.8 and 1.5 mm

The DXF pattern imports directly into LightBurn and requires the usual joining / closing / optimization before all the slots resize in unison. Doing the resize changed the slots from the original 3.0 mm to the 3.9 mm required to convert a cardboard moving box into a pachyderm.

The leg sections turned out to be a bit too thin for corrugated cardboard, so the corrugations came loose from the surface sheets, although the tail looked much more realistic. Stipulated: corrugated cardboard is the wrong material, but I really didn’t need a big MDF elephant looming over everything else.

The smaller elephants, both in 1.5 mm thick materials, come from a global resize applied through the LightBurn Numeric Edit toolbar:

LightBurn Numeric Edit – percent resize

The ratio makes the slots become the new size, with the entire rest of the design scaled around them. This works if you don’t much care about the overall size, but is rare in actual practice where you need a model “that big” with the slots fitting “that material”.

But the pieces just slid together:

Elephants – 1.5 mm detail

I put dots of cyanoacrylate in the acrylic joints, although the vapors scarred the surface enough to remind me why that’s the wrong adhesive for the job when you care about surface quality. Dots of wood glue hold the chipboard elephant together, with a quick shot of clear rattlecan paint to knock down the smell of the charred edges; I’d say the color came out about right.

All in all, they worked out rather well.

2024-07-19