Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
That’s eight months of weathering on MDF covered with indoor urethane sealant and it’s not as awful as I expected: the MDF didn’t actually disintegrate, it just collected some mold / mildew / crud.
A closer look:
Please Close The Gate – weathered MDF – detail
The black paint survived surprisingly well.
I hadn’t paid much any attention to the edges, so they got covered with random amounts of black paint and urethane. It seems that’s where the disintegration starts:
Please Close The Gate – weathered MDF – side view
MDF definitely isn’t the right material for an outdoor sign and I knew that going in, but it’s cheap and readily available, which makes up for a lot.
For comparison, they looked nice right after installation:
A warm day let me shoot the engraved signs for the Vassar Community Garden gates with rattlecan black:
Please Close The Gate – masking tape peeled
The full sheet of orange acrylic arrived with plastic protective film on both sides, which I planned to use for paint masking. Alas, one side also had a wrinkle running its length that ended up on two signs, so I replaced that film with blue masking tape.
As fate would have it, the first side of the first sign I peeled had masking tape and produced what you see above.
Things went bad in a hurry. The paint had no adhesion whatsoever to the plastic film and fell off in flakes as I peeled the film away:
Please Close The Gate – plastic peeled
I assumed the flakes would just fall off the signs, perhaps with a little persuasion, so I peeled and weeded all the signs before cleaning them up.
Although the paint was fully dry, when the molecularly smooth surface of each paint flake touched the molecularly smooth surface of the newly exposed acrylic, the two instantly and permanently fused together.
There were a lot of flakes:
Please Close The Gate – plastic peeled – detail
Removal techniques that did not work:
Vacuuming with a brush
Gentle rubbing with a soft cloth
Firm rubbing after spraying with acrylic cleaner
Scraping with a plastic razor blade
So I deployed a P220 grit sanding block and wrecked the glossy surface of both sides of all six signs. I briefly considered trying to recover the finish by sanding them all up through about 2000 grit, then came to my senses: my sanding arm is weak.
Careful examination of the last picture shows several places around edges of the circle where the plastic film melted into a blob that blocked the paint, rather than vaporizing. I used enough power to engrave only about 0.3 mm deep (because they’re engraved on both sides), but the transition wasn’t fast enough for a clean edge.
They don’t look as nice as I’d like, but they’re good enough for the purpose:
Please Close The Gate – installed
The acrylic sheet is more see-through than I expected, at least when backlit by bright sunlight.
Please Close The Gate – seethrough
Next: we discover what happens to UV-stabilized orange acrylic and black outdoor paint over the course of a year in garden sunshine.
A recent Squidwrench meeting provided the opportunity to make a couple of racks for an assortment of Refresh Tears / Liquigel bottles:
Refresh eye lube – storage cases
I used chipboard to find out if the cross plates would stiffen the floppy 1.1 mm sheets enough for this light duty. Indeed, the overall structure becomes a nice rigid box, even though the feet and corners can’t withstand much abuse.
The finger joints use the default settings, which produce a lot of fingers along the edges. This turns out to be a Good Thing, as it gave the yellow wood glue plenty of opportunities to bond the sheets together.
Combining the default 5° slope with nine bottles along each level wastes a tremendous amount of vertical space. The adjacent racks hold three much larger cans per level, so roughly the same space doesn’t look like much. In retrospect, a 3° slope should work for smaller bottles.
And, yes, the squash on the lower shelf store nicely and become yummy meals all winter long.
Long ago, I gave Mary a box of 100 empty bobbins for her Kenmore 158 sewing machine, with the intent she would never again have to unwind a bobbin to put new thread on it. This worked so well I did the same thing for her Juki, with the result she needed somewhere to store all those filled bobbins.
Her work table has a shallow drawer, so we tried this out:
Watching all those little rectangles fall out just never gets old:
Bobbin Storage Case – cutting detail
I ran off a test tray in ordinary chipboard that works just as well, but lacks the pleasant appearance and feel of the TroCraft. Clear 1.5 mm acrylic would probably work, at the cost of requring a much neater glue job where the dividers meet the walls.
The spacing is a bit tight to pluck a bobbin from its slot between two others, but now she has enough space to arrange them as needed, with empty spaces around the most-used colors. I offered to carpet the drawer with bobbin trays, but she suggested waiting until these fill up.
As practice in using the laser to engrave a figure to a known depth, this seemed appropriate:
Envelope Opener – original
The black envelope opener on the right came in a long-ago surplus deal and worked really well, which I cannot say for the retail replacements I got a few years back.
The tan envelope opener on the left is an obvious case of IP theft, copying the size and shape using a scanned image:
Classic opener – knife blades – scan
The two blades seemed like good candidates, with the lower one winning the contest:
Kobalt 78010 Mini Utility Knife Blade mask
Although the pack of “mini utility knife blades” sports a Lowe’s Kobalt part number, they no longer carry that item. You can find plenty of identical blades elsewhere, so they’re not a rare collectible and I have plenty of backup.
Put the outline of the opener on a cut layer, put the blade on an engraving layer, orient appropriately, and make a mirror-image duplicate:
Envelope Opener – LB Layout
The original opener is a touch over 3 mm thick, so the settings engrave 0.25 mm into the surface to make a blade pocket, then cut the shapes from 1.5 mm TroCraft Eco:
Envelope Opener – cutting
After all the cutting was done, it looks about as you’d expect:
Envelope Opener – interior layout
Slather with yellow PVA wood glue and apply too many clamps:
Envelope Opener – clamping
Next time around, I’ll round off the edges before assembly, but that’s in the nature of fine tuning:
Envelope Opener – detail
The TroCraft sheet engraves so cleanly that, were I to go into mass production, I’d set up a fixture for grayscale engraving shaping the perimeters.
Obviously, this makes no economic sense, but it does produce a considerable amount of satisfaction, which is pretty much all that matters for such things.
Without looking at the captions, match each of the following pictures with its description:
a failed ZYE MYJG60W-Y-1 (came with OMTech laser)
an unbranded MYJG60W replacement from OMTech
a Cloudray M60 (bought as a backup)
HV Power Supply – ZYE MYJG60W-Y-1 – failedHV Power Supply – unbranded MYJG60WHV Power Supply – Cloudray M60
That was easy, wasn’t it?
As I said in the forum:
My guess is there’s only one ZYE factory (or a dozen clones) producing all the power supplies, then applying whatever sticker the order calls for on the case before dropping it in the carton.
Perhaps Cloudray buys more quality control than the anonymous “brands”, but I wouldn’t lay much money on finding more than two QC bins at the end of the assembly line: either it runs or it doesn’t.
Mary cut out a simple cloth liner for her ResMed F20 CPAP mask (a.k.a. “cushion”) and snipped away at the fabric until it felt about right. I scanned the result and turned it into a bitmap mask (which is entirely different from a CPAP mask):
Mask liner – scanned
Given that as a start:
Import the scanned image into LightBurn
Fair a few curves around the perimeters by hand, rather than attempting to trace the thing
Rationalize the sizes
Make it symmetric
Cut a few prototypes while tweaking the fit
Which leads to a pattern like this:
CPAP Mask Liner – F20 knit – spline fit
The rectangular upper part forms a simple eyeshade that also keeps minor leaks from disturbing her sleep. Your mileage may vary, depending on how much you toss and turn during the night.
We found the fit depends on the fabric, with woven fabric requiring a taller opening:
CPAP Mask Liner – F20 knit woven – LB layout
The engraved legend verifies I used the proper design for the fabric:
Laser cut CPAP Mask Liner – F20 – knit fabric
The opening has tabs holding it in place while cutting, at least until we get this down to a routine.
Then make enough for a while:
Laser cut CPAP Mask Liner – F20 – production
The usual woodstove odor vanishes after half a day sitting atop the clothes washer. Putting them in a mesh bag and tossing them into the regular wash refreshes them after use.
The Smell of Molten Projects in the Morning 
