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

Skil Cordless Driver Re-batterying
In anticipation of upcoming disassembly & reassembly tasks, I finally replaced the long-dead NiCd battery in an old Skil cordless driver with an 18650 lithium cell from the Basement Warehouse Wing:

Skil Cordless Driver – 18650 cell overview

A USB charge controller sits in a slot carved into the plastic formerly supporting the NiCd battery’s charging jack:

Skil Cordless Driver – USB charger detail

Hot-melt glue holds everything in place.

The motor draws about 2 A under full load, which is a bit more than the charge controller wants to supply. I simply wired the motor (through its reversing switch) directly to the 18650 cell terminals, which is certainly not good practice, but seems reasonable given the intended use case.

A red LED shows the charger stuffing energy into the cell:

Skil Cordless Driver – charge indicator

You can see the blob of glue holding one of the acrylic cylinders left over from the gelatin capsule filler; only 99 more to go! I had to turn it down by about a millimeter, an operation best left to your imagination.

After an hour, a green glow shows the cell is fully charged:

Skil Cordless Driver – full charge

The original label proudly touted the NiCd battery’s 2.4 V, so I figured truth in packaging required a new label:

Skil Cordless Driver – new label cutting

The process:
- Scan the original labels
- Blow out the contrast to make binary masks
- Trace into vectors with LightBurn, simplify & clean up
- Add targets for Print-and-Cut
- Save as SVG, import into GIMP, lay out text, print
- Cut the outlines
The labels have laminating film on the top and craft adhesive on the bottom, both of which cut neatly and look pretty good:

Skil Cordless Driver – lithium in action

The alert reader will note the 4+ V from a fully charged lithium cell exceeds the 2.4+ V from fully charged NiCd cells, which accounts for the very bright incandescent headlamps. I figure 4 is roughly equal to 2.4, for large values of 2.4: the driver ticks along at 170 RPM instead 140 RPM.

I measured the torque using a double-ended hex bit in a torque screwdriver, with the torque setting cranked up until the driver just barely clicked it over.

I took the liberty of filing the raised “2.4 V” off the hinge covers and adding tidy retroreflective disks:

Skil Cordless Driver – hinge cover

I briefly considered adding “3.7 V” (because “4.2 V MAX” wouldn’t fit) in laser-cut PSA vinyl, but it was getting late.

Now I can screw things up in style …
2023-12-01
Bobbin Rock: Bigger and Tighter

While loading bobbins for her next quilt project, Mary found another one that just wouldn’t fit on the winder:

Bobbin with polishing rock

Knocking the rock out of the bore required a pin punch and more than a gentle tap, but it eventually left without damage. The little stick in the slot looked organic, although it vanished without a trace during the operation.

I originally thought the bobbin factory’s final vibratory polisher used walnut shells, but the evidence certainly suggests ordinary gravel!

2023-11-27
Kitchen Sink O-ring Seat Polishers

My long-running battle with the American Standard kitchen sink O-rings continues, but this time I tried polishing the seats with a strip of 3M 2000 grit sandpaper:

Sink O-ring seat polisher – overview

Although it’s technically sandpaper, the effect is more like lapping than sanding and the O-rings now ride on a very smooth surface.

The knurled half-ring is ¼-inch = 6.3 mm acrylic with an ID precisely fitting the pillar + sandpaper:

Sink O-ring seat polishers

The one on the right has an OD matching the surface inside the spout, but it turned out to be easier using fingertips, even if that isn’t quite how one should do lapping.

The LightBurn layout shows the “knurls” are half-circles either added or subtracted from the arcs, as LightBurn’s Circular Array tool is my copilot:

O-ring Polishers – LB layout

You’ll want to measure the ID and OD of your sink faucet, as well as the thickness of your sandpaper, before making make your own.

Imagining / laying out / building those took less time than writing this up; I loves me some quick laser cutter action.

2023-11-24
Hiatus

The sellers have accepted our offer on their house, so over the course of the next couple of months we’ll be moving, then selling this place. Having begun dismantling and packing the contents of the Basement Shop, Laboratory, and Warehouse, my blog-worthy activities will grind to a temporary halt.

Should you or anyone you know be interested in moving to the trendy Hudson Valley region, we have a conveniently located property with a shop-ready basement:

2108-2110 New Hackensack Rd – Streetview 2023-08

Maybe we can make a deal …

2023-11-13
CD / DVD Coasters: Foam vs. Cork Backing

Up to this point, I’d been making coasters with a layer of cork on the bottom, held in place with wood glue (for MDF or plywood tops) or an adhesive sheet (for acrylic or glass). Doing that with a CD produced the bottom coaster:

Laser cut CDs – Foam vs MDF-cork backing – detail

Although the Mariner’s Compass pattern looks like it extends over the edge, you’re looking through the transparent polycarbonate at the deep pits burned nearly through the entire disc at the corners of the triangles where the laser head slows.

Although the MDF layer makes the coaster exceedingly stiff, it also makes it entirely too thick and much too fiddly to assemble.

The top coaster is a Guilloche-patterned CD stuck to an EVA foam disk with an adhesive sheet. A small foam disk fills the hub hole and, not incidentally, covers the adhesive that would otherwise be exposed:

Laser cut CDs – Foam coaster backing

It’s stiffer than I expected and works well unless the mug / glass / cup has a wet bottom. Alas, the small channels cut into the CD’s surface fill up with the liquid sealing the coaster to the mug, so it sticks firmly and follows the mug upward off the table.

But they’re kinda pretty, inexpensive, and easy to assemble, which counts for something.

2023-11-10
CD / DVD Data Destruction: Fixturing

Cutting an array of 120 mm holes in chipboard produces a fixture for wrecking CDs:

Laser-engraved CD fixture – loaded

In addition to the obvious cutouts, the fixture has four corner targets:

CD 5×3 Fixture

Which you use with LightBurn’s Print-and-Cut alignment:

Laser-engraved CD fixture – alignment

With fifteen Guilloche swirly patterns imported and snapped into the template and the template aligned to the fixture, Fire The Laser:

Laser-engraved CD fixture – legend

The whole process takes a bit under 25 minutes:

Laser-engraved CD fixture – complete

Which produces a stack of glittery proto-coasters:

Laser-engraved CD fixture – results

Although they’re all pretty-like, turning them into Real Coasters requires a cork base, MDF in the middle, wood glue, and adhesive sheets, all of which seems entirely too much like work.

There ought to be an easier way …

2023-11-09
Guilloche Generator: Now With Layers & Colors

Tweaking the GCMC Guilloche generator to define colors for the SVG layers produces a pattern ready for LightBurn:

Guilloche – SVG layer colors

The blue layer runs at 300 mm/s at 10% PWM to carve trenches all over the CD / DVD surface, which should render it unreadable:

Laser cut CDs – Guilloche patterns

The laser runs much faster than a drag knife or a diamond engraving tool!

The reddish layer uses Dot mode to draw the legend around the hub:

Laser-engraved CD – legend detail

The characters are 1.5 mm top-to-bottom, with dots just under 0.2 mm diameter on 0.2 mm centers.

Stipulated: there’s no real point to annotating a CD that you’re wrecking, but the code was already there, so why not?

So the overall workflow involves generating an SVG image, importing it into LightBurn with those layers set up with the appropriate cut parameters, using the Three-Point Circle Center Finder tool to align the pattern with the CD, then Fire The Laser. Alignment stops on the laser platform eliminate the need to realign every pattern, so it boils down to running the generator script enough times, importing a batch of patterns, then snapping each one into place and cutting it.

They’re kinda pretty, in the usual techie way:

Laser cut CDs – Guilloche patterns

I have a lot of scrap discs, some ideas of optimizing the process, and a general notion what to do with the prettier results.

The GCMC source code and Bash driver script as a GitHub Gist:

2023-11-08