Reversible Belt Buckle: Setscrew

The post in my reversible belt buckle popped out again, a year after punching it back in place, so it’s time to do a better job.

Grab the buckle in the Sherline vise, center on the post hole, and drill a #38 = 2.58 mm hole:

Reversible Belt Buckle - cross drilling
Reversible Belt Buckle – cross drilling

Tap it M3×0.5, clean out the hole, tap the post + spring back in place, dab threadlocker on the shortest M3 setscrew from the assortment, snug down on the post, and reinstall the belt:

Reversible Belt Buckle - M3 setscrew installed
Reversible Belt Buckle – M3 setscrew installed

Looks like it grew there, doesn’t it?

Now, as my buddy dBm will remind me, the real problem is too much weight in the saddle, but this fix should move the symptoms elsewhere …

Tek Circuit Computer: Cursor Hairline Scraping

Engraving a PETG sheet with a diamond drag engraver on the Sherline and filling the scratch produces a good-looking hairline, but there’s a tradeoff between having the protective sheet pull the paint out of the scratch and having the crayon scuff the unprotected surface. This time around, I scribbled the crayon through the protective film, let it cure for a few days, then scraped the surface to level the paint and see what happens.

First, an unscraped cursor:

Tek CC - Cursor red lacquer - plain - overview
Tek CC – Cursor red lacquer – plain – overview

Peeling the transparent protective film:

Tek CC - Cursor red lacquer - plain - partial peel
Tek CC – Cursor red lacquer – plain – partial peel

The hairline is solidly filled:

Tek CC - Cursor red lacquer - plain - peeled
Tek CC – Cursor red lacquer – plain – peeled

Scribbling another cursor the same way, then scraping the protective film to flatten the shredded edges:

Tek CC - Cursor red lacquer - scraped - overview
Tek CC – Cursor red lacquer – scraped – overview

The hairline remains filled, but not as completely:

Tek CC - Cursor red lacquer - scraped - partial peel
Tek CC – Cursor red lacquer – scraped – partial peel

A closer look:

Tek CC - Cursor red lacquer - scraped - peeled
Tek CC – Cursor red lacquer – scraped – peeled

Scraping the crayon off the film removes a substantial amount of paint from the hairline, but, on the upside, the protective film does exactly what it says on the box and the PETG surface remains pristine.

Both hairlines are, at least eyeballometrically, Just Fine™ for their intended purpose.

Magnifying Desk Lamp Pivot Clamp: One More

For reasons not relevant here, I made another clamp for a magnifying desk lamp and mailed it off in a small box. A few measurements suggested all such lamps share a common design and similar parts, so I duplicated my previous attempt, with some improvements.

On the upside, the same scrap of aluminum plate I used for the previous clamp emerged from the stockpile and, after a session with Mr Disk Sander, sported two square & reasonably perpendicular sides:

Magnifying Lamp Clamp - squaring stock
Magnifying Lamp Clamp – squaring stock

Rather than rely on my original dimension scribble, I transfer-punched the hole location from my as-built clamp to the stock:

Magnifying Lamp Clamp - locating stem hole
Magnifying Lamp Clamp – locating stem hole

That’s a reenactment based on a true story: the actual punching happened on the bench vise’s anvil surface, with too many moving pieces supported & aligned by an insufficient number of hands.

Drilling the 5/16 inch hole required mounting the Greater Chuck on an MT1 taper adapter for the Sherline:

Magnifying Lamp Clamp - drilling stem clamp
Magnifying Lamp Clamp – drilling stem clamp

It’s normally on an MT2 adapter for the mini-lathe tailstock, where it handles drills up to 3/8 inch. For the record, the Sherline’s Lesser Check tops out at 1/4 inch and the Least Chuck at 5/32 inch.

Punch & drill the 4 mm cross hole for the clamping screw:

Magnifying Lamp Clamp - drill cross hole
Magnifying Lamp Clamp – drill cross hole

Grab the plate in a toolmaker’s vise, set up some casual guidance, and bandsaw right down the middle:

Magnifying Lamp Clamp - sawing clamp halves
Magnifying Lamp Clamp – sawing clamp halves

Bandsaw the outline to free the two halves from the stock, then clean up their perimeter:

Magnifying Lamp Clamp - rounded
Magnifying Lamp Clamp – rounded

Saw the clamp clearance almost all the way through to leave a protrusion, then file the scarred kerf more-or-less flat:

Magnifying Lamp Clamp - filing interior
Magnifying Lamp Clamp – filing interior

Do a trial fit in my lamp, which lacks the fancy brushed-metal finish of the remote one:

Magnifying Lamp Clamp - trial fit
Magnifying Lamp Clamp – trial fit

It holds tight and rotates well, so break the edges and shine up the outside to a used-car finish (“high polish over deep scratches”):

Magnifying Lamp Clamp - surface finish
Magnifying Lamp Clamp – surface finish

The inside remains gritty to improve traction on the lamp stem:

Magnifying Lamp Clamp - interior
Magnifying Lamp Clamp – interior

Declare victory, box it up, and away it goes!

Nissan Fog Lamp: RGB LED “Bulb”

After cleaning the fog lamp lens enough to be encouraging, I made an LED “bulb” from four WS2812 RGB pixels:

Nissan Fog Lamp - LED bulb standup
Nissan Fog Lamp – LED bulb standup

The small threaded hole has an M3 setscrew to let the brass post slide up & down to adjust the LED position inside the fog lamp’s reflector.

Despite my poor experience with the PCB-based WS2812 LEDs, the strip-mounted ones have been ticking along in the hard drive platter lamp basically forever, at least after I tamped down the heat problem.

The brass hex rod has plenty of thermal conductivity, particularly clamped into an aluminum disk connected more-or-less well to the fog lamp’s base.

Nissan Fog Lamp - RGB LED lamp
Nissan Fog Lamp – RGB LED lamp

The two short wires linking the two LED strips (the purple wire is data into the first LED) hold them in place around the hex, despite their desire to straighten out, pull free of their adhesive, and fall off.

The general idea was to put the LEDs at about the same level as the halogen bulb filament, thereby spreading enough light to fill the reflector housing:

Nissan Fog Lamp - LED vs halogen
Nissan Fog Lamp – LED vs halogen

I drilled a hole through the hex as a cable “conduit”, turned the end into a nice rod, then machined a stub of aluminum to fit:

Nissan Fog Lamp - parting off LED base
Nissan Fog Lamp – parting off LED base

A pair of slots milled along the sides of the aluminum disk fit the housing’s locating features:

Nissan Fog Lamp - LED bulb trial fit
Nissan Fog Lamp – LED bulb trial fit

Nissan used an elaborate spring latch to clamp the halogen bulb’s sheet-metal base in place, but its 50 mil wire didn’t have nearly enough give for my chunky aluminum disk. My version of a spring latch came from a length of 24 mil music wire, which definitely beats the epoxy I was planning to use.

Heat transfer seems to be a non-issue, as the LEDs get barely warm to the touch. Until they drop dead, I’ll assume it’s all good in there.

Two screws hold the lens in place, but the collision seems to have stripped their grip on the plastic and they didn’t un-screw:

Nissan Fog Lamp - lens retaining screw
Nissan Fog Lamp – lens retaining screw

Jamming a utility knife blade under the screw head and prying upward while turning the screwdriver persuaded them out of their sockets, after which the lens popped out of its form-fitted silicone gasket with surprisingly little effort:

Nissan Fog Lamp - reflector stains
Nissan Fog Lamp – reflector stains

The lamp spent a week or so beside the road, out in the weather, and shipped a few drops of rainwater through the rectangular hole under the spring latch anchor. Some delicate cotton-swab action removed most of the grime without too much damage, but the reflective film on those corrugations won’t ever be the same again.

Now it’s just a simple matter of software …

Tek Circuit Computer: Cursor Hairline Filling

Some cleanup and a fresh layer of double-sided tape gives the cursor milling fixture plenty of adhesion:

Tek CC - Cursor blank on fixture
Tek CC – Cursor blank on fixture

This time, I diamond-scribed three PETG cursors through the transparent protective film, with two / four / six passes:

Tek CC - Cursor hairline filling
Tek CC – Cursor hairline filling

It’s not a Purple Crayon, but it suffices for my simple needs.

Scribbling a (soft!) lacquer crayon over transparent plastic still scuffs the pristine surface around the engraved line, so I tried scribbling the six-pass cursor before peeling the film, as shown above. Unfortunately, the film shreds left around the line either prevent a clean fill or pull the paint out of the ditch as the film peels back:

Tek CC - Cursor lacquer fill
Tek CC – Cursor lacquer fill

Peeling the film and scribbling ever-so-gently left a more complete line, but, if you look very closely (perhaps opening the image in a new tab for more dots), you can see the scuffs left by the scribbles on either side of the line:

Tek CC - Cursor 2 4 6 scribes
Tek CC – Cursor 2 4 6 scribes

When seen from the other side against laminated decks, though, the scuffs pretty much vanish:

Tek CC - Classic Tek Logo vectorized - red hairline
Tek CC – Classic Tek Logo vectorized – red hairline

The red hairline isn’t historically accurate, but I like the way it looks.

Give me some (heavyweight matte) paper and a (lacquer) crayon, put me in a basement (shop), and I’ll be happy for days

PETG Diamond Drag Engraving Tests

The hairline on the second machined cursor looks pretty good:

Tek CC - Milled cursor - unlaminated bottom deck
Tek CC – Milled cursor – unlaminated bottom deck

Based on manually scratching some acrylic, the GCMC code retraced the hairline four times to help the Sharpie stick to the groove. Maybe fewer passes would be better?

Affix a PETG scrap to the milling fixture for some manual CNC action:

PETG - engrave through film
PETG – engrave through film

Just to see what happened, I made the first scratch through the protective film and, because it’s hard to tell which side is up, the scratch went through the white film.

Repeat several times with variations in number of passes & downforce:

PETG - engraving test - overview
PETG – engraving test – overview

Manual jogging FTW:

  • 2 passes, 300 g, through film
  • 2 passes, 300 g, no film
  • 1 pass, 300 g
  • 3 passes, 300 g
  • 4 passes, 300 g
  • 1 pass, 260 g
  • 1 pass, 330 g

A closer look through the PETG sheet, as you’d see finished hairline, with the scratches in the same order as above:

PETG - engraving test - detail grid
PETG – engraving test – detail grid

They may be easier to see against a blank background:

PETG - engraving test - detail plain
PETG – engraving test – detail plain

Or in a hairline’s natural environment:

PETG - engraving test vs Testors sample
PETG – engraving test vs Testors sample

The absolute best-looking line is at the top, with the diamond point scribing through the (white) protective plastic film.

Multiple passes average out the waves / glitches / irregularities, at the cost of broadening the hairline.

The bottom hairline suggests a single pass with more downforce produces a broader groove and a finer line of Sharpie ink at the bottom; the top appears more rounded and the bottom more ragged.

Doing one pass with enough pressure to cut through the thinner (?) transparent(-ish) film may produce a better overall result. This will require me to get the orientation right.

The Real Hairline in my K&E Deci-Lon slipstick is a smoothly engraved, neatly half-cylindrical, channel with a smooth thread of red (!) ink / paint / pigment laid along the middle. Obviously, my engraving hand is weak …

The nightmare scenario: engraving a smooth hairline groove, completely backfilling it with paint, sanding (that side of) the cursor smooth to leave the groove’s paint flush with the surface, then polishing the plastic back to full transparency. Even I agree that’s crazy talk, at least for a circular slide rule made with laminated paper decks.

Tek Circuit Computer: Cursor Fixture Adhesion

After removing debris, flattening the top surface, and generally paying more attention to detail, the PETG sheet has much better adhesion to the fixture:

Tek CC - Milled cursor - cleaned fixture
Tek CC – Milled cursor – cleaned fixture

This time, I traced the inside of a drag-knife cut cursor to extract the blank from the stock and, yes, used new double-sided tape under the lower white protective film on the PETG.

Fewer air bubbles means better adhesion:

Tek CC - Milled cursor - fixture adhesion
Tek CC – Milled cursor – fixture adhesion

Spinning the 1/8 inch end mill at about 5000 RPM produced finer swarf at the Sherline’s maximum 609 mm/min = 24 inch/min pace, with less uplift. I suspect Moah RPMs! would be even better, constrained by melting the plastic into heartache & confusion.

Scribe the hairline with the diamond tool, ease the finished cursor off the fixture, scribble Sharpie into the scratch, and wipe

Tek CC - Milled cursor - second try
Tek CC – Milled cursor – second try

It’s Pretty Good™ when seen against an un-laminated bottom deck drawn with a Pilot V5RT pen:

Tek CC - Milled cursor - unlaminated bottom deck
Tek CC – Milled cursor – unlaminated bottom deck

The diamond point tears a slightly gritty path through the PETG, which then looks a bit more granular than a real hairline. I’ve been using four passes for emphasis; perhaps fewer would be better.