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

Bobbin Storage Trays

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:

Bobbin Storage Case – installed

They’re a matched set cut from 1.5 mm TroCraft Eco:

Bobbin Storage Case – cutting overview

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.

The well-stuffed URL specifying the tray:

http://festi.info/boxes.py/TypeTray?FingerJoint_angle=90.0&FingerJoint_style=rectangular&FingerJoint_surroundingspaces=0.5&FingerJoint_bottom_lip=0.0&FingerJoint_edge_width=1.0&FingerJoint_extra_length=0.0&FingerJoint_finger=2.0&FingerJoint_play=0.0&FingerJoint_space=2.0&FingerJoint_width=1.0&Stackable_angle=60&Stackable_bottom_stabilizers=0.0&Stackable_height=2.0&Stackable_holedistance=2.0&Stackable_width=4.0&Hinge_grip_percentage=0&Hinge_outset=0&Hinge_pinwidth=0.5&Hinge_style=outset&Hinge_axle=2.0&Hinge_grip_length=0&Hinge_hingestrength=1&CabinetHinge_bore=3.2&CabinetHinge_eyes_per_hinge=5&CabinetHinge_hinges=2&CabinetHinge_style=inside&CabinetHinge_eye=1.5&CabinetHinge_play=0.05&CabinetHinge_spacing=2.0&Lid_angle=90.0&Lid_hole_width=0&Lid_second_pin=0&Lid_second_pin=1&Lid_spring=both&Lid_style=rectangular&Lid_surroundingspaces=2.0&Lid_bottom_lip=0.0&Lid_edge_width=1.0&Lid_extra_length=0.0&Lid_finger=3.0&Lid_play=0.05&Lid_space=2.0&Lid_width=1.0&Click_angle=5.0&Click_bottom_radius=0.1&Click_depth=3.0&RoundedTriangleEdge_height=50.0&RoundedTriangleEdge_r_hole=2.0&RoundedTriangleEdge_radius=30.0&RoundedTriangleEdge_outset=1.0&Mounting_d_head=6.5&Mounting_d_shaft=3.0&Mounting_margin=0.125&Mounting_num=2&Mounting_side=back&Mounting_style=straight+edge%2C+within&HandleEdge_height=20.0&HandleEdge_hole_height=75.0&HandleEdge_hole_width=40%3A40&HandleEdge_on_sides=0&HandleEdge_on_sides=1&HandleEdge_radius=10.0&HandleEdge_outset=1.0&sx=21*7&sy=12*7&h=20.0&hi=10.0&outside=0&bottom_edge=s&top_edge=S&back_height=0.0&radius=0.0&gripheight=30&gripwidth=00&handle=0&thickness=1.65&format=lbrn2&tabs=0&debug=0&labels=0&reference=00&inner_corners=corner&burn=0.04

Which can now be specified as the biggest QR code I’ve ever seen:

Bobbin Tray – TroCraft Eco QR code

That makes my eyes hurt …

2023-03-01
Laser-Cut Envelope Opener

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.

2023-02-27
Tree vs. Guide Rail: Sheared Bolt

Spotted on a walk along the Mighty Wappingers Creek after a storm with plenty of gusty winds:

Tree-smashed guide rail

The tangle of branches and logs came from a tree that fell across the road from the far right side and put that crease into the guide rail. The vertical stump seems unrelated to that incident.

A bit of rummaging at the base of one post produced a victim:

Tree-smashed guide rail – sheared bolt – side

The impact produced enough force to turn the rail brackets into guillotine metal shears against the posts:

Tree-smashed guide rail – sheared bolt – end

It’s not a clean shear cut, which isn’t surprising under the circumstances.

An ordinary ½-13 Grade 8 bolt has a 17 k pound proof load: popping that bolt required a mighty oomf.

Memo to Self: stay indoors during windy storms!

2023-02-24
DIY CPAP Mask Liner
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 LightBurn SVG layouts as a GitHub Gist:

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2023-02-22
Shower Faucet Handle Rebuild & Tightening

The shower faucet handles have been getting looser, but once a decade seems reasonable. This time around, however, the setscrews had dug themselves so far into the splined plastic fittings that they had run out of thread:

American Standard Shower Handle rebuild – gouged setscrew sockets

Wipe out the crud, clean out what’s left with alcohol to encourage stick-to-it-ivity, and fill the cavities with JB Kwikweld epoxy:

American Standard Shower Handle rebuild – epoxy fill

When it cures, file a flat across the sockets:

American Standard Shower Handle rebuild – flatted

Reinstall in reverse order with a dot of NeverSeez on the setscrews for good measure.

Just so you don’t have to look it up, this is what the cold water faucet innards looked like a decade ago:

Shower faucet valve stem

Ought to be good for another decade, right?

2023-02-21
World War II Dog Tag Layout

Quite some time ago, I hammered out G-Code to engrave ersatz dog tags for a Cabin Fever demo:

Cabin Fever Dog Tag

A dozen years later, making a World War II dog tag is a whole lot easier:

John Q Public – WWII dog tag

Well, “easier” if you allow laser engraving in white-on-black Trolase using a font intended to mimic a typewriter.

Close enough, methinks.

Which comes from a simple layout:

John Q Public – WWII dog tag – LB layout

The outline traces a scanned image of my father’s tag, fitting a few hand-laid splines around the curves:

John Q Public – WWII dog tag – spline curves

I generated a random serial number based on my father’s draftee status (he was in his early 30s during his South Sea Island tour) and state of residence; my apologies to anyone carrying it for real. His blood type was A and (I think) the religion code marks him as “Brethren”, a common group in my ancestry.

Given the outline, various plastics, and a laser, other effects become possible:

WWII dog tag outline test

It might come in handy for something, someday.

The LightBurn SVG layout as GitHub Gist:

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2023-02-20
Lift Chair Foot Risers
The fuzzy felt feet on the lift chairs raised them enough to slide both floor lamp bases underneath with the backs in the upright state, but reclining the chair with the light more than halfway back along the side of the chair crunched the lamp base.

Rather than print taller fuzzy feet, which takes a long time, I knocked out two quartets of laser-cut risers:

Lift Chair Foot Riser – installed

They’re six layers of 3 mm MDF or plywood:

Lift Chair Foot Riser – assembled

The LightBurn layout makes one riser:

Lift Chair Feet Extenders – LB layout

The upper two discs become two rings and two pads, with the lower two disks forming the middle layers. The ring ID clears the chair foot and the pad OD fits into the existing printed fuzzy felt foot. The two cuts making that happen leave the thinnest imaginable ring of MDF in place.

The tiny circles cut holes for 11 mm snippets of 1.1 mm hard steel wire aligning the layers:

Lift Chair Foot Riser – locating pins

Assembly sequence:
- Tap two pins into a ring
- Butter the ring with yellow wood glue
- Slide the other ring over the pins
- Butter
- Slide a disk over the pins
- Drive a pin into a pad
- Butter
- Slide the other pad over the pin
- Butter
- Slide a disk over the pin atop the pads
- Butter one of the disks
- Slide the disks together over all three pins
- Tap all pins below their surface
Make two and clamp them together to ensure everything sticks firmly.

Repeat to make four risers

Install, recline, and enjoy not hearing a mysterious crunch from the lamp base.

The alert reader will note the 6 mm stack of two pads leaves a slight gap above the printed foot. Turns out the recess is 5 mm deep and I decided to just live with a 1 mm gap down there.
2023-02-16