By turns: tinker, engineer, husband, author, amateur raconteur, recumbent cyclist, father, ham radio geek. So many projects, so little time!


Engraving Guilloché Patterns

Flushed with success from engraving a hard drive platter for the 21HB5A tube, I bandsawed an acrylic square from a scrap sheet and unleashed the diamond drag bit on it:

Guilloche 540237875 - engraved at -0.50mm
Guilloche 540237875 – engraved at -0.50mm

That’s side-lit against a dark blue background. The long scratch and assorted dirt come from its protracted stay in the scrap pile.

If you look closely, you’ll see a few slightly wider loops, which came from a false start at Z=-0.1 mm.

Engraving at -0.5 mm looked pretty good:

Guilloche 540237875 - engraved at -0.50mm - detail
Guilloche 540237875 – engraved at -0.50mm – detail

Despite an angular resolution of 2°, the curves came out entirely smooth enough. The gritty scratchiness resulted in a pile of chaff covering the engraved area; perhaps some oil or lube or whatever would help.

Rescaling the pattern to fit a CD platter worked fine, too:

Guilloche 540237875 - CD engraving
Guilloche 540237875 – CD engraving

Polycarbonate seems to deform slightly, rather than scratch, leaving the final product with no chaff at all:

In this case, the doubled lines come from the reflection off the aluminized lower surface holding all the data.

That CD should be unreadable by now …


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Squirrel Exploration

We spotted a motion twitch outside and finally figured out what was going on:

Squirrel in rotten branch hole - 1
Squirrel in rotten branch hole – 1

There must be something yummy down inside that branch scar, but you gotta keep checking your six:

Squirrel in rotten branch hole - 2
Squirrel in rotten branch hole – 2

Where’s a hawk when you need one?

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Collet Pen Holder vs. Cheap Refills

The three collet pen holders I got a while ago came with ink cartridges:

Collet pen holder
Collet pen holder

So I bought three bucks worth of a dozen pens to get pretty colors, whereupon I discovered they didn’t fit into the collet. Turns out the locating flanges aren’t in the same place along the cartridges:

The flanges on the top cartridge have been shaved down perilously close to the ink, but it now fits into the collet.

Bonus: a dozen fairly stiff springs that are sure to come in handy for something!


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Makergear M2: Z-Axis Platform Sensor Switch, Replacement Thereof

After nearly four years of dangling a bare millimeter above the nozzle, the lever on the relocated Z-Axis switch finally snagged a stray thread and got bent out of shape. I un-bent it, but finally decided it was time to get more air between the nozzle and the switch actuator.

The small shim reduces the actuation distance:

file:///mnt/bulkdata/Cameras/2019/Shop Projects/Makergear M2/Z-Axis Switch/IMG_20190204_185300 - M2 Z-Axis - microswitch exterior
file:///mnt/bulkdata/Cameras/2019/Shop Projects/Makergear M2/Z-Axis Switch/IMG_20190204_185300 – M2 Z-Axis – microswitch exterior

Prying the ends outward with a thumbnail releases a pair of snaps and the cover pops off to reveal the innards:

M2 Z-Axis - microswitch interior
M2 Z-Axis – microswitch interior

The spring-loaded innards will launch themselves into the far corners of your shop, so be gentle as you slide the lever out and reinstall the side plate with a pair of clicks.

I filed the screw holes in my homebrew brass angle plate into slots, so as to get some adjustability, remounted the switch on the X-axis gantry, and tuned for best clearance:

M2 Z-Axis - bare microswitch vs nozzle
M2 Z-Axis – bare microswitch vs nozzle

It looks a bit more canted than it really is.

There’s about 1.6 mm of Z-axis distance between the nozzle and the switch, which should suffice for another few years.

The view from the front shows a slight angle, too:

M2 Z-Axis - activated
M2 Z-Axis – activated

There’s a millimeter or so below the nuts holding the X-axis linear slide in place, because the original 18 mm M3 SHCS are now 16 mm long (having shotgunned the metric SHCS and BHCS situation some time ago) and the washers are gone.

They’re all nylon lock nuts except for the one just to the left of the switch, providing barely enough clearance for the Powerpole connectors on the hotrod platform:

M2 Z-Axis - platform connector clearance
M2 Z-Axis – platform connector clearance

With the nozzle off the platform to the far right side, Z-axis homing proceeded normally. Manually jogging to Z=+5.0 mm left 2.6 mm of air under the nozzle, so I reset the offset in EEPROM to -2.4 = (2.6 – 5.0) mm:

M206 Z-2.4

The first calibration square came out at 2.91 mm, so I changed the offset to -2.3 mm, got a 2.80 mm square with a firmly squished first layer, changed it to -2.5 mm, and got a 3.00 mm square for my efforts.

An array of five squares showed the platform remains level to within +0.05 / -0.07 mm:

M2 Platform Alignment Check - 2019-02-06
M2 Platform Alignment Check – 2019-02-06

I defined it to be Good Enough™ and quit while I was ahead.

The bottom two squares in the left pile have squished first layers. The rest look just fine:

M2 Z-Axis - switch offset calibration squares
M2 Z-Axis – switch offset calibration squares

The whole set-and-test process required about 45 minutes, most of which was spent waiting for the platform to reach 90 °C in the 14 °C Basement Laboratory.


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It’s Flat, Jim

Aaand this front-end loader will require more than the patch kit and CO2 inflator from my bike pack before it’s back in service:

Front-end loader with flat tire
Front-end loader with flat tire

The local yellow iron inventory spends most of the winter snoozing in shopping mall parking lots, waiting to clear the snowfall. It’s been a light year so far, which is fine with me.


Cart Corral Reassembly

Apparently, cart corrals last about four years and, with this refresh, the assemblers got it right:

Improved WalMart cart corrals
Improved WalMart cart corrals

All the white-on-blue marker signs up on the poles seem to be top-side-up, too.

Of course, not many people bother returning their carts to the corrals, but the bewilderment factor should be lower now.

And, yes, the previous mis-assembly remained uncorrected. I can’t take credit for the replacement, even though it happened during my adminstration …


Home Key Tactile Bumps

It seems I do more typing than the good folks at Kinesis expected:

Kinesis keyboard - worn tactile bump
Kinesis keyboard – worn tactile bump

In round numbers, the keyboard is all of two years old and that little ridge is pretty much history.

The ultimate fix will likely involve a dab of epoxy, but a duct tape snippet should show me how much of a bump my fingers need to find the home keys without conscious thought:

Kinesis keyboard - tape bump
Kinesis keyboard – tape bump

Early returns suggest one layer isn’t quite prominent enough; some iteration will be in order.

And, yeah, I should yank the keycaps for some deep cleaning.