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.

Tag: Improvements

Making the world a better place, one piece at a time

Prusa MK4 Camera Lighting
Although the Raspberry Pi camera has a good view of the Prusa MK4’s extruder, there’s not much light under there:

RPi Camera Mount – image

There’s also not much room for a lighting fixture on the printer where it must mount, so I modified a trio of nominally 12 V / 4 W COB LED panels:

Prusa MK4 – Extruder sidelight – COB LEDs

Their “4 W” rating seems aspirational, at best, as a 12 VDC supply pushes only 75 mA through the panel, so they tick along at 900 mW. If you expect cheap eBay / Amazon components to live up to their specs, dream on.

The modifications:
- Unsolder the pins
- Crunch off the surprisingly precise 27.4 Ω SMD resistor
- Clean up the rubble
- Wire the panels directly in series, ignoring their bridge rectifiers
The 15 LEDs on each panel are arranged in five parallel chains of three LEDs for a total forward drop of 8.3 V, so putting three panels in series works with the MK4’s 24 V power supply.

Stick them onto the MK4 power supply case with foam tape and wire them directly to the 24 V terminals:

Prusa MK4 – Extruder sidelight – installed

There’s very little clearance between the machine frame and the X Axis carriage on the threaded rod. Putting the LEDs in a 3D printed case and routing the wires lower on the column would be nice touches:

Prusa MK4 – Extruder sidelight – front view

The panels start at 30 mA when cold and drop to 25 mA as they warm up in the 63 °F = 17 °C Basement Shop. Each panel dissipates 250 mW: bright enough for the task, dim enough to avoid overpowering the camera’s limited dynamic range, and definitely within whatever power rating they should have.

Looking over the camera’s shoulder in normal shop lighting suggests it’s about right:

Prusa MK4 – Extruder sidelight – camera overview

A staged scene with the shop lights turned off:

Prusa MK4 – Extruder sidelight – low-light view

Call it Good Enough™ for the purpose.
2026-05-20
Prusa MK4 Camera Mount

Combining the Articulating Raspberry Pi Camera Mount with the Standardized Links and a few more bits & pieces from Printables made this happen:

Prusa MK4 – RPi camera installed

The camera will benefit from better lighting, but it has a great view of the proceedings and gets the job done:

RPi Camera Mount – image

The Standardized Link holes clear an M6 bolt, but the Thumb Remix models use M5×25 hex-head screws (the doc says M4) and they work fine. I printed the (turn-able) bolt knobs in blue PETG-CF to distinguish them from the (fixed) nut knobs, which really don’t need knurling.

The camera ball mount has a threaded socket for the original plastic screws, but the stem isn’t quite thick enough for an M5 insert. Heat-setting an M4 brass insert into the hole and epoxying an M4×25 hex-head screw into one of the Remix knobs worked fine.

One Snap Fit Cable Management Clip holds the ribbon cable to a link. I think the RPi can fit under the platform inside the MK4 frame, with another clip or two routing the cable below the mount and frame. Adding another layer to the foam foot pads may improve the clearance.

The mount attaches to the MK4 frame with a 3030 adapter and a 45° link on the top. If I were in the mood, I’d make the 3030 adapter link longer for enough clearance beyond the M4 socket-head cap screws to get a ball-end hex wrench in there.

The small figure on the platform is a Articulated Grim Reaper done in black and white as an MMU3 test.

Now I can keep an eye on the proceedings from the Comfy Chair …

2026-05-15
Prusa MK4 Headbed Insulation

Over the winter, my Prusa MK4 printer occasionally coughed up a MINTEMP error when its platform heater cannot maintain the 90 °C called for by PETG. I finally added a cardboard insulating layer under the PCB heater:

Prusa MK4 Headbed – cardboard insulation

Yes, the blue tool layer rectangle marking the centers of the corner cutouts is offset 2.5 mm to the left:

Heatbed Insulation – LightBurn layout

The layout is not symmetric, because Prusa wanted to prevent you from installing the PCB incorrectly, so I needed three tries to get it right.

The alert reader will note the lack of the front-corner chamfers in the picture letting your fingers get under the corners to remove the steel sheet. I cut ’em off with a utility knife and you get the benefit of hindsight.

Whether this minimal insulation will solve the problem shall remain unknown until the coldest days of next winter, but eliminating drafts around the thermistor taped to the bottom of the PCB can’t possibly be a Bad Thing™.

The LightBurn layout exported to an SVG image as a GitHub Gist:

Loading
Sorry, something went wrong. Reload?

Sorry, we cannot display this file.

Sorry, this file is invalid so it cannot be displayed.
Viewer requires iframe.

view raw Heatbed Insulation – LightBurn layout.svg hosted with ❤ by GitHub

2026-05-14
House Sparrow vs. House Wren vs. Entrance Reducer

A friend gave Mary a small-bird birdhouse, which immediately attracted the attention of a pair of House Wrens:

Bird House entrance reducer – wren exiting

The vertical black bar is a DIY Birdsaver cord.

The entrance hole was 1-½ inch ⌀, a bit larger than the 1 inch ⌀ preferred by wrens and entirely suitable for the pair of House Sparrrows who also took an interest in the property:

Bird House – sparrow inside

This led to considerable discussion and displays of outright hostility:

Bird House entrance reducer – wren vs sparrow

Sparrows and wrens disagree on nestbuilding materials, with the wrens hauling twigs into the box and sparrows hauling them back out again.

Because wrens have better PR agents than sparrows, I intervened by taking the box apart:

Bird House – nest base sticks

Although I realize that’s a lot of work for a small bird, I dumped the contents off the patio and set about reducing the entrance hole:

Bird House – interior cleared

Because birds aren’t too fussy about looks, I sawed off half an inch of 1 inch (ID) CPVC pipe and glued it in the hole:

Bird House entrance reducer – interior glue

The outside looks marginally better:

Bird House entrance reducer – exterior glue

The sparrows continued to approach the hole at full throttle, deploying landing gear and speed brakes at the last possible moment:

Bird House entrance reducer – sparrow approach

But they no longer fit through the hole and eventually gave up trying. The wrens resumed hauling twigs, although we’re not certain they’ll finish the project, as birds tend to build several partial nests before selecting the final one.

We hope this will end on a happier note than last year’s Wreath Robins.

2026-05-13
Book Repair Tape vs. Serrated Cutter: Nope

An end-of-life roll of parchment paper contributed its serrated cutter bar as raw material for the Gridfinity Tape Dispenser:

Gridfinity Tape Dispenser – razor vs serrated blades

Those teeth look exactly like a tape cutter should look:

Gridfinity Tape Dispenser – serrated blade

It turns out that book repair tape bounces right off the pointy-but-not-keen edges, to the extent the tape did not cut at all, no matter how hard I tugged at any angle. Perhaps filing one side to make the teeth thinner would improve the results; given the cutter’s provenance it seems like putting lipstick on a pig.

The original razor blade continues to work fine, so I dropped the serrated cutter into the hollow under the tape roll against future need.

Book repair tape is tough stuff!

2026-05-12
Tour Easy: Bike Rack Tray Holder

Mary starts her garden plants at home, then hauls the trays to the garden in a plastic drawer strapped to the rack on her Tour Easy to avoid crushing the plants in the packs. I finally learned enough to make an adapter mating the drawer to the rack:

Bike Rack Tray Holder – in use

It’s made from four layers of laser-cut cardboard glued together with crossed corrugations for stiffness. I intended make a final version from glued-up plywood sheets, but it works surprisingly well as-is and I may just make another when this one wears out.

The rear view:

Bike Rack Tray Holder – rear view

The front has a cutout for the battery powering the rear camera, with the base height allowing enough meat above the battery:

Bike Rack Tray Holder – overview

The upright posts cradling the drawer may be too skinny for durability, which is why this is a prototype. The inner edges of the posts angle outward by a few millimeters to match the drawer’s mold draft.

Four feet locate the holder on the rack rails just ahead of the Ortlieb pack clips:

Bike Rack Tray Holder – rail detail

The rails are 8 mm ⌀ and the cutouts are 9 mm, because a little tolerance goes a long way. Similarly the tab widths just fit the available spaces beside the rail.

The two flat plates support the drawer and space the uprights to match the Ortlieb clips. I intended to mortise the plates into the uprights, but hot melt glue is wonderful stuff and the joint may outlast the cardboard. In retrospect, the outer edges of the plates should align with the inner sides of the uprights for maximum tidiness.

You don’t have that drawer and likely not the racks, so a picture of the LightBurn layout will give you the general idea for your hardware:

Bike Rack Tray Holder – LightBurn layout

Cut four copies of the uprights in two different orientations, glue them together, then do the obvious thing with the plates.

2026-05-11
Work Sharp Precision Sharpener: Clamp Support

Another Work Sharp Precision Adjust sharpener improvement from Printables:

WorkSharp – clamp support

Although the blade clamp is a snug fit in its socket, it has enough ~~stick-out~~ cantilever to move slightly even under minimal force from the diamond tools.

I added a thin cardboard shim, cut with a utility knife (!) and stuck on with a craft adhesive sheet, as the block was about half a millimeter upward with the clamp turned this-a-way and half a millimeter downward the other way. Your mileage / setup will certainly differ.

I like the sharpener, but it’s much fiddlier than I expected.

2026-05-05