Category: Machine Shop

Mechanical widgetry

HQ Sixteen: Stitch Regulator
The stitch regulator on our Handi-Quilter HQ Sixteen uses a pair of encoder wheels running along the tracks supporting the machine:

HQ Sixteen – stitch regulator sensor – rear

This must be HandiQuilter’s very first encoder version, because a ribbon cable connects the encoders to the control pod:

HQ Sixteen – stitch regulator sensor – rear

I stuck an adhesive cable clamp under the machine to rein in some of the slack, but the jank is strong with that arrangement and I must figure out a better arrangement with supple cable and better support. We’ll run this lashup for a while.

Anyhow …

The stitch regulator uses signals from the wheels to measure the distance the machine travels across the fabric and controls the motor speed to produce a fixed number of stitches per inch at that travel speed, as set in the control panel:

HQ Sixteen – display – stitch mode

Close inspection shows the LCD module came from an early 2000s mobile phone, but there’s no shame in repurposing cheap & readily available hardware.

When the stitch regulator is not active, the machine runs at a fixed speed set on the control panel:

HQ Sixteen – display – speed mode

The controller can set the speed between 100% to 10% of the motor’s 1500 stitch/min full speed, with 1% steps that seem too large on the low end and too small for the high end. Aiming my laser tachometer at a retroreflective tape snippet on the handwheel shows the machine runs at the correct fractions of its actual 1492 stitch/min = RPM.

The stitch regulator uses the same motor speed range, which sets corresponding limits on the maximum and minimum speeds across the fabric, with the ratio set by the stitch/inch value.

At the 10 stitch/inch setting Mary has been using, the travel speed range is:
- 15 inch/min = (150 stitch/min) / (10 stitch/inch)
- 150 inch/min = (1500 stitch/min) / (10 stitch/inch)
When you stop moving the machine, the controller will shut off the motor after a few stitches in the same place, which turns out to be convenient for tying off the end of a stitched line on a quilt. When you move too fast, the machine will top out at 1500 stitch/min while producing too-long stitches until the travel speed drops below 150 inch/min.

What’s not obvious is how slow those speeds are:
- 0.25 inch/s = 15 inch/min
- 2.5 inch/s = 150 inch/min
As an exercise, fire up the metronome app on your phone at one tick per second, then try drawing intricate patterns within those speed limits. You will inevitably move too fast, even without the soundtrack of a frantically accelerating motor topping out at 1500 RPM.

We think the surprisingly low upper speed limit accounts for much of the trouble Mary’s compadres report while using the stitch regulator.

After laying down a few square yards of practice quilt patterns while measuring the results and becoming accustomed to the sound and feel of the machine running at high speeds, Mary’s producing good results:

HQ Sixteen – stitch regulator – counting stitches

I definitely hit the knees in gratitude when the stitch regulator Just Worked™ after plugging it in, because that ribbon cable did not inspire any confidence whatsoever.
2025-04-07
Vole Trap Boxes: Deluxe Edition

The larger vole trap boxes didn’t survive the early spring rainfall, so we decided to upgrade the fleet with more durable boxes:

Vole Box – finished

I obviously need a larger light box.

The trap boxes come in 7 quart and 3.5 quart sizes, although we expect either will comfortably accommodate a single vole.

They’re made of polypropylene plastic eminently suited for laser cuttery, so I borrowed the holes from the cardboard box setup:

Vole Box – hole cutting

The clamps on the knife bars held the angle block and boxes in pretty much the same position, so I didn’t realign anything after figuring out a pair of magnets would hold the lid to the angle:

Vole Box – lid fixture magnets

The box side is slightly sloped, so I probably should have angled the block to tilt the lid, but this isn’t a precision job:

Vole Box – lid fixture

The white smudges on the lid come from vaporized polypropylene:

Vole Box – fume deposits

The body count thus far is just one field mouse, but the season is yet young.

2025-04-04
Potato Garage

Ordinary potatoes are photosensitive and turn green & bitter when exposed to light, so Mary stores them in a paper bag in the pantry. I recently re-found the cupcake / bread box previously used for battery storage and we decided it would make a great potato storage box:

Potato Garage – installed

It does look like a little garage with a roll-up door, doesn’t it?

The engraving on the top came from the New Garden Encyclopedia:

Garden Encyclopedia – Potatoes – engraving scan

The larger spud definitely has The Stink Eye! Also: tusks!

Threshold the scanned image, edit out a few blemishes, and engrave it atop the box:

Potato Garage – engraved

The result looks rather pallid, but this is not the place for fancy wood finishes.

The alert reader will note a purple sweet potato parked in there, but it’s close to the spirit of the thing.

2025-04-03

Floor Lamp Remote Control Holder

The remote control for the floor lamp across the Reading Room will never again wander away into the clutter:

Floor lamp remote holder - in use — Floor lamp remote holder – in use

The magnet in its back snuggles against a steel disk embedded in the holder:

Floor lamp remote holder - installed — Floor lamp remote holder – installed

A magnetic field visualization sheet revealed the magnet:

Floor lamp remote holder - magnet field visualization — Floor lamp remote holder – magnet field visualization

Extract the remote’s profiles with a contour gauge:

Floor lamp remote holder - pin contour gauge — Floor lamp remote holder – pin contour gauge

Trace the outlines and lay smooth curves around them with Inkscape:

Remote profiles - Inkscape curves — Remote profiles – Inkscape curves

They needed a slight lengthening to account for the gauge pin diameter & deflection, but this isn’t a precision project.

Do the same with a scan of the front face, import the curves into OpenSCAD, extrude them, create a solid model of the remote from their mutual intersection, then add a cylinder to punch the depression for the steel plate:

Floor Lamp Remote Holder - solid model - bottom — Floor Lamp Remote Holder – solid model – bottom

The chonky model corners stick out too far compared to the stylin’ curves on the real remote, but I made the holder shorter than the remote specifically to avoid fussing with such details.

Subtract the remote from a nicely rounded cuboid and knock out a cylinder for the pipe it’ll mount on to produce the holder:

Floor Lamp Remote Holder - solid model - Show view — Floor Lamp Remote Holder – solid model – Show view

I briefly considered a circumferential clamp around the pipe before coming to my senses and making the pipe diameter 2 mm larger to accommodate a strip of double-sided foam tape.

The magnet gets a ferocious grip on the plate and I defined the result to be All Good™.

The OpenSCAD source code and SVG paths as a GitHub Gist:

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view raw Floor Lamp Remote – outlines.svg hosted with ❤ by GitHub

	// Floor Lamp Remote Holder
	// Ed Nisley – KE4ZNU
	// 2025-03-29

	include <BOSL2/std.scad>

	Layout = "Holder"; // [Show,Build,Remote,Holder]

	BaseAngle = 30; // [0:50]

	/* [Hidden] */


	RemoteOA = [92.0,40.0,14.5];

	PoleOD = 16.0; // lamp pole

	MagnetOD = 20.0; // steel plate under magnet
	MagnetOffset = [11.0,0,-2.0];

	TapeThick = 1.2;

	HolderOA = [60.0,35.0,PoleOD/3 + 4.0 + RemoteOA.z/2];
	HolderRadius = 5.0;

	Gap = 10.0;

	//———-
	// Define shapes

	module RemoteBody() {
	union() {
	intersection() {
	fwd(RemoteOA.y/2) up(RemoteOA.z/2)
	linear_extrude(h=RemoteOA.z,center=true)
	import("Floor Lamp Remote – outlines.svg",layer="Top Outline");

	zrot(90) xrot(90)
	linear_extrude(h=RemoteOA.x,center=true)
	import("Floor Lamp Remote – outlines.svg",layer="End Outline");

	xrot(90)
	linear_extrude(h=RemoteOA.y,center=true)
	import("Floor Lamp Remote – outlines.svg",layer="Side Outline");
	}
	translate(MagnetOffset)
	cylinder(d=MagnetOD,h=RemoteOA.z,$fn=434);
	}
	}


	module Holder() {

	difference() {
	cuboid(HolderOA,anchor=BOTTOM,rounding=HolderRadius,except=TOP);

	down((PoleOD + 2TapeThick)(1/2 – 1/3))
	yrot(90)
	cylinder(d=PoleOD + 2TapeThick,h=2HolderOA.x,center=true);

	up(HolderOA.z – RemoteOA.z/2)
	RemoteBody();
	}

	}

	//———-
	// Build things



	if (Layout == "Remote")
	RemoteBody();

	if (Layout == "Holder")
	Holder();

	if (Layout == "Show") {
	color("White")
	Holder();

	color("Gray",0.75)
	up(HolderOA.z – RemoteOA.z/2 + Gap)
	RemoteBody();

	color("Green",0.5)
	down((PoleOD + 2TapeThick)(1/2 – 1/3))
	yrot(90)
	cylinder(d=PoleOD + 2TapeThick,h=2HolderOA.x,center=true);

	}

	if (Layout == "Build") {
	Holder();

	}

view raw Floor Lamp Remote Holder.scad hosted with ❤ by GitHub

2025-04-02

Laser Cutter: Letter Paper Storage Trays
Paper sheets must lay flat in storage, but it’s impossible to extract a single sheet from a tall pile. So I converted some moving boxes into stackable trays, each holding about a ream of paper:

Letter Paper Tray – installed

The starting point is a stackable Universal Box from boxes.py, with one end reshaped to become a tray. One Home Depot Large moving box provides enough 4.0 mm cardboard to make four trays, with one side of the box left over for future projects:

Letter Paper Storage Racks – LightBurn screenshot

The gray rectangle in the middle is the LightBurn workspace grid representing the 700×500 mm laser platform:

Letter Paper Tray – laser cutting

Contrary to the screenshot, I move all the layouts off to the side leaving the platform grid clear. The blue rectangles around the layouts represent the various box flaps / sides, so I can:
- Click a layout (which is grouped with the surrounding rectangle)
- Click Ctrl-D to duplicate it
- Hit P to put the duplicate at the middle of the platform grid
- Lay the corresponding cardboard sheet from that box part on the platform
- Align the layout with the cardboard using the camera
- Fire The Laser
Copious application of hot melt glue gloms all the pieces together.

I added support beams under the cardboard bottom plate:

Letter Paper Tray – bottom

A 2 mm arch in the top of those strips puts a camber into the sheet to counteract the natural sag from carrying five pounds of paper. The four trays at the far left lack that camber and cry out for a Mulligan.

Some day the Basement Shop™ won’t smell like a campfire.

The LightBurn SVG layout as a GitHub Gist:

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view raw Letter Paper Storage Racks – LightBurn layout.svg hosted with ❤ by GitHub
2025-04-01
Juki TL-2010Q Bottom Cover

Mary gave her Juki TL-2010Q sewing machine a deep cleaning & oiling, deputizing me to remove & replace the covers.

For the record, standing the machine on its left end is the least-awful way to get the bottom cover off and on:

Juki TL2010Q – bottom cover on end

You must remove all six of those husky screws; the black feet remain firmly stuck in their recesses. It’s not particularly stable in that orientation, so keep a firm hand on the top to prevent an expensive fall.

I laid it down for the rest of the session:

Juki TL2010Q – interior cleaning

She was unenthusiastic about wearing my headband light. Maybe next time.

It reassembled in reverse order and, after a brief tussle with the bobbin winder finger in the upper covers, runs smoothly.

2025-03-28
Metallic Layered Paper

With various iterations of the Letter sheet fixture in place, I made some layered paper “art” using metallic paper:

Metallic layered paper – Pyrotechnics block

That’s the Pyrotechnics quilt block pattern.

This is the RGBY Subpixel pattern:

Metallic layered paper – RGBY subpixels

The dotted rectangle in the lower left corner is the (turned off) front light in my low-budget light box and the glare in the upper left comes from the overhead basement LED strip lights.

AFAICT, “metallic paper” consists of shiny aluminum film bonded to heavy paper / cardstock, with transparent colored film bonded atop the aluminum. The sheet is, of course, highly reflective, which looks dark unless it’s reflecting a bright surface, like the well-lit Sewing Room ceiling:

Metallic layered paper – vs art paper

I made the bright Pyrotechnics block in the upper left with art paper that looks bright & cheerful in any lighting:

Metallic layered paper – art paper Pyrotechnics block

That’s the difference between specular reflectors and Lambertian reflectors.

I cut the metallic paper face-down in the fixture:

Pyrotechnics – metallized paper fixture

Although I’m underwhelmed by the metallic-layered-paper results, the stuff does make spectacular chaff:

Letter paper fixture – on knife bars

I should give our neighbor’s two-year-old lad a gift box …

2025-03-27