Modified Quilting Foot: Speed Wrench Knob

The Nyloc nut atop that modified quilting foot requires more grip than fingers can provide:

Modified Darning Foot - in action
Modified Darning Foot – in action

The “precision” wrench I adapted to that nut works for small adjustments, but for larger ones it’s easier to take the foot off and spin this knob:

Quilting Foot Knob - knurling
Quilting Foot Knob – knurling

It has a hex opening in each end that fits the nut, with a through hole for the bolt. The top looks exactly like you’d expect:

Quilting Foot Knob - top
Quilting Foot Knob – top

The bottom needs a bit of support:

Quilting Foot Knob - bottom support
Quilting Foot Knob – bottom support

The solid model shows off the support in color:

Quilting Foot Knob
Quilting Foot Knob

The OpenSCAD source code doesn’t have many surprises:

// Quilting foot knob
// Ed Nisley KE4ZNU January 2013

use <knurledFinishLib_v2.scad>

//- Extrusion parameters must match reality!
//  Print with +1 shells and 3 solid layers

ThreadThick = 0.20;
ThreadWidth = 0.40;

HoleWindage = 0.2;

function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);

Protrusion = 0.1;			// make holes end cleanly

// Dimensions

KnobOD = 20.0;
KnobLength = 25.0;
KnobSides = 12;

DiamondLength = KnobLength/3;
DiamondWidth = DiamondLength/2;
DiamondDepth = 1.0;

NutOD = 7.0;				// across flats!
NutLength = 6.0;
ScrewOD = 4.0;

DoSupport = true;

// Useful routines

module PolyCyl(Dia,Height,ForceSides=0) {			// based on nophead's polyholes

  Sides = (ForceSides != 0) ? ForceSides : (ceil(Dia) + 2);

  FixDia = Dia / cos(180/Sides);

  cylinder(r=(FixDia + HoleWindage)/2,

module ShowPegGrid(Space = 10.0,Size = 1.0) {

  RangeX = floor(100 / Space);
  RangeY = floor(125 / Space);

	for (x=[-RangeX:RangeX])
	  for (y=[-RangeY:RangeY])


module Knob() {
	rotate(180/Sides) {
		difference() {
//			cylinder(r=KnobOD/2,h=KnobLength,$fn=KnobSides);
				PolyCyl(ScrewOD,(KnobLength + 2*Protrusion),6);
			translate([0,0,(KnobLength - NutLength)])
				PolyCyl(NutOD,(NutLength + Protrusion),6);
				PolyCyl(NutOD,(NutLength + Protrusion),6);

module Support() {
		for (Seg=[0:5]) {
			translate([0,0,(NutLength - ThreadThick)/2])
				cube([(NutOD - 1*ThreadWidth),
						(NutLength - ThreadThick)],

// Build them!



if (DoSupport)

Mary likes it… and thinks I’m being silly. She’s right, of course.

Forcing Pulseaudio DisplayPort Volume Initialization

It turns out that the audio-over-HDMI/DisplayPort channel which, for whatever reason, is the only way to get audio out of the Optiplex 980 with the big Dell U2711 monitor starts up AT MAXIMUM VOLUME! regardless of the GUI’s Pulseaudio mixer setting that’s diligently saved-and-restored across sessions. That makes a certain perverse sense, as the digital-to-analog converter & power amp live inside the monitor.

Manually adjusting the GUI mixer by one click, either up or down, forces the new setting out over the digital link to the monitor, after which the audio output corresponds to the mixer; I never remember that until just after some dipshit auto-play video lights up with a fanfare.

Setting the mixer to the same value doesn’t force an update, so the obvious solution (at least to me) of sending a fixed initial value doesn’t work; it’s optimized away. I think that’s why the initial update doesn’t happen: the stored volume is the same as the, ah, stored volume, so there’s no need to tell the monitor.

The automatic solution involves putting two more commands in my ever-growing ~/.config/

amixer -D pulse sset Master 26%
amixer -D pulse sset Master 1%-

That sets a rational level (which might be the same as the existing one from the previous session), then changing it by one tiny click to force the new value out to the monitor.

And then It Just Works…

Rounded Rectangles in OpenSCAD: Mold Positives?

A discussion on the OpenSCAD mailing list about making a rectangular solid with rounded edges having different radii eventually produced this delightful result:

Basic Rounded Cube
Basic Rounded Cube

Those guys make me feel dumb, because they’re generally solving problems I can’t even imagine, but I know what to do with this solution. One could slice it in half horizontally, emboss a height map defining a logo / picture into the top surface, print it out on your favorite 3D printer, maybe smooth / seal the surface a bit, define it to be a positive mold pattern, cast / pour flexible silicone around it, and get a negative mold for a pourable precious material such as, oh, chocolate.

You could make half a dozen of them, arrange them inside a suitable printed frame, pour the silicone, and get a multi-cavity mold for better manufacturing productivity.

The overall block lacks draft, because the problem it solves presumes you need a block of specific outside dimensions: it overlays three full-size rectangular blocks that define the dimensions. OpenSCAD constructs spheres such that they may be slightly smaller than the defined radius at the poles and, depending on their alignment, a face at the equator may reduce the outer dimension of a surrounding hull.

Given a sufficiently bendy silicone mold, you might not need any draft at all. If you do need draft and you don’t care about a very slightly undersized pattern, remove the internal blocks and increase the XY spacing of the lower four spheres by enough to make the draft come out right.

The grayscale logo / image should have nice smooth transitions that produce suitable draft for the fine details; a bare black-and-white image might not work well. Shallow is good, but that conflicts with 3D printing’s crappy resolution: 1 mm = 10 layers, tops. That might not matter in practice.

You’re supposed to temper the chocolate, but that’s probably more relevant for Fine Art molds.

The (slightly modified) OpenSCAD source code:

module rcube(size=[30, 20, 10], radius=[3, 2, 1], center=true)
	hull() {
		translate( center ? [0,0,0] : size/2 ) {

			for(x = [-0.5,0.5], y = [-0.5,0.5], z = [-0.5,0.5])
				translate([x * ( size[0] - 2*radius[0]),
						   y * ( size[1] - 2*radius[1]),
						   z * ( size[2] - 2*radius[2])])
					scale([radius[0], radius[1], radius[2]])


When I get around to doing molds, maybe I can remember what I was thinking…

Thing-O-Matic 286 Conversion: Slic3r Configuration

The Thing-O-Matic hardware isn’t up to the standards of, say, an M2, but, after all my tweakage, it’s Good Enough for most purposes. These Slic3r settings should provide a reasonable starting point to get it working the way it used to with its new controller.

The key extrusion dimensions:

  • 0.4 mm nozzle → 0.5 mm minimum thread width
  • 0.25 mm layer thickness

The speeds come from the old Skeinforge configuration, dialed back a bit for sanity:

  • 150 mm/s non-printing XY travel
  • 10 mm/s minimum printing speed
  • 20 mm/s first layer printing for better adhesion
  • 40 mm/s general printing
  • 60 mm/s infill

Some of the finer settings are completely arbitrary and everything requires tweaking, along with Marlin’s acceleration & jerk settings, for best picture.

The exported Slic3r configuration:

# generated by Slic3r 1.0.0RC1 on Fri Jan 17 11:25:02 2014
avoid_crossing_perimeters = 0
bed_size = 105,120
bed_temperature = 110
bottom_solid_layers = 3
bridge_acceleration = 0
bridge_fan_speed = 100
bridge_flow_ratio = 1
bridge_speed = 40
brim_width = 0
complete_objects = 0
cooling = 1
default_acceleration = 0
disable_fan_first_layers = 1000
duplicate = 1
duplicate_distance = 6
duplicate_grid = 1,1
end_gcode = ;---- end.gcode starts ----\n; TOM 286 - Al plates + Geared extruder\n; Ed Nisley - KE4ZNU - January 2014\n; Marlin with tweaks for Azteeg X3 with thermocouple\n;- inhale filament blob\nG91\nG1 E-5 F900\nG90\n;- turn off heaters\nM104 S0         ; extruder head\nM140 S0         ; HBP\n;- move to eject position\nG1 Z999 F1000   ; home Z to get nozzle away from object\nG92 Z115      ; reset Z\nG1 X0 F6000     ; center X axis\nG1 Y35          ; move Y stage forward\n;---- end.gcode ends ----
external_perimeter_speed = 50%
external_perimeters_first = 0
extra_perimeters = 1
extruder_clearance_height = 20
extruder_clearance_radius = 20
extruder_offset = 0x0
extrusion_axis = E
extrusion_multiplier = 1.00
extrusion_width = 0.50
fan_always_on = 0
fan_below_layer_time = 1
filament_diameter = 2.95
fill_angle = 45
fill_density = 0.15
fill_pattern = honeycomb
first_layer_acceleration = 0
first_layer_bed_temperature = 110
first_layer_extrusion_width = 0.50
first_layer_height = 0.25
first_layer_speed = 20
first_layer_temperature = 200
g0 = 0
gap_fill_speed = 30
gcode_arcs = 0
gcode_comments = 0
gcode_flavor = reprap
infill_acceleration = 0
infill_every_layers = 3
infill_extruder = 1
infill_extrusion_width = 0.50
infill_first = 1
infill_only_where_needed = 1
infill_speed = 60
layer_gcode =
layer_height = 0.25
max_fan_speed = 100
min_fan_speed = 35
min_print_speed = 10
min_skirt_length = 5
notes =
nozzle_diameter = 0.4
only_retract_when_crossing_perimeters = 1
ooze_prevention = 0
output_filename_format = [input_filename_base].gcode
overhangs = 1
perimeter_acceleration = 0
perimeter_extruder = 1
perimeter_extrusion_width = 0.50
perimeter_speed = 40
perimeters = 2
post_process =
print_center = 0,0
raft_layers = 0
randomize_start = 1
resolution = 0.05
retract_before_travel = 0.5
retract_layer_change = 0
retract_length = 2
retract_length_toolchange = 10
retract_lift = 0
retract_restart_extra = 0
retract_restart_extra_toolchange = 0
retract_speed = 60
rotate = 0
scale = 1
skirt_distance = 2
skirt_height = 1
skirts = 3
slowdown_below_layer_time = 15
small_perimeter_speed = 50%
solid_fill_pattern = rectilinear
solid_infill_below_area = 5
solid_infill_every_layers = 0
solid_infill_extrusion_width = 0.50
solid_infill_speed = 150%
spiral_vase = 0
standby_temperature_delta = -5
start_gcode = ;---- start.gcode begins ----\n; TOM 286 - Al plates + Geared extruder + Zmin platform sense\n; Ed Nisley - KE4ZNU - January 2014\n; Marlin with tweaks for Azteeg X3 with thermocouple\n;\n; Set initial conditions\nG21                 ; set units to mm\nG90                 ; set positioning to absolute\n;----------\n; Begin heating\nM104 S[first_layer_temperature]         ; extruder head\nM140 S[first_layer_bed_temperature]    ; start bed heating\n;----------\n; Home axes\nG28 X0 Y0 Z0\nG92 X-53.5 Y-58.5 Z115.0\n;----------\n; Initial nozzle wipe to clear snot for Z touchoff\nG1 X0 Y0 Z3.0 F1500     ; pause at center to build confidence\nG4 P1000\nG1 Z10                  ; ensure clearance\nG1 X39 Y-58.0 F10000    ; move to front, avoid wiper blade\nG1 X55                  ; to wipe station\nG1 Z6.0                 ; to wipe level\nM116                    ; wait for temperature settling\nG1 Y-45 F500            ; slowly wipe nozzle\n;-----------------------------------------------\n; Z platform height touchoff\n; Make sure the XY position is actually over the switch!\n; Home Z downward to platform switch\n; Compensate for 0.05 mm backlash in G92: make it 0.05 too low\nG1 X56.0 Y8.2 Z4.0 F6000     ; get over build platform switch\n;G1 Z0 F50                    ; home downward very slowly\n;G92 Z1.45                    ; set Z-min switch height\nG1 Z6.0 F1000                ; back off switch to wipe level\n;-----------------------------------------------\n; Prime extruder to stabilize initial pressure\nG1 X55 Y-45 F6000   ; set up for wipe from rear\nG1 Y-58.0 F500      ; wipe to front\nG91                 ; use incremental motion for extrusion\nG1 F2               ; set slow rate\nG1 E10              ; extrude enough to get good pressure\nG1 F4000            ; set for fast retract\nG1 E-2.0            ; retract\nG90                 ; back to absolute motion\nG1 Y-45 F1000       ; wipe nozzle to rear\n;----------\n; Set up for Skirt start in left rear corner\n; Compensate for Z backlash: move upward from zero point\nG1 X-50 Y55 Z0.0 F10000     ; left rear corner -- kiss platform\nG1 Z0.2 F1500       ; take up Z backlash to less than thread height\nG92 E1.0            ; preset to avoid huge un-Reversal blob\n;G1 X0 Y0\n;---- start.gcode ends ----
start_perimeters_at_concave_points = 1
start_perimeters_at_non_overhang = 1
support_material = 0
support_material_angle = 0
support_material_enforce_layers = 0
support_material_extruder = 1
support_material_extrusion_width = 0.50
support_material_interface_extruder = 1
support_material_interface_layers = 3
support_material_interface_spacing = 0
support_material_pattern = honeycomb
support_material_spacing = 2.5
support_material_speed = 60
support_material_threshold = 0
temperature = 200
thin_walls = 1
threads = 2
toolchange_gcode =
top_infill_extrusion_width = 0.50
top_solid_infill_speed = 50%
top_solid_layers = 3
travel_speed = 150
use_firmware_retraction = 0
use_relative_e_distances = 0
vibration_limit = 0
wipe = 0
z_offset = 0

2000 Toyota Sienna: Replacing the Bank 1 Sensor 2 Oxygen Sensor

Shortly after replacing the battery, the dreaded Malfunction Indicator Lamp popped on with a P0420 error code that, according to the Nice Man at Autozone, translates into “low catalytic converter efficiency”. A bit of diagnostic sleuthing reported that the most likely cause was an exhaust leak, followed by an out-of-calibration downstream oxygen sensor, followed by a bad converter. Internet lore has it that replacing the cat cracker is a dealer-only event (here in New York State, with a van sporting the California emissions package) that costs upwards of $2 k, which seems excessive for a 14-year-old van.

Actually, the most probable cause was replacing the battery: the brief power outage wipes out the stored performance data for the emissions control machinery. Because we make only short trips and it’s been bitterly cold, the algorithms may conclude the converter’s dead when it’s just a matter of measuring the variables under suboptimal conditions.

With all that in mind, after a peek under the van ruled out the exhaust leak, I decided to replace the oxygen sensor. All this happened during a week when the outdoor temperature hovered around 10 °F = -12 °C, but the forecast called for an atypical January day with a high of 55 °F = 13 °C; I might not get a second chance before the annual inspection came due in February.

The sensor is relatively cheap (about $70 at the local Autozone) and, entirely unlike Bank 1 Sensor 1, readily accessible on the tailpipe downstream of the cat cracker:

Sienna Bank 1 Sensor 2 - in place
Sienna Bank 1 Sensor 2 – in place

The OEM sensor cable runs in a sheath held to the chassis with a plastic clamp:

Sienna Bank 1 Sensor 2 - cable clamp
Sienna Bank 1 Sensor 2 – cable clamp

Jamming a small screwdriver into the clamp released the tongue and the sheath. The sheath vanishes into the van’s interior through a squishy rubber boot, with a crimped metal band joining the two:

Sienna Bank 1 Sensor 2 - floor boot
Sienna Bank 1 Sensor 2 – floor boot

Internet lore would have you believe you can replace the sensor without removing the front passenger seat, but it’s much easier if you remove the four bolts, disconnect the seat sensor, and lay the seat on its back:

Sienna Bank 1 Sensor 2 - interior connector
Sienna Bank 1 Sensor 2 – interior connector

More fiddly-diddly with the screwdriver under the van wrecked the band enough to separate sheath from boot, at which point deploying the BFW with the magic oxygen sensor socket showed that the anti-seize compound on the sensor’s thread worked as intended: after one oomph the sensor turned out by hand.

Then you just punch the boot through the floor and bring it all inside to splice new sensor onto OEM connector. Standardization is a wonderful thing; the sensor cable may use any one of eight color codes. The Toyota OEM sensor was a “Type B” that matches up with the Bosch replacement sensor thusly:

  • Heater = two black leads ↔ two white leads
  • Signal = blue lead ↔ black lead
  • Ground = white lead ↔ gray lead

Although the splice block has water-resistant seals, I figured putting it inside the van couldn’t possibly be a Bad Idea, so there it is, nestled snugly into the recess in the floor:

Sienna Bank 1 Sensor 2 - splice block
Sienna Bank 1 Sensor 2 – splice block

Picked up a nice new Autel AL519 OBD Code Scanner from the usual Amazon vendor, reset the trouble code, drove to-and-from Squidwrench (across the river, just barely far enough to reset the performance data), and so far it’s All Good. The motivation for getting my very own scanner, rather than returning to Autozone, is that the AL519 can do real-time graphing and data capture from various sensors, so I can perform Science! should the spirit move me.

The AL519 has a USB connection that appears as a USB serial device but, alas, the relentlessly Windows-centric host program won’t run under Wine.

Why Friends Don’t Let Friends Run Windows: Bad Gadgets

The Token Windows box (which runs the few programs that don’t get along with Linux) doesn’t get a lot of attention, but a recent update changed their stylin’ graphic CPU meter to something a bit less, mmm, smooth:

Win 7 - CPU Meter
Win 7 – CPU Meter

Searching for the obvious keywords turned up an explanation from Microsoft:

Windows Gadgets Have Been Discontinued - detail
Windows Gadgets Have Been Discontinued – detail

It seems they simply pushed an update that killed Gadgets, without explanation or warning.

Who could have anticipated that allowing random strangers to run their code on a desktop PC would lead to security problems?

Bent Tap: Huh?

The Shapeways bronze-infused stainless steel process reportedly produces objects so hard that they require carbide tooling, so I wasn’t too surprised when this magazine block rounded the threads right off a tap:

Browning Hi-Power magazine - steel block trial fit
Browning Hi-Power magazine – steel block trial fit

The tap turned up while I was clearing off the bench and, seeing as how the upper half of the threads weren’t ruined, I thought maybe I could at least get a bottoming tap out of it.

Step 1: snap off the damaged part. This should be easy, as tap steel tends to punish you when you’re not doing it right. So I grabbed the ruined section in the bench vise and gave the shank a stiff whack:

Bent tap
Bent tap

Now, that is not a nominal outcome

The tap came from a set of dubious provenance that’s conspicuously labeled: JUNK METRIC. I have no idea where it came from, as it’s slightly younger than dirt. There’s a Craftsman metric set in the same drawer with much better steel (yes, I’ve snapped a few taps) that I normally use; I figured if I was going to wreck a tap on that magazine block, I should wreck a junk tap.

Maybe that Shapeways stainless isn’t quite as nasty as it seems…