Kenmore 158: Foot Pedal Foot Bushings

As you’d expect, the soft feet on the bottom of the Kenmore Model 158 sewing machine’s foot pedal control turn into hard buttons after a few decades. The OEM feet have mushroom tops that push through holes in the case and latch in place; of course, none of the rubber feet in my collection match the hole diameter or case thickness.

No problem! Design a bushing that fits the case hole and passes a 4-40 screw:

Speed Control Foot Bushing
Speed Control Foot Bushing

Then print up a handful, add screws to fit the rubber feet, and top off with nuts:

Kenmore 158 - pedal foot bushing - detail
Kenmore 158 – pedal foot bushing – detail

Installed, with the screws cropped to a suitable length, they look about like you’d expect:

Kenmore 158 - pedal foot bushing - interior
Kenmore 158 – pedal foot bushing – interior

Turns out that the springs supporting the foot pedal rest in those pockets, so the bushing reduces the spring travel by a few millimeters. The springs aren’t completely compressed with the pedal fully depressed, so it’s all good.

The OpenSCAD source code:

// Kenmore Model 158 Sewing Machine Foot Control Bushings
// Ed Nisley - KE4ZNU - June 2014

//- Extrusion parameters must match reality!
//  Print with 2 shells and 3 solid layers

ThreadThick = 0.20;
ThreadWidth = 0.40;

HoleWindage = 0.2;			// extra clearance

Protrusion = 0.1;			// make holes end cleanly

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

// Dimensions

Stem = [2.5,5.7];			// through the case hole
Cap = [3.0,10.0];			// inside the case

LEN = 0;
DIA = 1;

OAL = Stem[LEN] + Cap[LEN];

ScrewDia = 2.8;				// 4-40 generous clearance

// 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])


// Build it!


difference() {
	union() {
		PolyCyl(ScrewDia,OAL + 2*Protrusion,6);

A Pleasant Ride, With Turtle

It was not, however, a pleasant turtle:

Snapping Turtle on DCRT - 2014-06-04
Snapping Turtle on DCRT – 2014-06-04

That’s a fairly large snapping turtle in the middle of the Dutchess Rail Trail, between Morgan Lake and the Violet Avenue tunnel.

Snappers can move just under the speed of light for about a foot in order to latch onto you, but they’re not quite as fast while turning around: always pass to their rear. You do not attempt to save them from their folly at being in the middle of the road / trail / driveway: they have absolutely no patience with meddlers.

Turtles lay eggs around this time of year, which means they’re on the move, which means they cross roads, which means they get mashed. We’ve seen maybe half a dozen smashed turtles on our usual routes.

Quite some years ago, we found one of its relations in the flower garden beside our house, where it climbed at least 18 inches of vertical concrete block to see what was inside. It was about two feet long, jaws to tail, and obviously a survivor:

Snapping Turtle on wall
Snapping Turtle on wall

Those missing plates probably didn’t help its attitude in the least.

It eventually klonked down to the driveway without our assistance:

Snapping Turtle on driveway
Snapping Turtle on driveway

After a pause for gimbal unlocking and compass recalibration, it ambled off toward the Mighty Wappingers Creek. The wall gets much shorter to the right, which is likely where it climbed up.

We wished it good hunting …

Neither turtle was radio-active.

Writing Too Much

Being that type of guy, I make a local backup of this blog, using the Export function that normally serves to migrate blogs from to a self-hosted WordPress site. WordPress handles the disaster-recovery backup just fine, but cloud-based Internet companies have a tendency to just vanish without too much warning (Everpix and Code Spaces come to mind), so having my blog’s verbiage where I can touch it gives me a warm, fuzzy feeling.

Anyhow, the most recent export failed completely, whereupon I filed a support request:

My irregular backup involves exporting my blog, which has worked up to this evening, and tucking it away. Alas, it dies with the cryptic message This webpage is not found

Clicking More reveals:

No webpage was found for the web address: [... huge URL snipped...]


[… snippage …]

Can you get Export working again?

The response included the usual reboot-that-sucker advice:

[…] If you have problems next time you export your site, try clearing your browser cache and cookies and redoing the export. […]

But shaking the dice never really works:

OK, I’ve done that with three different browsers: Chromium, Firefox, and Pale Moon.

I’ve run Firefox in Safe Mode with all add-ons disabled, flushed everything, and the export function fails the same way.

The file name you gave me does not resemble the file name / URL / whatever presented to my browser.

That suggests the hole is not in this end of the boat.

Which forced a bump to Level 2:

[…] I’ve been discussing this with our developers and it seems the problem is that your export file it too large. We are hoping to fix this so that it won’t be an issue for you in the future but for the time being, you will have to export date-ranged posts. […]

I realise this isn’t ideal but it’s just a temporary workaround until this becomes a working feature in the not-too-distant future. I don’t have a date of completion at this stage.

Translation: “It’s like that and that’s the way it is.” When there’s no “date of completion”, that means the project is not on their calendar, which means they’ll never get around to doing it. A later conversation suggests that maybe August is the target date; we shall see.

So, how big is your blog, Ed?

The most recent backup export XML file weighed in at 28 MB, which doesn’t seem all that large by contemporary standards. Bear in mind that the file doesn’t include any of the 4300 images that occupy just under 1 GB (of the 3 GB one gets without buying a “media upgrade”).

It turns out size doesn’t matter:

It’s not the size of the file that is causing problems but rather the number of posts and media files. There are over 2000 posts and over 4000 media files.

I cannot imagine that those limits are held in 11 or 12 bit binary fields, but that would explain everything.

Apparently, the WordPress designers never expected anybody to produce one post a day, every day since late 2009. I’m certain I’m not the most prolific blogger on, but perhaps I’m the only one who’s ever tried to export the results …

Installing a Smooth-head Screw

A screw (*) fastens the capacity reduction block to the magazine’s interior floor plate:

Browning Hi-Power magazine - block detail
Browning Hi-Power magazine – block detail

It started as a normal M3x0.5 socket-head cap, but I reduced the diameter and turned off the socket to fit the existing hole in the exterior floor plate:

BHP floor plate screw - disk head
BHP floor plate screw – disk head

The head was just barely too large for the largest of my pin vises. Drat!

The easiest way (for me, anyhow) to install that screw into the epoxy-loaded block started by dropping it into what seems to be a shim-punching tool:

Base screw in alignment block
Base screw in alignment block

It’s in the left hole of the top front row: talk about protective coloration, eh?

Then capture it in one of the Sherline’s drill chucks:

Base screw in Jacobs chuck
Base screw in Jacobs chuck

Which makes it trivially easy to turn right into the nut brazed to the floor plate and the epoxy inside the block. When the epoxy cures, the screw, nut, floor plate, spring, and block become one solid unit.

That punch block came with the lathe tooling, made for some special purpose long lost in history. It comes in handy all the time for other jobs, though, so I think it’s still happy.

(*) The pictures are staged recreations; I was cleaning off the bench and unearthed the spare screws.

USB Micro-B Adapters

The Sony HDR-AS30V camera has a USB Micro-B jack. One might think all three of these cables / adapters should work:

USB Micro-B adapters
USB Micro-B adapters

But no:

  • The blocky Mini-to-Micro adapter on the top has no data lines
  • The Mini-to-Micro adapter cable works
  • The lower cable produces dependable disconnects

There is, of course, no way to determine any of that, except by trying each one to see what happens; the product descriptions diverge from the truth in myriad ways.

The camera came with a Micro-B cable that undoubtedly worked, but you try keeping track of one particular USB cable amid all the others.

More Quilting Pin Caps

Pinning the top of Mary’s latest quilt used more than 1600 pins: three boxes of specialized quilting safety pins, plus straight quilting pins tucked into all the 3D printed / silicone filled caps. Less than a quarter of the quilt top fits on the table:

Quilt top with pins
Quilt top with pins

Although Mary doesn’t need them right now, I made another batch of 100 caps for her next project:

Quilting pin caps - 4 x 25 - on platform
Quilting pin caps – 4 x 25 – on platform

I tweaked the OpenSCAD source to build a 10×10 array:

Quilting Pin Cap - 10x10 array
Quilting Pin Cap – 10×10 array

But it turns out that a 5×5 array of caps, duplicated four times, works out better:

Quilting Pin Cap - 5x5 array
Quilting Pin Cap – 5×5 array

Slic3r takes far longer to process the larger array than to make four copies of the smaller array.

Half an hour later, they’re ready for silicone fill. In retrospect, natural PLA wasn’t a good choice for this job: there’s no way (for me) to take a picture of translucent silicone in crystalline PLA atop waxed paper on a white cutting board under fluorescent light…

On the upside, however, you can see exactly how far the pin goes into the cap:

Quilting pin in translucent cap
Quilting pin in translucent cap

Makergear M2: Heating Times

With the platform and extruder starting at the 19.5 °C = 67 °F Basement Laboratory ambient …

The extruder takes 1 minute to reach 175 °C, overshoots to about 180 °C, crosses 175 °C going downward at 1:30, then gets up to 174 °C again at 3:15. I ran a PID tuning session quite a while ago with inconclusive results. Reducing the initial overshoot would probably increase the time-to-get-ready, with no net improvement.

The platform, which isn’t the stock Makergear hardware, requires 3:30 to reach 69 °C, just under the 70 °C target, at which point it’s ready to start. There’s no insulation under the PCB-trace heater, but some previous tinkering implies that running bare doesn’t make much difference, particularly with a fan blowing on the top surface of the glass.

M2 - Improved HBP - bottom view
M2 – Improved HBP – bottom view

The modified platform runs from a 40 V supply with an initial power of 250-ish W at ambient. A quick measurement at 75 °C during a print:

  • 40 V @ 5.8 A = 230 W peak
  • 10 s on / 30 s off = 25% duty cycle
  • 230 W × 0.25 = 58 W average

Remember that’s with an outboard SSR to unload the RAMBo’s MOSFET.

By and large, the M2 is ready to print in under 5 minutes from a standing start, which is just about enough time to spritz hair spray on the platform, load the G-Code into Pronterface, and so forth and so on.