Archive for category Machine Shop

Electrolux Vacuum Cleaner: Cord Protection

The ancient (Came With The House™) Electrolux canister vacuum cleaner long ago lost the plastic bushing around the opening passing its retractable cord, which I’d long sworn to replace.  A recent trip around the Basement Laboratory paused near the recently relocated Box o’ Wire Loom & Braid, whereupon I snipped off a few inches of split loom and tucked it in place:

Electrolux Vacuum - cushioned cord cutout

Electrolux Vacuum – cushioned cord cutout

Looks and works better than before, anyhow.

The blue flap dangling off the back should latch over the exhaust port, but failed long ago when the latch tab eroded. I attempted a repair, which never worked quite right, and won’t get around to attempting another for quite a while.




Badger Propel Air Fittings: DIY Rubber Washers

Unlike ordinary bike tubes, Michelin ProTek tubes have a square-ish cross section:

Michelin Protek Max Tube - carton

Michelin Protek Max Tube – carton

So, having a defunct Michelin ProTek tube in hand, I cut, cleaned, and dissected a few inches, then punched out a set of (flat!) washers for the Badger Propel air fittings:

Badger 260 Propel fitting seals - inner-tube version

Badger 260 Propel fitting seals – inner-tube version

As with the cork version, they fit fine:

Badger Propel fitting - DIY rubber seal

Badger Propel fitting – DIY rubber seal

The picture is slightly fuzzy, because zooming a Pixel photo doesn’t magically create any new mmmm pixels.

I tested the washer with 45 psi air (the recommended maximum) and it holds the pressure fine. Better than a fouled ProTek valve, anyway.

Flushed with success, I preemptively replaced both OEM cork washers, an action which will surely come back to haunt me.




Michelin ProTek Max Tube: Autopsy

The Michelin ProTek Max tube I installed two years ago developed a slow leak this year, which I eventually ascribed to the valve stem, because the sealant should plug any other leak.

Cutting it open reveals the perfectly good greenish-yellow sealant:

Michelin ProTek tube - sealant

Michelin ProTek tube – sealant

The sealant also carries black rubbery grit / shavings / dust, perhaps intended to jam inside larger gashes while the sealant coagulates and binds it together.

There’s a lot of rubber floating around in there:

Michelin ProTek tube - rubber fragments

Michelin ProTek tube – rubber fragments

Dismantling the Presta valve stem show the rubbery crud on and around the valve seal and seat:

Michelin ProTek tube - fouled valve seal

Michelin ProTek tube – fouled valve seal

Whenever I pumped up the tires, I finger-tightened the nut to ensure a good seal, as you do with all Presta valves. Obviously, finger-tight can’t handle that much crud between the sealing surfaces.

I’m sorry to say I was right about the leaky valve stem, because I think all the ProTek tubes will fail in exactly the same way.

The valve has small wrench flats making it easy to remove, so I can at least attempt to de-gunk them when they develop slow leaks.

Color me unimpressed.



Vacuum Tube LEDs: 21HB5A on a Guilloche Platter

With the Joggy Thing running in LinuxCNC 2.7, touching XY off on the fixture was trivially easy:

LinuxCNC - Sherline Mill - Logitech Gamepad

LinuxCNC – Sherline Mill – Logitech Gamepad

The pips are 100 mm apart at (-50,-50) and (+50,50). Astonishingly, the laser aligner batteries are in fine shape.

I should have protected the platter before drilling all those holes:

Guilloche platter - drilling

Guilloche platter – drilling

All’s well that ends well:

21HB5A - Guilloche platter

21HB5A – Guilloche platter

It looks even better in the dark, although you’d never know it from this picture:

21HB5A - Guilloche platter - dark

21HB5A – Guilloche platter – dark

I wish I could engrave those patterns on already-drilled platters, but dragging a diamond point into a hole can’t possibly end well. I could deploy the Tiny Sandblaster with a vinyl mask, if I had enough artistic eptitude to lay out a good-looking mask.

, ,


LinuxCNC 2.7 vs. Logitech Joggy Thing

The old Atom running LinuxCNC for the Sherline finally stopped booting, so I popped the Optiplex 760 off the stack and did a live-USB trial run. The latency / jitter worked out around 25 µs, slightly worse than before, but still Good Enough, and the StepConf utility coerced the motors into working OK.

What didn’t work was the old Eagle-to-HAL code defining the Logitch Gamepad as a Joggy Thing to allow smooth joystick jog control. Well, stuff changes over the course of eight years, but, in this case, the fix turned out to be a one-liner: the probe_parport module isn’t needed nowadays.

With that out of the way, it runs fine:

LinuxCNC - Sherline Mill - Logitech Gamepad

LinuxCNC – Sherline Mill – Logitech Gamepad

The INI and HAL files defining the Sherline configuration as a GitHub Gist:

, ,

1 Comment

Kindle Fire Picture Frame: Side Block

A steel frame that Came With The House™ emerged from a hidden corner and, instants before tossing it in the recycle heap, I realized it had excellent upcycling potential:

Kindle Fire Picture Frame - Test Run

Kindle Fire Picture Frame – Test Run

Stipulated: I need better pictures for not-so-techie audiences.

Anyhow, my long-disused Kindle Fire fits perfectly into the welded-on clips, with just enough room for a right-angle USB cable, and Photo Frame Slideshow Premium does exactly what’s necessary to show pictures from internal storage with no network connection.

All I needed was a small block holding the Kindle against the far side of the frame:

Kindle Frame - side blocks

Kindle Frame – side blocks

A strip of double-stick carpet tape holds the block onto the frame. To extract the Kindle, should the need arise, slide it upward to clear the bottom clips, rotate it rearward, and out it comes.

Getting a good block required three tries, because the basement has cooled off enough to trigger Marlin’s Thermal Runaway protection for the M2’s platform heater. A test fit after the first failure showed the long leg was 1 mm too wide and, after the second failure, I reduced the fan threshold to 15 s and the minimum layer time to 5 s, producing the third block without incident.

The platform heater runs at 40 V and I considered bumping it to 43 V for a 15% power boost, but it has no trouble keeping up when the fan isn’t blowing chilly basement air across its surface.

The OpenSCAD source code, such as it is, doesn’t deserve its own GitHub Gist:

// Block to hold Kindle in a picture frame mount
// Ed Nisley - KE4ZNU
// November 2018

Protrusion = 0.1;

difference() {

    cube([18-4 + Protrusion,44-10 + Protrusion,10 + 2*Protrusion]);


, ,


HP 6201B Power Supply Meter Switch Rehabilitation

The meter range switch on Squidwrench’s HP 6201B bench power supply became erratic enough to get me to tear it apart:

HP 6201B Power Supply - meter switch nut

HP 6201B Power Supply – meter switch nut

For future reference, apply a 9/16 inch deep socket after loosening two teeny setscrews in the knob.

The date codes suggest a mid-70s assembly, but the design dates back to the 60s with no plug-in anything:

HP 6201B Power Supply - meter switch in panel

HP 6201B Power Supply – meter switch in panel

Rather than unsolder eight switch leads, I wrangled it into a visible location:

HP 6201B Power Supply - meter switch rear

HP 6201B Power Supply – meter switch rear

The knob and shaft sit on a separate metal bracket held in the white plastic ring with a pair of expanded prongs. Squashing the prongs together released the bracket, so I could see both sides of the switch wafer:

HP 6201B Power Supply - meter switch front

HP 6201B Power Supply – meter switch front

Note the copious markings which would, in the event of an actual finger fumble, give me a better chance of reassembling the spilled guts. Turned out not to be necessary, but it’s good to be prepared!

The actual repair consisted of easing a drop of DeoxIT Red into each side, spinning the central switch wafer / contacts a few dozen times, then reassembling in reverse order. Re-bending the prongs turned out to be the most difficult part, eventually requiring the designated Prydriver, and ended well enough.

A quick test with a 100 Ω power resistor shows the supply was working fine and the switch produced the expected results without glitches or twitches:

HP 6201B Power Supply - test load

HP 6201B Power Supply – test load

You just can’t beat the performance of old lab equipment!