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: Repairs

If it used to work, it can work again

Shopvac Model 500A Motor Wire Repair

The Shopvac Model 500A (1.25 HP!) inhaling dust from Tiny Bandsaw didn’t start up when I flipped the switch. It had been making horrible noises, but Shopvacs typically sound like they’re on the ragged edge of death, I wear 30 dB earmuffs when it’s running, and that wasn’t the problem anyway.

It turned out the hot (black) wire lead to the motor burned up:

Shopvac motor – charred wire

The neutral (white) wire over on the left side looked just fine:

Shopvac motor – good wire connector

But the hot wire connector was toasted:

Shopvac motor – charred connector

As the connector failed its resistance went up and so did the wire temperature, as shown by the plastic case:

Shopvac motor – melted cover

With barely an inch between the motor armature and the failed connector, this became a zero-Mulligan repair:

Shopvac motor – remaining armature wire

I clipped the failed connector off the wire, very carefully sanded off the burned insulation, then gingerly crimped the business end of a ferrule around the wire + a doubled length of 22 AWG hookup wire:

Shopvac motor – lengthened wire

Doubling the wire brought it up to 19 AWG, a bit larger than the 20 AWG armature wire, and maybe improved its durability. The ferrule surely isn’t rated for this sort of abuse, so I eased some solder into its end in the belief that any amount of solder is a better conductor than a similar amount of air.

Crimp the other end of the hookup wire into the business end of a solderless ring terminal along with the hot wire, anchor the ferrule to (and insulate it from) the armature with a wrap of silicone tape, do the same around the ring terminal, then squirt hot melt glue into the ruined connector housing to keep the wire from flopping around:

Shopvac motor – repaired wire

If it gets hot enough to melt the hot melt glue, there are other problems about to happen.

Reassemble in reverse order and the Shopvac once again makes its on-the-eve-of-destruction whine while inhaling chips.

A slip of tape marked “$5” fell off during this process, reminding me it was a garage sale find from quite a few years ago: saving it from an early grave may be an overall Good Deed.

2026-10-15
Window Latch Cam Rebuild

One of the living room window latches stopped working and, although the correct response would be to simply replace it, the window sash already had six holes surrounded by paint scars suggesting this wasn’t the first failure.

The latch as built:

Window latch cam – as built

The stamped steel spring holder was loose on the handle arm’s square pot-metal post, due to obviously poor factory swaging during assembly. Unseen below the plate is a cam molded into the handle intended to slide the white latch plate with the stamped post (over on the left) guiding the plate around the curved track and into the recess.

I don’t have a “before” picture of the cam, but it had completely worn away against the various steel parts. The task boiled down to replacing it with something more durable, which turned out to be a reshaped M3 brass screw:

Window latch cam – test fit

The Sherline setup to remove the worn cam, with the screw in place for a test fit:

Window latch cam – Sherline setup

The vise loosely clamps the handle, mostly for alignment, with the step block clamp holding it firmly in place.

The lever arm looked like this after poking the endmill into it a few times to clear the rubble, then using a smaller endmill as a drill to get a flat-bottomed recess:

Window latch cam – milled hole

Obviously, that was accomplished with eyeballometric alignment and manual jogging.

Reshaping and trimming the screw with Tiny Lathe produced a suitable cam-like object:

Window latch cam – screw installed

I planned to epoxy it in place, but AFAICT there is no way for it to go anywhere, so I just reassembled everything in reverse order:

Window latch cam – reassembled

I brutally swaged the square post with an automatic center punch cranked to maximum throttle while forcing the spring holder firmly atop the stack. The latch now moves smoothly and everything stays properly aligned.

While that was going on, the window sash had wood pins pounded into the errant screw holes with wood epoxy filling the gaps. Aligning the latch, drilling holes in the proper spots, and screwing the latch in place proceeded as expected.

That wasn’t easy, but now I can install plastic film over those windows for the winter.

2026-10-14
Samsung French Door Refrigerator Mullion Flipper

The vertical bar between the doors of the Samsung French Door refrigerator that Came With The House™ is called a “mullion” and the curvy doodad on top that moves it out of the way when you open the door is called a “mullion flipper”, which I learned while attempting to repair it:

Samsung Refrigerator Mullion Flipper – regluing

The entire top of the mullion broke off and, while a solvent bond can (ideally) be as strong as the original plastic, if the part broke once it will probably break again. Which happened in short order, despite all the clamping.

The official replaceable part is the entire mullion, but a more practical alternative is a cap fitting the top of the broken mullion, apparently either molded or 3D printed.

Having a 3D printer of my very own, a quick search brought forth a solid model of a mullion flipper that fit exactly:

Samsung Refrigerator Mullion Flipper – 3D print top view

It’s printed in clear PETG, which seemed a better match than white, and is held in place with a wrap of double-sided tape around the top, which may not be strictly necessary.

It flips the mullion just like the original:

Samsung Refrigerator Mullion Flipper – 3D print outside view

The yellow strip is 2 mil Kapton tape applied to both sides of the torn flexible seal running the length of the door, which we agreed was less awful than attempting to replace the entire seal on both doors. It must be trimmed slightly narrower than shown to avoid jamming on the other door.

Perusing previous posts will explain my overall low opinion of Samsung appliances.

2026-10-13
Countersunk Screw Recess Fillers

For reasons not relevant here, a friend must fill several pre-drilled countersunk flat-head screw holes with brass plugs suitable for M5 screws. These proof-of-concept samples give the general idea, with the red blotch on the left marking the first attempt:

Shelf flush screw fillers – samples

He gets to make as many as needed …

The flat-head screws have an 82° included angle, so the lathe compound angle must be 41°. Tiny Lathe lacks sufficient reach to accomplish that on the front side, but cutting the back of the brass rod with the spindle running in reverse will work:

Shelf flush screw fillers – lathe setup

The quick-change tool post is aligned parallel with the lathe bed to put the tools at the proper angle.

It turns out 41° is about as far as the compound will go:

Shelf flush screw fillers – compound angle setting

This, readers of long memory may recall, is the mini-lathe with the cross-slide DRO interfering with the compound enough to prevent it from cutting ordinary 60° screw threads, which is why the angle tops out at 42° instead of 60° in both directions.

The filler needs a 5.1 mm hole for EZ clearance, which is straightforward:

Shelf flush screw fillers – drilling

That was the first attempt after I got the compound angle worked out, which is why it eventually got the red mark. You want to drill on a flat end after countersinking with a center drill. It’s also good practice to drill only a few diameters deep, rather than trying to gun-drill sufficient hole for half a dozen fillers with one poke.

Run the spindle in reverse to cut the 41° angle on the back side:

Shelf flush screw fillers – backside cutting – detail

Run the spindle forward to separate the finished filler with a cutoff tool:

Shelf flush screw fillers – parting off

The length isn’t critical, so holding a millimeter scale against the right side of the tool and eyeballing the distance from the end of the taper should suffice.

Filing to polish, deburring to finger-frendliness, and similar activities are in the nature of fine tuning.

Now for some Quality Shop Time!

2026-10-09
Furnace Water Fill Valve Refurbishment

The water fill valve (a.k.a. water shutoff valve) for the gas furnace is inconveniently located behind the furnace and water heater:

Furnace fill valve location

After a few days of dripping Kroil penetrating oil on the valve body threads, the Greater Adjustable Wrench eased it just enough to convince me it would come apart, whereupon a search through the Big Box o’ Tubing disgorged a length of flexy silicone tube snugly fitting the valve drain port.

With the water turned off downstream of the house filter and the pipes depressurized, the tube directed most of the water into a bucket perched atop the furnace, with a scrap towel catching most of the remainder while unscrewing the valve. I clamped a rubber disk over the body while replacing the washer:

Furnace fill valve – ancient washer

Maybe that washer isn’t 60-some years old, but it’s definitely well beyond its Best Used By date. For the record, the fill valve uses the same 3/8L washer as the zone drain valves.

While I had it apart, I replaced the gasket, which was of course different from the drain valves:

Furnace fill valve – gasket

That was 25.4 mm OD, 22.7 ID, for a measured 1.3 mm width. The recess machined into the valve body limits the OD and the ID could go down to 22.0 mm. The gasket sheet is 0.8 mm thick, which seems to work well enough.

Reassemble in reverse order, wipe up various spills, turn the fill valve on to repressurize the furnace, close the valve, and the water pressure now remains at 12 psi as it should.

To the best of my knowledge & belief, every hot water baseboard furnace in all of our houses has operated with the water fill valve open: the pressure reducing valve sees normal water pressure upstream and regulates the boiler pressure, with a reverse flow check valve preventing backflow into the house plumbing as needed.

The Bell & Gossett instructions for the pressure reducing valve say, clearly and specifically, without asterisks or evasions, that you fill the furnace / boiler to the 12 psi regulated pressure, then close the fill valve. The furnace runs as a closed system, with the expansion tank keeping the pressure more-or-less constant at 12 psi.

It’s possible the pressure reducing valve is gradually failing, but it doesn’t matter with the water fill valve closed.

2026-10-08
HQ Sixteen: Grip Cap Assembly

After 3D printing another set of cap parts, glob the switches into place with tan JB Weld Plastic Bonder:

HQ Sixteen grip cap – switch gluing

More Plastic Bonder joins the cap body to the plug fitting into the handlebars:

HQ Sixteen grip cap – gluing fixture

I laser-cut an acrylic disk to fit the plug stem and hold the bottom of the plug flush with the bottom of the cap, with the PTFE fabric preventing inadvertent bonding of All The Things. It’s perched atop an empty thread cone to cure: quilting requires a lot of thread and I have a good stock of cones.

The button cap body solid model now includes alignment marks to eliminate the need for the bench block & clamps:

HQ Sixteen grip cap – alignment marks

Soldering the cable directly to the switch terminals is déclassé, but the collar prevents the cable from exerting any force on them:

HQ Sixteen grip cap – wiring

This time around, dabs of hot-melt glue hold the faceplate to the cap body.

I also used hot-melt glue to stick the transparent cover onto the handlebar body, as the OEM sticky tape was losing its mojo:

HQ Sixteen grip cap – wiring closeout

The rightmost three LEDs went dark a while ago and, while I had everything apart, I tracked the failure to the third LED from the right, replaced it, and it’s all good again. Those LEDs (plus the side groups) still can’t hold a candle to the Nose Ring Lights and Under-arm Lights, but it’s good to have all the lights working.

I managed to break one tiny wire on the header (wrapped in black silicone tape next to the IC on the right) joining the two cables from the control caps, but other than that things went smoothly.

Now I can start on other long-awaited tweaks before the next quilt arrives.

2026-09-29
HQ Sixteen: New Grip Control Cap Labels

The Run/Stop (⏯) button on the HQ Sixteen’s left-hand grip control cap recently became intermittent:

HQ Sixteen – grip cap installed – left

Which is a little more than a year after I built it, so I’m not red-hot pleased with the switch reliability. On the other paw, Mary has done a lot of quilting in the last year, generally controlling the machine with her left thumb, so that particular button has gotten a lot of use.

Because I glued the caps together, rather than trying to hide screws in finger-friendly locations, the replaceable unit is the whole cap.

I originally cut the cap labels using LightBurn’s Print-and-Cut tool to align the laser to the printed label, but subsequent experience making punched cards showed it’s generally easier (at least for my simple projects) to skootch the layout to match the laser position at known features:

HQ Sixteen control caps – laser alignment

Those small magnets hold the laminated label flat against the honeycomb.

The Position Laser tool puts the laser at a selected corner of the square, with Object Snap ensuring it’s really at the corner. Firing a test pulse to verify the red-dot pointer is aligned with the focused CO₂ laser spot is good practice.

Unlike the cards, the control caps don’t have fractional-millimeter tolerances, so, after verifying the printed label alignment at all four outer corners, it’s Close Enough™:

HQ Sixteen control caps – label cut

Cutting the adhesive sheet posed no alignment problems:

HQ Sixteen control caps – adhesive cut

Then it’s just a matter of peel-n-stick.

2026-09-28