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

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
Furnace Zone Shutoff Valve

The upstairs baseboard heating loop collected enough air to frustrate the circulator pump, so I had to close the zone shutoff valve and open the drain valve to flush enough water through the plumbing to get the bubbles out:

Furnace zone drain and shutoff valves

Except: turning that little slotted stem required more torque than I was willing to apply. It may have last been turned a decade ago, during the final furnace servicing on record, but we’ll never know its story.

Furnace zone shutoff valve

Three days of dripping Kroil penetrating oil onto the shutoff valve stems and, just in case, their pipe threads, along with applying the maximum torque I was willing to apply, did the trick, albeit with a distressing amount of squeaking.

A hose from the drain valve to the sump pump pit took care of the outgoing water, flushing proceeded uneventfully, a test firing put hot water into the baseboard, and I could declare victory for the oncoming heating season.

For the record, this was an occasion justifying use of a slotted bit from my Brownell’s Magna-Tip Super Set:

Furnace zone shutoff valve – stem slot

It’s not a perfect fit, but much less sloppy than any other screwdriver in the shop: this is one valve I do not want to abuse.

2026-09-25
Printed Fragment Coaster: Delamination and Pinhole

Although “chipboard” is also known as “beer mat”, it’s not intended for long-term use under sweaty mugs. After a few weeks of daily use, this is obviously out of spec:

Printed Fragment Coaster – moisture damage

The aforementioned sweaty mug lifted part of a fragment off the coaster:

Printed Fragment Coaster – delamination

The chipboard is Quickboard from Makerstock, which is basically recycled-fiber chipboard with the advantage of being through-dyed in cheerful colors. It’s described as “2 mm-thick, three-layered board” and it looks like the core delaminated from the bottom layer.

Seeing as how it’s near the end of Sweaty Mug season, I smeared Elmer’s Glue Stick PVA adhesive over the fragment, stuck it back in place, and declared victory.

While doing that, however, I noticed a pinhole:

Printed Fragment Coaster – delamination detail

You may recall the outline came from hand-tracing a fragment of smashed glass in GIMP to get a path, then 3D printing a base to hold it:

Printed Coaster – Set C – oblique

Going back to the original GIMP tracing (storage being cheap, never delete anything), I missed a pixel:

Printed Fragment Set C – GIMP selection – errant pixel

Surely you can see it, particularly because you know exactly where it is. Right?

The (degenerate) path around that pixel becomes a tiny vector in LightBurn:

Printed Fragment Coaster – Set C – orphan vector

It’s easier to see there. Right?

Whereupon LightBurn dutifully punched a pinhole through the chipboard, because that’s what I asked it to do. It also punched that pinhole into the metallized paper reflector under the smashed glass fragment, but I didn’t notice it then, either.

Shrinking the GIMP selection by one pixel width, then growing it by one pixel would eliminate single-pixel selections: just another item on the to-do list while tracing fragments.

Ya learn something new every day around here …

2026-09-21
Another Snowflake Coaster Reaches EOL

Apparently a year in the bathroom under a cup with constant moisture is enough to ruin untreated wood inlaid in an acrylic coaster:

Mildew on wood snowflake coaster

A small 3D printed chipboard fragment coaster now enters service:

Printed Fragment Coaster – small

I recently ran into an interesting chipboard failure suggesting this one won’t last forever, so the clock is ticking.

About which, more later.

2026-09-18
Samsung Dishwasher Drying Cycle Crash: Wax Motor

Replacing the drying fan didn’t prevent the Samsung dishwasher from crashing when the drying cycle starts, so I eventually figured out how to run the “Smart Install” test sequence:

Samsung Dishwasher – DW80K7050US – p 37 – Service Test Mode

Which ticked through everything right up to the start of the “Check Drying” step:

Samsung Dishwasher – DW80K7050US – p 39 – Check Drying

Whereupon all the control panel LEDs went dark and a little red status LED on the PCB began blinking what must be an error code: long / pause / long-short-short. Of course, I cannot find any doc for that LED’s code.

The “Auto Door Open Actuator” is a wax motor, a device I had never encountered before. It opens the door through a whippletree pushing two tabs against the door:

Samsung dishwasher – door auto-open mechanism

The meter measures the voltage across the ~~wax motor~~ Auto Door Open Actuator through improvised widowmaker jumpers jammed onto the quick-disconnect fittings. As you might expect, the meter showed 000 VAC before, during, and after the crash, suggesting something is wrong with the relay intended to activate the motor.

Because the test sequence activates the drying fan after opening the door, the fan never even twitched.

For twelve bucks (spend up to $150 if you prefer), I had a generic DD66-00089A actuator in hand before dragging the dishwasher out of its lair and, being me, had to measure what it did:

Samsung Dishwasher – Door Actuator wax motor – test layout

It’s about 1.8 kΩ across the terminals and, not being fussy about its input voltage, will dissipate anywhere from 6 to 32 W in operation. Because the “motor” works by the force generated by expanding liquid wax, the response time obviously goes down as the voltage goes up.

After a few cycles to figure things out, plotting elapsed time against piston displacement is surprisingly linear right out to the 6.5-ish mm maximum stroke:

Wax Motor – time vs. displacement

It take much longer from a cold start, which is how it’s normally used, so the 30 s intercept at 0 mm is definitely on the low side.

Samsung no longer manufactures the DD82-01337A7050 control board, the usual aftermarket suppliers report it’s out of stock, and, given the lack of doc, I am loathe to pull it out of the dishwasher for failure analysis / repair. The one-hour cycle gets the dishes clean and a 46 minute countdown timer reminds me to open the door for drying, so the failure seems survivable for the immediate future.

2026-09-16