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.

Category: Home Ec

Things around the home & hearth

NuTone 8663RP Bathroom Vent Fan: Effective Repair
My high hopes for the UHMW bushing supporting the impeller lasted the better part of a day, because direct contact between the impeller and the motor bearing produced an absurdly loud and slowly pulsating rumble:

Bath Vent Fan – bushing installed

My hope that the UHMW would wear into a quieter configuration lasted a week …

Back in the Basement Shop, some free-air tinkering showed the impeller produced enough suction to pull itself downward along the shaft and jam itself firmly against the motor frame. My initial thought of putting a lock ring around the shaft to support the impeller turned out to be absolutely right.

So, make a small ring:

Bath Vent Fan – small lock ring – c-drill

With a 4-40 setscrew in its side, perched atop the impeller for scale:

Bath Vent Fan – small lock ring – size

It just barely fits between the impeller and the motor frame:

Bath Vent Fan – small lock ring – installed

This reduced the noise, but the hole in the impeller has worn enough to let it rotate on the shaft and the rumble continued unabated. The correct way to fix this evidently requires a mount clamped to both the shaft and the impeller.

Fast-forward a day …

A careful look at the impeller shows seven radial ribs, probably to reduce the likelihood of harmonic vibrations. After a bit of dithering, I decided not to worry about an off-balance layout, so the screws sit on a 9 mm radius at ±102.9° = 2 × 360°/7 from a screw directly across from the setscrew in another slice from the 1 inch aluminum rod:

Bath Vent Fan – mount ring – tapping

Centered on the disk and using LinuxCNC’s polar notation, the hole positions are:
```
G0 @9.0 ^-90
G0 @9.0 ^[-90+102.9]
G0 @9.0 ^[-90-102.9]
```
As usual, I jogged the drill downward while slobbering cutting fluid. I loves me some good manual CNC action.

Put the mount on a 1/4 inch tube, stick it into the impeller, and transfer-punch the screw holes:

Bath Vent Fan – mount ring – impeller marking

Apparently, some years ago I’d cut three screws to just about exactly the correct length:

Bath Vent Fan – mount ring – test fit – bottom

I knew I kept them around for some good reason!

The 9 mm radius just barely fits the screw heads between the ribs:

Bath Vent Fan – mount ring – test fit – top

Some Dremel cutoff wheel action extended the motor shaft flat to let the setscrew rest on the bottom end:

Bath Vent Fan – mount ring – shaft flat

Then it all fit together:

Bath Vent Fan – mount ring – installed

The fan now emits a constant whoosh, rather than a pulsating rumble, minus all the annoying overtones. It could be quieter, but it never was, so we can declare victory and move on.

Dropping fifty bucks on a replacement fan + impeller unit ~~would~~ might also solve the problem, but it just seems wrong to throw all that hardware in the trash.

And, despite making two passes at the problem before coming up with a workable solution, I think that’s the only way (for me, anyhow) to get from “not working” to “good as it ever was”, given that I didn’t quite understand the whole problem or believe the solution at the start.

But it should be painfully obvious why I don’t do Repair Cafe gigs …
2019-08-08
Monthly Science: Organ Pipe Mud Dauber Emergence

An industrious pair of Organ Pipe Mud Dauber Wasps assembled their nest last August:

Organ Pipe Mud Dauber Wasp Nest – side view

Their offspring began emerging in early July, with our first picture on 3 July. I’ll leave the image file dates in place so you can reach your own conclusions:

IMG_20190703_184657 – Organ Pipe Mud Dauber Nest – right

We think a titmouse (a known predator) pecked some holes, including the upper hole on the middle tube, as they seemed to expose solid (and presumably inedible) chitin from the outside:

IMG_20190703_184647 – Organ Pipe Mud Dauber Nest – left

More holes appeared in a few days:

IMG_20190709_172632 – Organ Pipe Mud Dauber Nest – right

The irregular spacing along each tube suggests they don’t emerge in the reverse order of installation:

IMG_20190709_172623 – Organ Pipe Mud Dauber Nest – left

Three days later:

IMG_20190712_181634 – Organ Pipe Mud Dauber Nest – right

IMG_20190712_181625 – Organ Pipe Mud Dauber Nest – left

Two weeks after the first holes appeared:

IMG_20190717_172908 – Organ Pipe Mud Dauber Nest – right

IMG_20190717_172922 – Organ Pipe Mud Dauber Nest – left

No more holes have appeared since then, so it seems one young wasp emerges every few days.

This nest produced about a dozen wasps, with perhaps as many launch failures. We’ll (try to) remove it and examine the contents in a few months.

We expect they’ll start building nests all over the house in another month …

Update: Fortunately for us, no nests appeared before the first freeze, so the wasps are holed up elsewhere for the winter.

2019-08-01
NuTone 8663RP Bathroom Vent Fan Bushing

The NuTone 8663RP (for future reference) vent fan in the Black Bathroom began making horrible grinding sounds and, after a day or two, stopped turning. Pulling it out showed the impeller had slipped downward on the motor shaft:

Bath Vent Fan – impeller shift

Which meant the impeller was now resting on the steel frame:

Bath Vent Fan – impeller interference

Curiously, there’s no retainer under the impeller preventing it from sliding downward, other than good intentions and a friction fit. Nothing lasts, although it’s been working for the last two decades, so I guess it doesn’t owe me much.

My first thought was to build a steel or aluminum collar with a setscrew to hold the thing up, but I decided to try a simple bushing made of UHMW polyethylene between the motor and the impeller.

Turning it to the proper length required a test fit, then another session on a mandrel made from some aluminum tubing:

Bath Vent Fan – bushing trim

The snout came out just long enough to clear the motor frame, resting the impeller’s weight atop the bearing around the shaft:

Bath Vent Fan – bushing installation

It’s hard to see between the impeller blades, but there’s actually a bit of clearance underneath:

Bath Vent Fan – bushing installed

Which left just barely enough room on the top for the retaining clip:

Bath Vent Fan – shaft clip – detail

I had high hopes for the UHMW, but it seems any contact between the rotating impeller and the stationary bearing transmits enough sound to be annoying.

So I must break down and build a collar, although it’s off the critical path right now.

As far as I can tell from the pictures, dropping $50 on a new fan unit will get me exactly the same problem. Whether it would last for two decades before failing is an open question, but my experience with freezer fans suggests what we have is as good as it gets and making a bushing is the least-awful way to proceed.

2019-07-31
Walmart Wiper Selector: FAIL

After five years, I figured it’d be a Good Idea™ to replace the Forester’s wiper blades. Being in the Walmart at the time, I tried to use their helpful Wiper Selector gadget:

Walmart Wiper Selector

You’d think whoever is responsible for updating / replacing such things would have done so several times during the last eight years.

2019-07-28
Shower Curtain Magnet Anchors

Back in the day, bathtubs had a porcelain coating over a cast-iron carcass, so embedding little magnets in shower curtains worked perfectly to keep the loose ends from billowing out of the tub. Surprisingly, even here in the future, with plastic bathtubs ruling the land, some shower curtains still have magnets. The mud-job tile walls of shower stall in the Black Bathroom have nary a trace of iron, but we though I could add ferrous targets for a new shower curtain, thusly:

Shower Curtain Anchor – installed

The magnet lives inside a heat-sealed disk, so it’s (more-or-less) isolated from the water. As you’d expect, it’s a cheap ceramic magnet, not a high-performance neodymium super magnet, with no more strength than absolutely necessary to work under the most ideal of conditions.

My anchors must also be waterproof, firmly attached, non-marking, easily removable, and no more ugly than absolutely necessary. The general idea is to slice the bottom from a pill bottle, entomb a thin steel disk in epoxy, and attach to the tile with a patch of outdoor-rated foam tape.

So, we begin …

Cutting a narrow ring from a pill bottle requires a collet around the whole circumference, which started life as some sort of stout aluminum pole:

Shower Curtain Anchor – cutting tube stock

Bore out the inside, with a small step to locate the bottle:

Shower Curtain Anchor – boring fixture

Clean up the outside, just for pretty:

Shower Curtain Anchor – turning fixture OD

Slit the fixture to let it collapse around the bottle, then chuck up the first victim with support from a conveniently sized drill chuck in the tailstock:

Shower Curtain Anchor – cutting bottle

I did a better job of cutting the second bottle to the proper length:

Shower Curtain Anchor – parting base

Nibble disks from sheet metal, half-fill the bottle bottoms with steel-filled (and, thus, magnetic!) JB Weld epoxy, insert disks, add sufficient epoxy to cover the evidence:

Shower Curtain Anchor – epoxy curing

Fast-forward to the next day, punch out two disks of double-sided foam tape:

Shower Curtain Anchor – adhesive foam

Affix, install, and it’s all good.

Actually, it’s not. The ceramic magnets are so weak they don’t hold the curtain nearly well enough to satisfy me. The next anchor iteration should have embedded neodymium magnets to attract the curtain’s crappy ceramic magnets, but this is Good Enough™ for now.

2019-07-26
Mower FOD

For reasons not relevant here, the lawn mower suffered some Foreign Object Damage:

Lawn Mower – bent blade mount

I’m sure the hard stop loosened the tolerances along the shaft, but the mower fired right up (with that new blade!) and has no more vibration than usual, despite the seriously bent blade mount.

I no longer have a deep emotional attachment to lawn mowers, which is apparently common, as the label advises me there’s no need to change the oil:

Mower Engine – never change the oil

Drive it ’til it drops …

2019-07-21
Houses Are Trouble: Electrical Service Division

The ancient utility pole on the north side of our property fell over a few hours after a thunderstorm rolled through:

Fallen Utility Pole – end view

Fortunately, the wire clamps were upward and it just lay there without sparks or excitement. It feeds the vacant house out back, so restoring power wasn’t urgent.

Unfortunately, the lines neatly bisected Mary’s garden:

Fallen Utility Pole – garden view

The utility crew arrived a few hours later, disconnected the triplex at the fallen pole, rolled it up, secured it to the source pole out front, and promised a different crew would replace the pole in a while:

Central Hudson truck – 2019-06-27

We agreed restoring service to other folks who needed it should take priority.

Mary’s been ducking the various cable TV / phone / FiOS cables ever since.

The pole has been God’s own toothpick for quite some time, as shown by this picture from 2001:

CHGE pole – rear – top

Fortunately for us, its pole tag hadn’t fallen off in all those years:

CHGE Pole Tag – mid-north

That little tag may save us ten large during this exquisite little inconvenience …

2019-07-20