Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Tag: Improvements
Making the world a better place, one piece at a time
Since the PiHole runs all the time, it now hosts an FTP server to stash snapshots from the cameras onto a 64 GB USB stick. I installed ProFTPD, which Just Worked with a few configuration tweaks:
UseIPv6 off
ServerName "PiHole"
DefaultRoot /mnt/cameras
RequireValidShell off
ftp_snapshot=true
ftp_host="192.168.1.2"
ftp_port=21
ftp_username=$(/bin/hostname)
ftp_password="make up your own"
ftp_stills_dir=$(/bin/hostname)
The last line uses a separate directory for each camera, although they quickly ran into the FAT32 limit of 64 K files per directory; reformatting the USB stick with an ext3 filesystem solved that problem.
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:
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 …
The Baofeng UV-5R radios on our bikes seem absurdly sensitive to intermodulation interference, particularly on rides across the Walkway Over the Hudson, which has a glorious view of the repeaters and paging transmitters atop Illinois Mountain:
Walkway Over The Hudson – Illinois Mountain Antennas
A better view of the assortment on the right:
Illinois Mountain – North Antennas
And on the left:
Illinois Mountain – South Antennas
Not shown: the Sheriff’s Office transmitter behind us on the left and the Vassar Brothers Hospital / MidHudson pagers on either side at eye level. There’s plenty of RFI boresighted on the Walkway.
Anyhow, none of the Baofeng squelch settings had any effect, which turned out to be a known problem. The default range VHF covered a whopping 6 dB and the UHF wasn’t much better at 18 dB, both at very low RF power levels.
We use the radios in simplex mode, generally within line of sight, so I changed the Service Settings to get really aggressive squelch:
Baofeng UV-5R – Improved Squelch Settings
I have no way to calibrate the new signal levels, but I’d previously cranked the squelch up to 9 (it doesn’t go any higher) and, left unchanged, the new level makes all the previous interference Go Away™. Another ride over the Walkway with the squelch set to 4 also passed in blissful silence.
If the BF-F9 levels mean anything on a UV-5R, that’s about -100 dBm, 20 dB over the previous -120 dBm at squelch = 9.
The new squelch levels may be too tight for any other use, which doesn’t matter for these radios. As of now, our rides are quiet.
[Update: Setting the squelch to 5 may be necessary for the Walkway, as we both heard a few squawks and bleeps while riding eastbound on a Monday afternoon. ]
I’ve finally had it beaten into my head: any public exhibition requires paper handouts, if only for younger folks who are too shy to ask questions. Paper may seem obsolete, but it serves as a physical reminder long after the sensory overload of a busy event fades away.
Hence, I made up cards describing my exhibits at the HV Open Mad Science Fair, each sporting a QR code aimed at far more background information than anybody should care about:
Because I planned to take my collection along to HV Open’s Mad Science Fair, I finally used a Round Tuit for some adhesive action.
The general plan was to punch a ring from double-sided tape, thusly:
Astable – Radome adhesive – poor surface
The OD required touching up the edge of a brass tube punch I’d made a while ago:
Astable – Radome adhesive – punch sharpening
It worked exactly as expected:
Astable – Radome adhesive – punching
Unfortunately, the 3D printed spider’s “spherical” socket has such a rough surface that the adhesive had too few contact points to hold the ball in place.
My fallback has become 3M outdoor-rated double-stick foam tape, so:
Astable – Radome adhesive – 3M foam tape
This leaves a small black ring visible between ball and socket. Recessing the foam tape by half its thickness should improve its ahem optics, although it’s probably not worth the effort with black PETG.
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.
The Smell of Molten Projects in the Morning 