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
The retina-burn orange ring is printed in PETG with my usual slicer settings: three perimeter threads, three top and bottom layers, and 15% 3D honeycomb infill. That combination is strong enough and stiff enough for essentially everything I do around here.
The insert on the left came out of its hole carrying its layer of epoxy: the epoxy-to-hole bond failed first. Despite that, punching it out required enough force to convince me it wasn’t going anywhere on its own.
The column of plastic around the insert standing up from the top fits into the central hole (hidden in the picture) in the bench block. Basically, the edge of the hole applied enough shear force to the plastic to break the infill before the epoxy tore free, with me applying enough grunt to the drill press quill handle to suggest I should get a real arbor press if I’m going to keep doing this.
The third insert maintained a similar grip, as seen from the left:
Brass Insert Retention test – C left
And the right:
Brass Insert Retention test – C right
The perimeter threads around the hole tore away from the infill, with the surface shearing as the plastic column punched through.
Bottom line: a dab of epoxy anchors an insert far better than the 3D printed structure around it can support!
Encouraged by the smooth running of the LM12UU drag knife mount, I chopped off another length of 12 mm shaft:
LM12UU Collet Pen Holder – sawing shaft
The MicroMark Cut-off saw was barely up to the task; I must do something about its craptastic “vise”. In any event, the wet rags kept the shaft plenty cool and the ShopVac hose directly behind the motor sucked away all of the flying grit.
The reason I used an abrasive wheel: the shaft is case-hardened and the outer millimeter or two is hard enough to repel a carbide cutter:
LM12UU Collet Pen Holder – drilling shaft
Fortunately, the middle remains soft enough to drill a hole for the collet pen holder, which I turned down to a uniform 8 mm (-ish) diameter:
LM12UU Collet Pen Holder – turning collet body
Slather JB Kwik epoxy along the threads, insert into the shaft, wipe off the excess, and it almost looks like a Real Product:
LM12UU Collet Pen Holder – finished body
The far end of the shaft recesses the collet a few millimeters to retain the spring around the pen body, which will also require a knurled ring around the outside so you (well, I) can tighten the collet around the pen tip.
Start the ring by center-drilling an absurdly long aluminum rod in the steady rest:
M12UU Collet Pen Holder – center drilling
Although it’s not obvious, I cleaned up the OD before applying the knurling tool:
LM12UU Collet Pen Holder – knurling
For some unknown reason, it seemed like a Good Idea to knurl without the steady rest, perhaps to avoid deepening the ring where the jaws slide, but Tiny Lathe™ definitely wasn’t up to the challenge. The knurling wheels aren’t quite concentric on their bores and their shafts have plenty of play, so I got to watch the big live center and tailstock wobbulate as the rod turned.
With the steady rest back in place, drill out the rod to match the shaft’s 12 mm OD:
LM12UU Collet Pen Holder – drilling shaft
All my “metric” drilling uses hard-inch drills approximating the metric dimensions, of course, because USA.
Clean up the ring face, file a chamfer on the edge, and part it off:
LM12UU Collet Pen Holder – parting ring
Turn some PVC pipe to a suitable length, slit one side so it can collapse to match the ring OD, wrap shimstock to protect those lovely knurls, and face off all the ugly:
LM12UU Collet Pen Holder – knurled ring facing
Tweak the drag knife’s solid model for a different spring from the collection and up the hole OD in the plate to clear the largest pen cartridge in the current collection:
Collet Holder – LM12UU – solid model
Convince all the parts to fly in formation, then measure the spring rate:
LM12UU Collet Pen Holder – spring rate test
Which works out to be 128 g + 54 g/mm:
LM12UU Collet Pen Holder – test plot – overview
I forgot the knurled ring must clear the screws and, ideally, the nyloc nuts. Which it does, after I carefully aligned each nut with a flat exactly tangent to the ring. Whew!
A closer look at the business end:
LM12UU Collet Pen Holder – test plot – detail
The shaft has 5 mm of travel, far more than enough for the MPCNC’s platform. Plotting at -1 mm applies 180 g of downforce; the test pattern shown above varies the depth from 0.0 mm in steps of -0.1 mm; anything beyond -0.2 mm gets plenty of ink.
Now I have a pen holder, a diamond scribe, and a drag knife with (almost) exactly the same “tool offset” from the alignment camera, thereby eliminating an opportunity to screw up.
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The yard camera now resides outdoors and plugs into one of three outlets on the patio, all of which have weatherproof covers attached by a bead chain to the trim plate:
Patio Outlet – new chain installed
That’s the after-repair condition, as two of the three chains were broken when we bought the house.
Stipulated: the covers needed scrubbing, but sometimes ya gotta stay focused on the Main Goal.
Two feet of 3.4 mm brass bead chain (because spares: ya gotta have stuff) arrived from eBay, I dismounted all three covers, and discovered the bell-shaped brass caps on the old chains were perfectly serviceable after six decades:
Patio Outlet – chain retainers
The outlets are wired to circuit breaker 28, of course.
Having enough chain to go around, each cover now sports a slightly longer leash than before:
Patio Outlet – chain assembly
Reinstall in reverse order, the camera rebooted as it should, and it’s all good out there:
As the basement’s fluorescent fixtures and lamps gradually die, I’ve been rewiring the fixtures for LED tubes, all bought from KEDSUM through Amazon. The first few batches looked like this:
Kedsum – good LED lamp
The most recent two batches seem cheapnified:
Kedsum – poor LED lamp
The tubes show similar changes, going from a stylin’ version to a simple cylindrical cap:
Kedsum vs Kedsun – tube end caps
The most recent carton label might lead you to think they’re counterfeits, but it could just be a simple typo:
Kedsum vs Kedsun – LED lamp carton
There’s absolutely no way to tell what you’re going to get from any vendor on Amazon (or anywhere else, for that matter), so there’s no point in returning them, but I’d hoped buying “the same thing” from “the same seller” would produce a consistent result.
On the other paw, the eyeballometric trend line since mid-April slopes at -1 lb/month and arrives at just over 150 lb in December, so progresscontinues apace.
Lacking any better method (“a tiny clip spreader tool”), I rammed the Jesus clip the length of the shank with a (loose-fitting) chuck in the tailstock:
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Start by prying the recessed top panel off the case:
Ooma Telo 2 – upper case latches
Remove the circuit board to expose the tiny speaker, taking care not to rip the tiny wires out of the tiny connector:
Ooma Telo 2 – OEM speaker to PCB
You can’t measure a dead speaker, but it seems to be an 8 Ω unit.
The speaker sits in a rubber surround, with a foam rubber cushion against the PCB, tucked into a walled garden stiffening the case:
Ooma Telo 2 – speaker port
I don’t happen to have a tiny 8 Ω speaker, but I do have a bunch of small speakers (Update: 28 mm OD), so I bulldozed those walls with a flush cutting pliers and a bit of cussing to make room:
Ooma Telo 2 – modified speaker port
Nibble an adapter ring to match the rim of the new speaker, thereby routing the sound out those little holes, and hot-melt glue it in place:
Ooma Telo 2 – speaker adapter
Hot-melt glue the new speaker in place atop the adapter, taking care to fill all the edges / cracks / crevices below it with an impenetrable wall of glop:
Ooma Telo 2 – replacement speaker installed
The sealing part turns out to be critical with these little speakers, because a leak from front to back will pretty much cancel all the sound from the cone.
Cut the wires off the old speaker, affix to the new one, replace the PCB, snap the case lid in place, and it sounds better than new.
Millions of transistors in those ICs, but Ooma can’t spec a good speaker? Maybe they should have used a bigger speaker to begin with; ya never know.
The Smell of Molten Projects in the Morning 