Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
The hidden part of all three LED arrays in the dead garage light looked like this:
LED Garage Light – inadequate heatsink compound
Although the compound was still gooey, there wasn’t nearly enough of it. The few tendrils on the heatsink suggest the LED array had bowed upward, pulled away from the cast aluminum, and eliminated any direct conduction.
A bit of probing showed each LED array had 16 series groups of 4 parallel LEDS, with one group in each array failed open. That group was toward the end away from the inadequate heatsink compound: the LEDs died from heatstroke brought on by neglect.
The Drawer o’ LED Arrays disgorged a bag of surplus LEDs labeled “10 W 9-12 V 750 mA”:
LED Garage Light – epoxy replacement
It’s sitting on a generous blob of steel-filled JB Kwik epoxy that should do a great job of conducting heat. A bag of cheap constant-current supplies is on order.
Amazon has similar “10 W 9-12 V 350-450 mA” arrays.
Try as I might, I can’t get 10 W from those numbers, but I’ve never understood advertising math.
A three-wing garage light Came With The House in the basement, where it served to light up the foot of the stairs. One of the 48 LEDs in one of the three LED panels began flickering brightly and, over the course of a few days, that panel went dark. The next time I turned on the basement lights, all three panels were dark.
Removing the screw-in lamp base:
LED Garage Light – overview
A closer look inside:
LED Garage Light – detail
The middle of the PCB is darker than the perimeter, with the darkest area around the black inductor standing up near the green filter cap. A blackened lump on the solder side that may have once been an SMD resistor evidently served as a fuse.
All three panels are in wired parallel, so the failed panel reduced the load on the supply, thus increasing the voltage on the remaining two panels enough to kill them off, too.
Worth noting: the black wire goes to the positive side of the LED panel. You can just see the + mark near the two connectors on the left side.
I wired each panel to a lashed-up bridge rectifier with a widowmaker extension cord from a variable transformer controlling the voltage, but none of them responded to the 150 VDC peaks: they’ve suffered Real Death.
The electronics landed in the recycling box and the three heatsinks are now in the Big Box o’ Heatsinkery, where they will surely come in handy for something.
The surprisingly readable 09/21 date code on the case says it’s just over four years old. Similar garage lights now run around ten bucks each and I wouldn’t expect them to last more than a couple of years.
A brace of cheap HD USB cameras may improve the scenery around here during video meetings. They were $16, marked down from an absurd $130:
HD USB Camera price history
Some poor schlubs certainly dropped more than twice the price of a Genuine Logitech camera on these critters, but a nearly total lack of demand must have had some effect.
They do take their stylin’ cues from Logitech, although the speckled pattern on a shiny plastic sheet is amusing:
HD USB Camera – styling vs Logitech C920
Unsurprisingly, the lens is fixed / manual focus. What looked like focus rings were in different positions on the two cameras:
HD USB Camera – lens focus notches
It turns out the rings were not glued in place, perhaps because they have absolutely no effect on the camera’s focus. Maybe there’s another camera model where they rotate the lens in a threaded socket, but this ain’t that.
The front panel has three pores:
A red Power LED is always on when it’s plugged in
A green On the air LED lights up when the camera is selected; I have no idea what the WiFi-ish glyph is supposed to represent
The “advanced noise canceling microphone” sits behind a pore offscreen left; the claim seems dubious.
Because these may go into smaller spaces, I dismantled the base to see what was involved. Most of the screws lie underneath thin foam sheets:
HD USB Camera – ball mount interior
The lower plate has a tripod mount and a folding bracket:
HD USB Camera – baseplate interior
The camera body has a ball mount with a few degrees of movment:
HD USB Camera – ball mount detail
Reassembled and stuck inside the laser cabinet with some good double-sided foam tape, it definitely produces a better image than the previous camera:
Platform camera view
Whatever noise cancellation the mic may provide is irrelevant in there: nobody’s listening.
Mary plugged a new ClimateLine heated hose into her Resmed Airsense 11 CPAP machine, spent the night feeling a bit chilly, and got an error message in the morning that boiled down to “Bad Hose”.
Unsurprisingly, the new hose looks just like the previous ones and the old picture remains relevant:
ResMed ClimateLine heated hose ends
The new hose has the same 12 kΩ resistance between the two outer contacts: the thermistor is fine.
The two inner contacts are an open circuit, not the expected 10 Ω: the heater element or (more likely) a connector joint failed. We don’t know if it was DOA or failed during the first use, but it does not respond to the usual wiggling and poking.
Her experience with Lincare’s Customer Disservice has been so terrible she refuses to start a warranty claim. She’ll continue using the old hose until it’s time for the next replacement and we’ll hope for the best.
As I understand the arrangement, she must get all the consumables (masks, hoses, filters, tanks) from Lincare for five years from the date of the original prescription. After that, she can order supplies from elsewhere, although that seller must have a new prescription.
Basically, Lincare gets five years of guaranteed business and, like the phone company of old, they don’t care about you because they don’t have to.
Always disable the rotary’s stepper driver before connecting or disconnecting its cable.
The Ortur YRC-1 rotary has a pulley ratio of 1:3, so the step/rev value is three times the DIP switch setting on the stepper driver. For this setup, 1600 → 4800 step/rev.
The honeycomb frame is a parallelogram, not a rectangle. I align the cardboard baffle / fixture to the bottom edge of the frame and the rotary to the bottom edge of the fixture opening, but your machine will be different. The angular alignment may not be off by enough to matter, but consistency is a virtue.
The Rotary.lbset and Linear.lbset files live on a file server with daily backups. Such backups will come in handy when you inadvertently overwrite one of those files with the other one. Trust me on this.
The Rotary.lbset file does not have Rotary Mode enabled, because the KT332N does not home the Y axis in that mode. If your rotary lacks a home switch, then it doesn’t matter and you’re on your own.
The KT332N controller has a [Reset] button that allegedly does a power-on reset and reloads all the changed Machine Settings. This sometimes does not work as expected: power-cycling the controller is the only way to be sure.
The autofocus operation must hit the focus pad, which can be ensured by positioning the pen near the pad, jogging the platform a few millimeters under the pen, tweaking X and the gantry while peering down parallel to the pen, then doing the autofocus.
The focus pad has a crosshair clearing the chonky Ortur 3-step jaws, but I set the controller’s [Origin] at the foot of the pad’s base for more elbow room.
The Z axis distance field in LightBurn’s Move window does not accept formulas, so you must divide the workpiece diameter by two. Using a focus stick to verify the ensuing nozzle-to-workpiece distance is a Good Idea™.
The LightBurn Job Origin dot must be on the top row, because the KT332N does not go into regions with negative coordinates. With the chuck on the left and the [Origin] just to its right, the upper left dot locks the LightBurn selection to the physical limits.
Selecting [Use Selection Origin] puts the Job Origin at the upper left (per the dot) of whatever you’ve selected, not everything on the LightBurn workspace. [User Origin] then locks the selection to the [Origin] set on the controller.
One of the inline switches I installed to replace the failed switches for the LED lights got unpleasantly warm enough to prompt an investigation:
Inline lamp switch – heat damage
Yeah, that is not a nominal outcome, particularly in light of the claimed “10 A 250 V” rating.
The overheated plastic pulled back enough to expose the terminal inside:
Inline lamp switch – visible terminal
There was a reason I’d wrapped those switches with known-good 3M electrical tape before deploying them.
That crimp connector took some heat and its screw looks even more unhappy:
Inline lamp switch – internal damage
It turned out the screw was an itsy too short to compress both the connector and the bent-metal conductor tab against the terminal block:
Inline lamp switch – misfit screw terminal
A 6 mm brass screw with a brass washer did a better job of compressing all parties into one conductive lump.
Although the switch now runs with the case at normal basement temperature, an allegedly UL listed replacement is on its way; it costs about five times more than that switch. If it behaves as it should, I’ll preemptively replace two other switches.
Two beads of hot melt glue hold the switch flush along the cover’s inside surface:
Ortur Chuck Rotary home switch – case exterior
One might argue for a tidy cover over those terminals.
While contemplating the layout by holding the switch here & there, seeing the switch roller neatly centered on the pulley hub told me the Lords of Cosmic Jest favored this plan:
Ortur Chuck Rotary home switch – case interior
A simple cam lifts the roller:
Ortur Chuck Rotary home switch – pulley cam
That’s obviously laser-cut acrylic sitting on double-sided tape.
Edit: The pulley ratio is 1:3, so the step/rev value is three times the DIP switch setting on the stepper driver.
Some finicky repositioning put the #1 chuck jaw on top after homing:
Ortur Chuck Rotary home switch – jaw position
A more permanent adhesive under the cam may be in order.
Wiring the normally open switch contacts in parallel with the existing Y axis home switch lets both the gantry and the rotary trigger the controller. The front-panel switch ensures only one of those two can move:
Laser Rotary – control switch
With all that in place and the switch flipped, the chuck rotates happily and homes properly with the controller in normal linear mode.
Spoiler: A Ruida-ish KT332N controller ignores the Y-axis Home enable setting with Rotary mode enabled, because everybody knows a rotary has no need for a home switch.
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The Smell of Molten Projects in the Morning 