Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Based on the results from last time, I set the temperature to the cooktop’s maximum 460 °F and, bother fiddling with condensing the moisture on a lid, and let it cook.
Weighing the beads (about) once an hour:
Start: 700 g
1 hr: 678 g
2 hr: 666 g
3 hr: 661 g
The 39 g water loss is 5.6% of the wet weight and 5.9% of the dry weight, which is roughly the amount absorbed by both silica gel and alumina after a month or so in the filament boxes.
During those hours the surface temperature rose from 73 F to 190 °F, although the exact number depends on exactly where the IR thermometer was staring. Stirring the beads to get an average temperature might be more convincing, but not by much.
Exactly how dry the beads become after three hours remains unknown, but the temperature increase suggests most of the water has gone elsewhere.
Cooling the beads in a covered bowl and pouring them into a jug produced a total weight of 767 g, which settled at 770 g over the course of two days; the jug seems reasonably vapor-tight.
Alumina beads seem much less prone to damage by overheating than silica gel beads and have similar performance in the boxes, which makes them a strong contender for the next round.
The last three boxes had 50 g of activated alumina and got fresh doses from the same bottle.
The other boxes had 50 g from the original bottle of silica gel beads and now have regenerated (and likely damaged) silica gel beads.
AFAICT, the meter in the orange PETG PolyDryer box isn’t working right, because the humidity indicator card in there has blue spots all the way down to 10%, just like the other boxes. Color differences for meter readings in the teens may be too subtle for my eyes.
Mary made a frame weight to maintain tension on the fabric in the HQ Sixteen longarm:
Longarm fabric frame weight
It’s a sturdy cloth tube filled with BBs, somewhat like a grossly overweight door snake (a.k.a. draft stopper).
The bottle of 6000 copper-plated steel BBs arrived in an overwrap bag of the sort Amazon applies to all bottled products. This was a Good Thing, because the scrap of packing paper did nothing to cushion the bottle in an otherwise empty box. The bag contained most of the shattered cap and a few BBs, with escapees rattling around inside the box and surely a few left along the way.
So I conjured a replacement cap from TPU:
Crosman BB bottle cap – solid model – build view
It fits around the bottle neck and snaps onto the spout just like the original:
Crosman BB bottle cap
Except this one is unbreakable.
The strapless TPU cap was a quick test to verify the fiddly shoulder snapping onto the bottle snout:
Crosman BB bottle cap – solid model – section view
As it turned out, we poured all 6000 BBs (minus those few lost-in-transit strays) into the cloth tube, but the bottle will come in handy for something someday.
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The rods (a.k.a. tubes or poles) holding & guiding the quilt top / batting / backing fabric on Mary’s HQ Sixteen longarm quilting machine span the eleven feet of the table:
HQ Sixteen – table overview
The two end plates are 1/4 inch steel plate with four punched holes for the rods / tubes, which look remarkably like EMT. The machine is two decades old and Mary is (at least) the third owner, so it’s no surprise the rods long ago wore through the white powder-coat paint on the plates and, during the course of a long quilting project, now deposit black dust on the table.
Black dust not being tolerable near a quilt-in-progress, Mary asked for an improvement.
The tube OD is 28.7 mm (so it’s probably 1 inch EMT) and the plate hole ID is 31.2 mm (likely a scant 1-¼ inch punch), leaving barely a millimeter of clearance all around. I wanted to make a bearing from suitably slippery Delrin / acetal, but figured 3D printed PETG would suffice for at least while.
The proper term is “bushing“, because it has no moving parts:
Rod Bearing Sleeve – solid model – show view
On the right side, the bushing rim must fit between the sprockets and the plate:
HQ Sixteen rod – right front
The spring-loaded pin holding the tube in place (visible on the inside bottom) sets the maximum length:
HQ Sixteen rod – right outer
The left side has none of that, so I made the bushings a little longer:
HQ Sixteen rod – left inner
The left-side bushings will need a better design should normal back-and-forth sliding push them out of place.
A touch of silicone grease around the plate holes makes those bushings / bearings turn sooo smooth.
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The business end of a cheap stick blender we bought a year ago to replace the previous stick blender (*):
Fresko stick blender
This one failed just slightly beyond the duration of its one-year warranty, apparently with one of the shaft bearings seized to the extent of making the blade un-turnable even by (carefully protected) finger force.
With nothing to lose (and a new blender inbound), it stood in the Basement Shop in that orientation for a week while I dripped penetrating oil around the shaft and wiggled the blade slightly back-and-forth. The bearing eventually broke free and the blade turned reluctantly.
Still having nothing to lose, I gave the shaft a few shots with a drift punch, moving it a few millimeters in each direction. This apparently disturbed the seized bearing just enough to let it turn less reluctantly, with more penetrating oil improving the situation.
Mixing a jar of water went well, even on high speed, but I doubt the bearing is in good health. We decided a blender with penetrating oil tucked up inside should be disqualified for food processing.
When it first locked up, I bought a significantly more expensive stick blender, knowing full well more money does not imply better design / better materials / more QC. This one is now designated as a Cold Backup blender for garden & shop use.
(*) For the record, my 3D printed shaft adapter failed while converting garden tomatoes into thick & zesty pizza sauce. I’m unsurprised PETG-CF wasn’t up to the task.
For obvious reasons, it doesn’t fit with the inlet scoop I installed as part of blinging the MK4:
Prusa MK4 Nextruder Tool – inlet scoop installed
Removing the scoop is a matter of removing those two cap screws, which is no big deal, but a little flush-cutter action made that problem Go Away forever:
Prusa MK4 Nextruder Tool – inlet scoop mod
Yeah, I should have modified the solid model. Maybe next time.
A version of the tool fits extruders covered with an Official Prusa Silicone Sock thermal insulator, but they were out of stock when I was in the mood. My heater wears a knockoff sock:
Prusa MK4 Nextruder Tool – silicone sock vs nozzle
Unlike the Official Sock, there’s no way to get a wrench on the nozzle with that one installed, but removing the sock is no big deal.
I apparently installed the nozzle / heater block slightly higher than specified, so the tool didn’t quite fit. Loosening those two thumbscrews and lowering the nozzle to fit the tool solved that problem. Fortunately, the automatic bed leveling routine corrects for nozzle height differences on the fly.
The scoop is back on the fan, the sock once again surrounds the heater, and I can easily swap in the 0.8 mm nozzle when the time comes.
The Smell of Molten Projects in the Morning 