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.
Mechanical widgetry
Having managed to mislay my dingy yellow kickstand plate, I made two more and this time hit ’em with fluorescent red paint. Ought to be unforgettable for another few years…
In theory, you’re supposed to apply a white undercoat. I hosed ’em down with many drippy, runny coats of red and it’s all good. This ain’t art and they get thrown on the ground, so what’s the point of being fancy?
The front of the label giveth (clicky for more dots):
The bottom line says “Ideal for changing oil and siphoning gas”, which is what you’d expect.
However, the back of the label taketh away:
If it manages to empty three small engine tanks and doesn’t immediately dissolve in gasoline, I’ll call it a win.
Sheesh and similar remarks.
The backside of the Lenovo N5901 Mini Wireless Keyboard (which arrived with the aforementioned Q150) has a black-on-black power switch with ON and OFF legends (yes, I think they’re backwards, too) embossed in the matte black case: under anything less intense than enhanced interrogation lighting, you (well, I) can’t determine the switch position.
Of course, the myriad certifications / ratings / labels required for compliance with all the regulations are perfectly legible:
Working a dab of white correction fluid into the letters makes them blindingly obvious; the smudges around the letters will wear off in short order.
I should probably add a bit of white to the switch background as well.
The SLA batteries in the MGE Ellipse 1200 UPS finally gave out. This picture shows how they’re arranged inside the box:
They’re 12 V 5 Ah batteries that are about 12 mm thinner than the garden variety 7 Ah batteries you can get everywhere; they’re not the same size as the generic 5 Ah batteries you might think would work. Of course, there’s not enough room inside the stylin’ case for the larger ones, either. I’m thinking of using fatter batteries anyway and putting a belly band around the gap. Maybe an external battery box with a chunky cable burrowing through a hole in the UPS case?
For what it’s worth, APC absorbed MGE a while ago (so the MGE website redirects to APC), got Borged by Schneider, then spat out MGE’s consumer grade UPS units to Eaton. You won’t find any of that documented anywhere, but here’s the response from APC after I didn’t find this UPS on their list:
I do apologize; when APC was acquired by Schneider Electric, the single phase UPS line that MGE once offered was sold to Eaton. Eaton now provides support for the MGE single-phase products. We do not sell batteries for these models. You will actually need to contact Eaton for further assistance regarding the MGE Ellipse units. You may click on the link below to go to Eaton’s website:
The Eaton website does have a battery replacement for this one, but sporting the dreaded “Contact us for price” notation. Given that I got the UPS cheap-after-rebate, I’m thinking maybe this isn’t worth the effort.
We divided an ancient Snake (a.k.a. Mother-In-Law’s Tongue) Plant and discovered the pot had no drainage hole, which is not to be tolerated.
It turns out that an ordinary carbide glass drill works just fine on glazed clay pots. Use a low RPM and very slow feed, flood the scene with water, and drill from the other side after the point breaks through.
The glaze inside the pot already had a flaw that let the water into the clay, from whence it seeped out through the unglazed lower rim. I suppose saturating the clay can’t possibly be good, but I’ve done this to many glazed pots over the years and none of them have ever complained, so it’s all good.
Some upcoming presentations on 3D printing need a way to show what’s going on inside the box. I’ve had various webcams affixed to various parts of the Thing-O-Matic, but nothing worked quite right: the camera was either in the wrong spot, at the wrong angle, or just flat-out in the way.
The helmet mirror project produced a trio of three-draw telescoping shafts that looked promising, so I drilled suitable holes in two chunks of scrap make-from plastic and produced a pole mount for a Logitech camera without doing a bit of machining. The camera wants to clamp onto a notebook and works fine atop a block of acrylic, with the cable secured to the base of the pole to prevent the whole thing from falling over at the slightest tug.
I briefly considered printing a nice clip to hold the cable to the pole, then came to my senses and used a cable tie. After all, that’s what they’re for, right?
A dot of clear epoxy in each hole prevents the blocks from rotating on the shafts; they’re sufficiently un-round to give it a decent grip. I clamped the pole in a V-block to keep it perpendicular to the base while the epoxy cured:
The white LEDs under the Z-stage produce far too much glare and reflect in the Kapton tape; a switch to knock ’em off for video viewing seems in order.
(If anybody else is keeping track, this is Post 1000. Although we humans love numbers with plenty of zeroes, Post 10000 will pose a challenge…)
After printing the Barbie Pistol, I discovered that moving the Z stage to anything less than the absolute maximum was a Bad Idea, so I changed end.gcode to simply home the Z axis to the top. That worked fine in RepG 24, but after printing a few things with RepG 25, I discovered that the Z axis now has uncommanded motion after that homing step: a G0 F4000 X0 causes the Z stage to drop by anywhere from a few millimeters to half the total travel.
Of course, the uncommanded Z motion depends on something imponderable, but it’s consistent for any given setup. This chunk of G-Code causes about 10 mm of downward Z motion:
G21 (set units to mm)
G90 (set positioning to absolute)
(- coarse home axes -)
G162 Z F1000 (home Z to get nozzle out of danger zone)
G161 Y F4000 (retract Y to get X out of front opening)
G161 X F4000 (now safe to home X)
M132 X Y Z A B (fetch home offsets from EEPROM)
G0 F4000 X0 Y0 Z30 (pause at center to build confidence)
(- draw square)
G0 F4000 X-45 Y-45 Z10 (to front left corner)
G1 Y45 F4000
G1 X45
G1 Y-45
G1 X-45 (return to front left)
(- move to eject position)
G162 Z F1500 (home Z to get nozzle away from object)
(G0 F4000 Z113) (this would work fine)
G0 F4000 X0 (center X axis)
G0 F4000 Y40 (move Y stage forward)
There’s a RepG ticket for that.
As nearly as I can tell, homing an axis trashes its coordinate value, so the only thing you can do next is set the axis coordinate value with G92 or M132. Given that those values are now stored in EEPROM, maybe it’s be a good idea to simply use them, without requiring another command after each homing command?
You’d want home offset values for both the maximum and minimum limits, to accommodate printers with limits on both ends of the axis, rather than the single offset now stored. The two homing commands (G161 and G162) could pick the appropriate offset, if a valid one was stored, and leave the coordinate unchanged (but not trashed!) otherwise.
There’s a RepG ticket for that.
The Smell of Molten Projects in the Morning 