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Tonight I learned

that if you ask the debian installer to keep the data you have on a partition that you then want mounted, it will helpfully protect every gigabyte of it from the installation process by placing the files in the trash.

Oh, and that you can't use sudo to cd into a directory owned by root.

But I think the kid's box mostly works now. And he gets to sort the saved files.



Finally got one %#%# project to work, only a few months after it nominally went like. Replaced the solenoid in the remote-control door buzzer thingy with a servo, and now it all works. I am less and less patient with the analog world.

Above my pay grade

I have been doing so much stupid hardware hacking lately that I am starting to want to get back to writing. Too bad stupid hardware hacking is most of what I get paid to write about. But today was pretty maximally annoying.

It started out pretty well, finally hooking up the radio-controlled solenoid that lets people sit on their asses an press a keyfob instead of getting up to buss people in at the local co-working space. Then printing up the part that I plan to use for my light-switch servo thingy (after having coded up a single-use ATTiny85 servo controller last night and discovered that delayMicroseconds is off by a factor of 8). Then the guy who founded the space came by to play with the borked electronic lock, and we took apart the dead custom battery pack to find out that instead of something fancy it housed --

5 dead AAs.

If I had known this before the batteries died last month, I could have replaced them, saving the door from having to be jimmied. If I had known this even after the batteries died, I could have applied 7.5V to the external emergency power plug, ditto. Instead, I spent the rest of the morning taking apart much of the rest of the lock and determining that something is broken/jammed/whatever in the gear train where the little motor resides that retracts the bolt when you put in the right code. That's a part I couldn't promise to put back together again if I take it apart. So end of quest and probably major expense for nonprofit co-working space, all because of that one missing piece of information.

Then home, where it took way too long to reprogram the servo controller and solder it up. Then stupid stuff that is going to force me to code an SVG extractor because I don't run windows at home. Then disappointing snacks.

Tomorrow, one hopes, less of the same.


My cupcake CNC is getting to be like George Washington's hatchet. I replaced the old DC extruder motor with a stepper motor, then replaced the whole extruder with home built. Assembled the automated build platform, replaced the plastic assembly surface with steel, then cannibalised its parts for a plain heated platform with a copper surface. Installed a couple fans to cool the stepper and the driver boards. Threw in some LED lighting.

I still want to install end stops, maybe a geared extruder, maybe countersink the bolts on the build platform. Oh, and I've been upgrading the firmware. It runs much better under sailfish, what with smooth acceleration and not shaking the whole thing to bits. Or at least it did until I went from Build 973 to Build 1029 -- which also comes with a huge warning screen about not printing with a USB connection, unfortunately the only way I print.

Everything sucked. The extruder went completely wonky, the filament wouldn't stick to the build surface, prints that had been coming out fine were suddenly complete failures. So I downgraded the firmware, build by build back to what I had been using. Nothing. I downgraded the host software, replicator-g. Still crap. And all through this I knew the extruder was working, because I could spit out filament manually and it was fine. We're talking days here. Or nights rather, because I've got stuff to do during the day.


Then it struck me: what was that random jumper wire hanging out of a connector? It wasn't the led lighting, because that was OK. It wasn't the fan for the extruder stepper, because that went around back. Or the fan for cooling PLA because I took that off. It was the fan that cools the stepper driver for the extruder, which is cranked all the way up because it really doesn't have enough oomph to push the filament at full speed.

I touched the heat sink on top of the driver chip and burned the hell out of my finger. Aha. The driver chip has a thermal cutout to keep it from blowing up under excess load, and it was working just right . So when it got into a print, the chip would overheat and stop working, cool down a few hundred milliseconds later and start up again, overheat and stop, cool down and so forth. Resulting in some fraction of the intended filament coming out at unpredictable times. Or not.

I plugged the jumper back in, the fan stated whirring, then the jumper fell back out. So tonight I made a heavier gauge jumper. Printed something and it mostly worked. Hurrah.

But. The result of all this upgrading and downgrading and testing is that I really don't trust all the software any more. So I may upgrade very very slowly, or just leave things as they are, and walk very quietly when I'm anywhere near the cupcake. Whee.

Batman, The Musical

Let me unpack that. We sometimes sedate B in the afternoon by letting
him watch cartoons. Usually on our bed, where the TV on the wall is
connected to a Roku but not any broadcast source. So there is netflix.

And when B got tired of Pingu and Harold and Curious George there was
Spiderman. But not the original that we all watched, instead some
horribly animated 80s remix. B still looks at us funny when we hum the
old theme song.

And when he tired of Spiderman, there was Batman. The Brave and the
Bold, that is. It's 80s or 90s or something, and it's a crossover-fest
where all the played-out marvel/dc characters went to to retire, and I
hope that the writers were taking a lot of good drugs, because
otherwise they were really troubled people. The episodes are all aimed
at adults who are thoroughly familiar with Aquaman and the Flash and
that arrow guy and so forth but really don't like them much. (There's
even a cameo by grownup Robin, who wonders why Batman is poaching on
his turf.)

So that brings us to the musical episode. With the gorilla singing
bass. Duets. Dance numbers and a kick line. Villain backstory montage
and costume changes including pretty much every music genre from
classical through power pop by way of marching band. Scenery lifting
out of the way.

It is thoroughly freaky. And B has no idea. It's his favowite episode,
he says, but then he always says that. He has no cultural context to
understand just what a weird thing he is watching. And so I just watch
with him and wonder.


Adapting to the Digital Age

Here is (most of) the text of a notice sent to me by the Copyright Clearance Center:

New Grant Alert: $1,500 Conference Travel Grant


To view this email as a web page, go here [opaque url elided]

Copyright Clearence Center

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Two Lines in Bold Font

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lectus non ultrices accumsan, dolor diam venenatis lorem, eu mollis lorem
metus vitae nulla.

Subhead Goes Here in Bold font at 12pt
Nam rutrum magna in nisi dignissim et condimentum lorem blandit. Donec nibh
ipsum, dictum quis fringilla in, lacinia sed dolor. Cras ut viverra est.
Etiam aliquet convallis elit, commodo adipiscing sapien bibendum eu.

- Lorem ipsum dolor sit amet, co
- Yctetur adipie nisl nisi
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- Teros interdum a porttitor sapien ultrices. Fusce nis

Download Whitepaper


Sidebar Subhead
12pt Bold Font

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Sidebar Subhead
12pt Bold Font

Curabitur at mi et elit hendre rit ullamcorper. Mauris quis magna purus.
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This gives me so much confidence in their presentations.

Data is code.

Or is that data are code? I'm grumpy about this simple image-processing project I've been doing for so long because there are so many ^&#^%#$^ points in it. There are the corners for warping the image, a dozen different display blocks -- each a different size -- to have their numbers and letters recognized.

I've got to either measure those points by hand and type the results into my program, or else write yet more single-use ancillary bits to recognize those points and then dump them into a table. Either way is annoying. Part of me wants to write the ancillary bits because so much of the program is effectively embedded in those numbers, but part of me wants to be done with the damn thing already.

$59.99 saved is a penny earned

You know those projects that end up taking much more work than they should, and really ought never have needed doing in the first place?

Today I finally finished fixing the wind sensor on my cheapjack weather station. Winter before last the mounting pole fell down (note to self: wood shrinks, band clamps don't) and broke the sensor mounting plate, the tail of the wind-direction vane and all three arms of the anemometer. A few weeks ago, when the snow melted from where I wanted to put the thing, I went down to the basement with the bits and learned:

1. Parts not made of soluble plastic, so the plastic-welding cement had no effect whatsoever.
2. The solvent in my big bottle of superglue had evaporated, leaving a congealed mess that might hold if only it would set.
3. It wouldn't hold well enough to withstand brushing against my drill while I was trying to put it up.

4. The other big bottle of superglue, the "gap-filling" one, hadn't evaporated.
5. But that glue didn't stand up to vibration, say, a drill turning a mounting screw.
6. You can drill a tiny hole with the point of a file and insert a piece of wire to reinforce this stuff.

7. The sensor didn't work anyway, because
8. The internal batteries were dead and corroded (which I found out by disassembling the sealed part and finding them loose inside).
9. Just replacing them didn't help because
10a. You can't pull the circuit board out to replace the batteries without breaking a crucial part of the wind-direction sensor.
10b. Resetting the display to sync with the transmitter in the wind sensor is no help because (thanks, intertube forums) the wind sensor sends its data to the temperature/humidity sensor, which then passes the information (along with rain-gauge data) to the display.

Finally sorted all of that, and now I apparently have working sensors, although I'm not quite sure because the way you force the display to sync with the transmitter in the temperature/humidity sensor is by pushing one of the mode buttons until it beeps, and doing this also puts the display in some kind of weird cumulative-data mode that's too complicated to read.

Next step (because there is a PC dongle, but it doesn't talk to a Mac): OpenCV.

Sometimes it really is that easy

OK, so there's this shuttle box in the basement that I tried to build about three or four years ago and couldn't get to boot noway nohow or even show a splash screen, and then there's the other el cheapo refurb computer that just died one day. And there's its replacement, the $279 linux box from the place down the road. And there's J's G5 imac, which has been sitting in the basement waiting for recycling day for a few years, ever since it started booting with a tweed screen.

I've been taking the imac apart, mostly to procrastinate, partly because the motherboard (and yes it does have the dead bulging capacitors) has all those coils I want to steal for joule thief flashlights to give people, and because there might be some other useful stuff (anyone want in internal airport card or some 1-gig ram? or a big-ass lcd with a custom connector) inside it.

So one fine day -- I think it was while I had C in the basement gathering Raspberry Pi parts -- for no good reason I took the little 80gig boot disk out of the el cheapo and plugged it into the shuttle and turned the thing on, and damned if 5 minutes later when I turned around from doing a bunch of other things it didn't have a login screen. Now except for the x86 architecture these two machines have so absolutely nothing in common. Oh, and the screen was the wrong resolution and I had no idea what my password had been. (It took me three or four days to realize that "root shell" on the recovery-mode menu meant I had root and could add another user or just change my password; that's how stupid and rusty I am.)

Yesterday I asked J if it would be OK for me to cannibalize the hard disk from the imac, and she agreed. I plugged it into a couple of spare sata connectors, and not only did it appear as a disk, but HFS+ apparently opens just fine. So I have 4 gig of ram and 240 gig of disk and the machine mostly always turns on when I flip the power switch. Now all I need is to terminate another length of ethernet cable -- doesn't everyone have spares in their basement rafters -- and figure out a place to put the thing, probably behind the 3d printer. It would be nice to have something to talk to the printer and the other physical machines that isn't simultaneously doing slicing and renders and stuff like that.

Really, I'm just procrastinating, but I've built a couple of extruders and have plans for an hot end or two as soon as I find a random block of aluminum. And then maybe to get something actually printing.

And while I was rooting through the shuttle's BIOS setup I think I figured out why it wouldn't boot before -- the only option for booting from CD is with SATA, and the one I had installed was IDE. Whee.
This morning I took apart my mac mini (yep, with a putty knife) and swapped in 8 gig of RAM for the 4 that were in there. Wow. It's gone from "careful what you open" to "not a problem". I've got the Activity Monitor open, and free RAM appears to have stabilized at about 3 gig. Swap and pageouts are still firmly at 0.

I guess it was just a tipping-point thing -- if I still had 4 gig of RAM I'd be swapping every time I did anything (as I was). And modern bloatware does not swap prettily.

Makes me think that the next machine I get is really going to have way more RAM than I think I need.

And makes me cheerful that among all the messes and untimely death at least one thing is going right.



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