randomdreams

home sewn mask with added shape-holding wire

We have some hand-sewn masks made of two layers of cotton. I modified two with the addition of wire in the top hem, allowing the wearer to bend the wire to fit the bridge of the wearer's nose. This significantly increases the mask's ability to seal to the wearer's face when inhaling, and may improve filtering when exhaling. (The positive pressure of exhaling tends to lift any mask that isn't held by adhesive or external force.)
Steel wire between 22 and 30 gauge, or copper wire between about 18 and 26 gauge should work for this. I used enameled copper magnet wire, 24 gauge, because that's what I have on hand. If you cut the wire at a sharp angle, you can preform holes in the fabric by separating it with a sewing pin, then gently press the wire through the preformed hole. I used the space between my fingernail and fingertip to back up the fabric, so the wire would protrude through, and then I could move along to the next one. I ran the wire back and forth, a running stitch, with about 6mm of space between each hole. It seems to work pretty well.

There is currently a lot of dispute about the effectiveness of DIY masks. I've found sources that say two layers of the sort of cotton used for t-shirts is about 50% as effective as an N95 mask, while one layer of tight weave quilter's cotton over one layer of flannel is somewhere near 80% as effective as an N95. https://www.npr.org/sections/goatsandsoda/2020/04/03/825639323/scientists-probe-how-coronavirus-might-travel-through-the-air has an extended discussion about current views on aerosol and droplet spread of viruses, which is poorly understood.

Crossposts: https://randomdreams.livejournal.com/974627.html

I feel like this is every year, but: today was bike-to-work day in the rest of the US, and was snow-like-crazy day here. This is why we have our bike-to-work day in mid-June.

Crossposts: https://randomdreams.livejournal.com/974454.html

My manager's been gone for three weeks and I've gotten a lot done at work and had a fairly fun time doing it, so that's nice.

The rice cooker blew out its own fuse again. This will be the third one I've replaced in this cooker, and the one before it also blew out two. I'm pretty confused by this. I've measured the wall voltage and it's approximately correct. It's possible the factory used a very marginal cheap fuse, but my replacement fuses were not cheap and (I calculated) are about 15% more than the surge current through the cooker.
At least I bought a lot of replacement fuses... Now I kind of wish I'd also bought a fuse socket and installed it.

Edit to add: rice cooker problem explained. I couldn't get an exact replacement so I got the type of fuse we use at work, without thinking too deeply about the use case. It turns out that the fuse being that close to the heating element means it needs to be a metallic case fuse with crimped connections. Soldered connections not only don't work, the solder has dissolved the adjacent wire.

Crossposts: https://randomdreams.livejournal.com/974245.html

Today's work project was a fun bit of learning. My coworker pulled a waveform off an oscilloscope. Not a picture of the screen, but the actual digitized data. Neither of us had any idea just how many points modern oscilloscopes can generate. He put the waveform in Excel, which promptly truncated it because Excel can only hold a million rows. So he showed up at my door.
I wrote something in C, and refamiliarized myself with malloc(). By some weird coincidence, what he wanted was half something I wrote yesterday (look for discontinuities) and half something I wrote a year ago (and stick them all in a specific dense format) so I managed to build him something pretty quickly, that with a bit of adjustment, could handle his four million line long text files and smash them down into 10,000 lines of relevant information. He was thrilled by it. (Now to see if I can somehow get that appreciation advertised upwards...)
I also thought of a possibly patentable idea. It's not a money maker, but it's the kind of thing my company would like to have locked up, so I'm going to try to find someone who appreciates weird ideas and see what it would take to have the company pursue this.

Crossposts: https://randomdreams.livejournal.com/974072.html

I ran a test for about six days straight, that generated 300MB of data or so, that I needed to filter down. My first filter, a simple delete-unnecessary-junk excel macro, pared that down to 50MB. But then I had a problem, that I'm still trying to handle.
I have four independent variables, that I'm sweeping through.
For each in (a-list):
For each in (b-list):
For each in (c-list):
For each in (d-list):
do stuff and measure stuff.

That's somewhere between 100K and 1M data points. I'm not really sure.
The issue is that at some point in each D sweep, an event happens, that results in a measurable outcome, and I have to figure out what everything else was, in the measurement before the event happened. This is complicated by sometimes happening before the first measurement (in which case there simply is no answer) and sometimes happening after the last event (again no answer) but once everything is in a giant excel spreadsheet, it's very difficult to tell a conditional formula or macro "hey only pay attention to events that happen within a d-sweep, not ones that happen at the boundaries between a, b, or c sweeps." Sometimes the event happens multiple times during the sweep, like it's in its no-event state, then in its event state, then back to no event, then back to event. All the things I've managed to write so far look at the overall pile of data, and trigger off every no-event-to-event transition, regardless of multiple events, of across-multiple-sweeps events, blah blah.
When I get done filtering I have a bunch of sparse columns: thirty or fifty blank rows followed by a row full of stuff. It took me a while to figure out how to condense that down. (In excel, the result of a formula is always some value, even if it's "" or #N/A or whatever: it may look empty but it is not empty, so I had to mess around a little to figure out how to choose all contents except for numbers and then delete those.)
Then I have this big mass of condensed, somewhat good data, only maybe 2000 lines of stuff or so, that I have to go through by hand and choose which ones to delete because they're clearly bad data, and then I have to go through that, and break it down by one of the sweep criteria and graph it.
There are so, so many places for mistakes of the copied-the-wrong-value sort here, and so many places where I have to make judgments about what constitutes good or bad data.
I'm trying to apply some basic statistics, stuff like throw away everything more than 3 sigma out, for instance. But I'm not sure that's valid. I'm not sure my assumptions about outliers are good, or about duplicates. My coworker, who might have better ideas, keeps looking at these giant masses of data, and saying "that's interesting" and getting off on tangents about how I'm measuring all these things and never answering my questions about data quality. My manager keeps sending me email asking me for finished analyses but never answers my questions about what constitutes good assumptions. (I've just started sending him my analyses with all the questions in there, so he has to read them to get to the conclusions.)

This is stuff I somewhat love. I suppose if I include all my questions and detail all my assumptions, that's the best I can do. It'd be nice to have more direction. But it's interesting learning a lot about data quality.

Crossposts: https://randomdreams.livejournal.com/973708.html

Every time it gets really windy (meaning once a week or so) the flapper on the oven hood vent starts clanging, as gusts of wind suck it open briefly and then it falls closed again.
Tonight while doing some other stuff I decided to fix it.
The problem with vent lines like this is that they're supposed to be airtight, so all the pieces fit together with positive overlap, meaning you can't just slide a piece out. It's held on both sides. So I had to drop the microwave from the cabinet it's screwed into, to get the space to get the flapper loose. Unfortunately, the hole in the cabinet the vent goes through interferes with the microwave being rotated down by the bracket against the wall, which I'd forgotten.
The process should go: lower microwave by about 2cm.
Pull upper vent hardware upwards, loosen the screw on the flapper, extract the flapper bracket.
It was a lot more difficult than that.
I wrapped some tape around the flapper itself, to dampen it, and

threemeninaboat found some adhesive foam and put a bit of that on, and I went to put everything back, and twisted and bent the side part of the vent system outwards so I could see in and make sure the flapper worked correctly.
It closed all right (my concern, as I'd bent the bracket it's in, during extraction) but I noticed it only opened halfway. Somehow, it hits against the inside of the upper vent section, which is an adapter that goes from a 2" x 6" rectangular opening to the 5" round vent line that goes up and out the side of the house.
Well, I can turn the flapper around so it swings the other way.
Except the bracket that holds it is a one-way bracket: it only bolts to the top of the microwave in one direction, because it has slide tabs to hold it down, on one end, and just a sheet of metal on the other end with a slotted hole to screw it down.
This is why I have calipers and a milling machine.
So now both ends have tabs and slotted holes, and the bracket is in reversed and I've verified that it fully opens (which makes the fan quieter) and closes.

This weekend involved an awful lot of house maintenance.

Crossposts: https://randomdreams.livejournal.com/973381.html

I went into work today to find out that my manager is taking three weeks off for family medical leave starting today. He didn't say anything about this to anyone yesterday.
I'm working on building a whole bunch of wrappers so software language A can call a big binary blob written in software language B. Last time I did this, it took me a week longer than I'd anticipated to get it working, for a large variety of reasons. (The API documentation was wrong, I didn't start asking for help or pointing out that I was going to have trouble meeting my deadline until I was right up against it, and the target hardware documentation was flat-out wrong about things like how to correctly power it.) So this time around I decided that I'd get it working before the "when are you going to have this done?" discussion even came up. I've figured out how to automate it, so I set that off and running and when it finished I emailed my manager that I had a good start on the software for our next project, that as of last Friday was my number one priority that nothing should distract me from.
He emailed me back almost immediately to ask me how an entirely different project, that was my highest priority last Wednesday, was going, and mentioned at the end of the email that he'd decided to cancel the project for which I was writing this software.
I turned to my coworker and said "hey, did you know your next hardware project has been cancelled?"
He sat there gaping like a fish for several seconds. I was all "I guess you didn't know either."

Crossposts: https://randomdreams.livejournal.com/973137.html

I'm reupholstering the Spitfire seats. When I took one apart, amidst the half-wastebasket-quantity pile of broken-down foam, I also found a business card for a place that repaired MG's. The telephone number on the card was a seven-digit number, which probably means it was 1970's. There was also a 1974 penny in the seat.
Getting the seat cover off was a pain. There's a big piece of foam glued to the seat's steel tubing structure. It has a horizontal slit in the middle of it. There is a flap on the vinyl cover that goes through that slit and then clips to the frame further down, to hold the concave surface of the seat back against the foam. The clips are very easy to put on but extremely difficult to remove: they're like binder clips with tiny teeth that grip the fabric, only they have no little wire loops to remove them. They simply press on, but there is no simple way to remove them.
Similarly, the recliner function of the seat is controlled via a lever, and removing it to get the seat covering off was really difficult. Good thing I bought a gear puller years ago.

Crossposts: https://randomdreams.livejournal.com/973021.html

I stayed home sick today because I felt awful, although I can't really say I was contagious or anything.
That gave me time to go to Boulder and get a key for

threemeninaboat's bike locker at the train station, the first locker reserved on the open-next-week line, and then physically verify the key's function, while also verifying that the lock does not in fact work on the door latch mechanism they've provided.
I also spent some time installing lock hardware on doors, because several of the doors have never had the right keys in the whole time we've lived here and when someone locks one of those doors it can be a serious hassle to get back through it.
This led to the discovery that there is no door sweep on the door between the garage and the house. There's a 10mm wide gap beneath it. That's about the same size gap between the garage door and the concrete.
No wonder we have a mouse problem.
I never thought to check, because the previous owners had carefully installed double-layer seals all the way around the door, as they did on every other one, to help prevent mice getting in.
It now has a nice custom-sawn piece of redwood that exactly fits in the space. Tomorrow that'll get bolted in place on the bottom of the door, when I have the energy to take the door off its hinges, and I'll put a commercial adjustable sweep behind it to air seal it as well as mouse sealing it.
As I was working on getting the parts together to fix this, I noticed the garage door opener no longer closes correctly.
This house needs some burnin' down.

Crossposts: https://randomdreams.livejournal.com/972700.html

Tonight's project. You know that thing in the bottom of a dishwasher that goes around and around? Well, mine now just goes up, once, and then doesn't do anything at all.
So I'm trying to figure out how to build a little retaining ring to reinforce the fingers were supposed to hold it in place but have now apparently worn out.

Crossposts: https://randomdreams.livejournal.com/972340.html

I've been annoyed at work, as usual. Right now it's because in the last ten days, I've had four separate "this is your highest priority: drop everything else including your last priority and focus on this and get me a presentation of your findings in two days" discussions with my manager, and none of the presentations has actually happened because of the next crisis. I've been spending a ton of time doing research and analysis to produce a big pile of well-ordered bits that are going to sit on a hard drive unused forever.
However, crisis #4 was interesting. There is an area of operation for our integrated circuit where it realizes it's about to get itself in trouble, so it reacts appropriately to avoid that happening. In doing so, it adjusts the frequency it operates, and because of some internal details, what it does is start clocking itself with two closely spaced pulses, then a pause out to what would have been its normal next pulse, then another two. It goes from tick tock tick tock to lubdub-lubdub-lubdub.
For some reason this totally freaks out one of the companies working with the chip. We've tried explaining this is expected functionality and they are having none of it.
Well, as it so happens, I'd run across this quite a while ago and thought it was weird, so I wrote some stuff to characterize it. Likewise, my coworker who handles system designs based on the chip thought it was weird, so he did a bit of work, and we talked about it and came up with some other things to check.
This directly contradicted my manager's instructions on what I was supposed to be doing, so I added it as an extension on some other testing, because I figured getting double the information for only about 10% more time spent could be worthwhile.
It was. When this issue reared its ugly head, my manager was all "do you have any information or data on this at all?" and I'm all "about 20 megabytes" and five minutes later had graphs and circles and arrows and all sorts of groovy stuff. So that was nice, and for once, actually got some attention.
Now I'm back to rerunning some of the test over a large area. I'm characterizing operation over a five-dimensional space, which is going to be fun to try to visualize.
The fun part of this was I got to load in a bunch of experimental software, piggybacked on the side of the (itself originally piggybacked) software I already had.

To geek out a bit: I've written something that assigns one execution thread to each interface, and on one, to each slow instrument running on that interface, so they're all operating in parallel, which massively reduces the test time, and massively increases the operation space I can reasonably expect to characterize. I have a primitive thread handler running, that figures out the thread execution speed and uses that to organize how the logfile is written, so that it starts writing the logfile before all the data is in but still manages to guarantee the order in which it is written. (This used to be critical. I just found a way to run my analysis software so it is no longer critical, but that's my next sneaky experiment.)

The system texted me a little while ago to tell me it hasn't blown up yet, which is nice, since it's running overnight. My coworkers were dumbfounded when I set them up with a snippet that emailed or texted them if a disaster happened: they had no idea that was possible. (And it's particularly nice because when I say "blown up" I mean enough fire we have to hit the emergency button to shut down all the power to the lab and then abandon it until the air system has cleaned it, but not enough to set off the sprinkler system.)

That was actually fun, particularly when the thread handler correctly started allocating resources to the different threads. I had no idea if that would work.

Crossposts: https://randomdreams.livejournal.com/972054.html

The sun visor on the driver's side of

threemeninaboat's car kept falling in her lap while she was driving. This is very distracting. I unbolted the bracket to find that it was broken internally. There is a long plastic cylinder into which the steel visor rod fits, and at the top end there are four little sprung teeth that engage a recess on the steel rod. Two of the teeth and half the cylinder were gone, broken off.
I made a spring by winding a piece of spring steel (a street sweeper blade I found in the gutter, as it happens) around a bolt to make an omega-shaped spring that fits around the remaining plastic and fits in the steel visor rod recess, so at least it's not falling in her lap anymore. I'll go over to the junkyard and get an actual replacement bracket at some point.

The window that got blown out in the Big Storm is finally done. I had to completely disassemble and rebuild the frame for it, as all the joints were shot and falling apart. I scraped all the glue out and reglued it, then redoweled the reinforcements, then bolted corner brackets on as well. The glazing strips were all trash so I cut some new ones out of redwood, which should resist rotting away from moisture, and used actual glazing compound to adhere the new glass into the frame. Apparently silicone is not long-term stable, while glazing compound is, so it's the right choice. Now the window can swing open so I can cool the place off in August when it's well above body temperature in there.

I thought I'd repaint the windowframe while I was doing this, and hey while I have the white exterior paint out, maybe I should touch up the rear porch fascia... and next thing I know, I ended up repainting around the garage, much of the carport, and most of the porch.

There weren't any corner brackets in my big bucket of rusty old brackets, so I ended up going to the hardware store for that. The Spitfire needs more exercise. The only available parking place was in front of the store on the right, which is about a 10% grade. This is interesting because the Spitfire's emergency brake doesn't work. It exists. You can pull it. The car slows slightly. The cables that pull on the rear drums, and the brackets they run through, are corroded enough that there is lots of friction. As a result, if the ebrake is adjusted tight enough that it works, it drags heavily when it's off. If it's adjusted so it doesn't drag, it doesn't apply enough force to stop the car, or keep it from drifting. So I put the car in first and got out. This means the only thing keeping it from rolling is the piston compression against the valves, and it's an old engine. Result is that about every five minutes one piston will leak enough to let the engine turn over to the next piston and the car will roll back just a little bit. That gets me motivation to shop fast. Ish two is that the Spitfire shipped new with grossly inadequate seatbelts and by the time I got it they were both inadequate and worn out. (Seatbelts in convertible have a lifetime and it's not long.) I replaced them with much better modern lap-and-shoulder belts, which is really nice, but non-modern-electric-intelligent-car retract seatbelts typically use a combination inertia reel and anti-rollover mechanism to hold the belt tight in the event of a crash. 10% grades are enough to activate the anti-rollover mechanism. (It's kinda cool: just a heavy ball bearing in a cup with a mechanism to detect when the ball bearing rolls up out of the cup past a certain amount.) So I couldn't pull my seatbelt out. Oh well. Roll back into the parking lot and get the seatbelt latched. I need to put airplane belts in that car.

Today was removing, cleaning, and reinstalling the drain in the bathroom sink, because it plugged up like it does every three months. The drainline to the main stack doesn't have enough slope to it. The fix is to tear out the bathroom wall and raise the line, but I tried that when I redid the kitchen. It's 3" copper pipe. Getting a three way joint in 3" pipe hot enough to shift the tubing is almost impossible. Maybe next time I'll insulate behind it with unitherm or something and use the glass torch.

I'm almost finished cleaning up all the mess from the flood when the window blew out in the middle of a blizzard. Almost.

Crossposts: https://randomdreams.livejournal.com/971791.html

I also saw a goose sitting on top of a gray toyota corolla, hissing at passers-by.

Crossposts: https://randomdreams.livejournal.com/971733.html

We went for a lunch bike ride. I got buzzed by a vulture because I was looking weak.
We stopped at a long stoplight where our road crosses a major four lane highway. Facing us across the road was a brown 90s hooptymobile and the driver was shrieking loudly enough to hear. I picked up the word “pedophile”. Light turned green and we started to cross. She pulled partway out into the intersection, stopped, put her cellphone out the window pointed at us and started screaming “there go the gay Nazi pedophile Zionists! I hope you are having a horrible day you dirty pedophiles!” as the cars vehind her began honking and swerving around her. So on some obscure Facebook conspiracy group there is a video of me smiling and waving as this woman screams abuse at us.
Which, let’s face it, beats being run over.

When I posted the above on Strava ("Grindr for bike racers!") my friend Bill, who I'm gonna name-drop because he either wins or takes second place in the US Nationals for his age group in road racing, crits, and team time trials every year for like the last 10 years, responded "maybe she thought you were a Merckxist!" which will be hilarious to about two people who aren't me.

My friend Tonya would accost people who took pictures of her and demand they destroy the pictures because she had extremely strong ideas about privacy, which I admire. I did not attempt to have anything like this conversation with Crazypants because there are few ideas worse than engaging with someone who is sitting in a two ton block of motorized steel when you're wearing about 28 grams of lycra and a pair of dirty shoes.

Crossposts: https://randomdreams.livejournal.com/971369.html

The window that got blown out of the workshop in the storm, is a wooden frame hinged at the top. The wood is old enough and has taken enough weather-based strife that when it's cleaned up with new glass in it it no longer fits in the window hole. So I need to redo the window panel and make it a little smaller, while still fitting the new sheet of glass.

The workshop's front door has a knob and a deadbolt. There has never been a key for the knob lock, and even if there was, it wouldn't work: someone tried to force it years ago and the key entry is too distorted for use. The problem with this is if someone turns the lock thumbturn, the door locks and I can't open it. (Which is why I added the deadbolt, for which I do have a key.)
This is only partly true. If the knob is locked, until yesterday I could push the door open enough to get the live bolt and latch to separate, because it's a double door and the other door is very poorly held in place.
This morning I added a fairly secure drawbolt and matching aluminum plates on the top and bottom of the secondary door, so now when they're latched, the door is secure against light attempts.
Which means I have to get the knob replaced with one that has a key, preferably a key that matches those in the house.
There are a ton of locksmiths willing to show up at my house and rekey locks, for $40 just to show up, and parts and labor on top of that.
But I did find an old-fashioned locksmith with a storefront who will take an old Schlage live bolt knob (or three: I might as well also get the ones in the garage-to-house door for which we've never had a key either) and redo the tumblers on all of them to match the house key.

This afternoon I spent a bunch of time showing

threemeninaboat's protege MiniMe (now rapidly becoming DeciMe as she grows) how to make chainmail. She was pretty good at it, although my giant old armor-quality rings were hard for her to close. I'll find a source for slightly more compliant rings next time around.

Crossposts: https://randomdreams.livejournal.com/971036.html

At midnight I turned on the bathroom sink to brush my teeth. This is the same sink that started leaking two weeks ago and I replaced the valves on both sides; ever since, its flow rate has been terrible, which I attributed to new, lower-flow valves. Well, it was particularly terrible. I think I've seen large dogs slobber at a higher flow rate than it was flowing. I'd turned on only the hot tap, and thought maybe if I turned on the cold tap it'd flow a bit more.
It didn't increase the flow volume at all.
A light bulb went on over my head: if 1+1 !> 1, it's not the valves that are the problem.
I pulled out my trusty leatherman do-everything multitool that

threemeninaboat gave me years ago, deployed the pliers configuration, and wrenched the aerator loose, unscrewed it, and took it all apart. It was completely jammed with slightly tacky black material, so I spent a while with a dental pick, poking it out of the screen and the diffuser. I'm pretty sure that's the remains of the insides of the o-rings that sealed the old valves.
Now the sink runs at a higher flow volume than the drain can handle, which is progress of some sort.

Crossposts: https://randomdreams.livejournal.com/970975.html

When I get home and sit on the couch, if I'm not petting Monty enough she jumps around until she has her front paws on the couch arm and her rear ones on the couch on the other side of me, so she can smash her barn door body sideways into my face while hitting me with her tail.
This is a great location for seeing that she has another big lump forming under one of her nipples, so it might be back to the vet for breast cancer round two.

I have this charming coworker, my closest friend at work, and happily we often get handed two halves of the same project so we work together a lot. He wants a particular area investigated, so I go design a bunch of tests and run them, and write up the results, and send them to him.
When I do this, I send him an excel spreadsheet, that is titled with what we've decided to call the test, and the tabs of the spreadsheet are labeled with what part of the test they contain, including one labelled "results and plots" that has only relevant information on it, graphically presented. In the email I mention the name of the test, what I tested, and where in the spreadsheet it's located.
I send him one of these pretty much every other day for a month and a half.
About once a week he's all "oh hey do you have any data on that one test we did last week?"
So I send him the same spreadsheet, with a paragraph in the email specifically pointing out where it is.
About twenty minutes later he'll stop by my office with his laptop and say "can we go over this, and you can show me where the data is and how to interpret it?"
So I think I am doing something drastically wrong in how I present data, but I'm not yet sure what it is. When I ask him he always says "oh, what you send is great: all the stuff I need is in there." But I'm pretty sure that's not right.

Crossposts: https://randomdreams.livejournal.com/970579.html

I found a glass place open on sunday. This alone is tricky, because when you search for 'glass shop' you get about 60% automotive glass/windshields, 30% hookahs and glass pipes, and the remainder are actual places that sell house windows. Anyway. This place was open on Sunday and had a bunch of positive reviews on Google. So I drove halfway out to the middle of nowhere to get some glass for my broken window... and the street address is a laundry. That's been there for years, obviously. So I called the phone number in the ad, and it rang, and rang, and rang, with no answer.
I've been hornswoggled, and the nice warm sunny day when I have time to repair windows is going to pass with no window repair.
Arrrrgh.

Crossposts: https://randomdreams.livejournal.com/970274.html

We had this blizzard on Wednesday, and I stayed home from work because it really was lousy weather. Somewhere in the middle, the wind was strong enough that it broke out a window in my workshop. (It was gusting to over 100mph, and because of snow and ice accumulation there were a lot of tree branches coming loose.) I managed to patch the window in the snowstorm, and today I went out trying to find new glass for it. The window is 40 inches wide, a single pane of glass, and all the glazier's putty and points were missing on one end (which is probably why it broke.) As I found today, it is surprisingly hard to find a place that is both open on the weekend and carries glass that wide. Everyone has 36" or meter wide. I found a place out in Commerce City that is open tomorrow, but my attempts today were futile, so the shop gets plywood fake window for another day.