Tuesday, February 20, 2024

gCode

GCode has a couple codes for cutting arcs and circles: G02 and G03.  I have spent a lot of time trying to figure out how to use it and I think I have figured it out. (No, I am still having trouble figuring this out.). In both cases, you specify the destination position and the radius of the circle.  (There is an i, j variant of this command which is supposed to be better at checking for consistent radius but I am hard pressed to see the advantage and the radius version is obvious.). G02 goes clockwise and G03 goes counterclockwise (or is it the other way around)?

Anyway, you are at xs, ys. You specify the destination xe, ye and a radius of the circle or arc.  It then cuts from xs, ys to xe, ye so as to describe a circle or arc around that radius.  The inner diameter will be r-mill diameter; the outer diameter will be r.  This matters if you want to cut a hole in the workpiece of size r-mill diameter or cut a circle r diameter.  If your destination is your current position, you get a circle.  

It seems to be a bit less exact than I expected.  I have been working in scrap acetal. 

G00 x.4375 y.4375 f5 (position at one side of the circle)

G03 x-.4375 y.4375 r .4375 f1 cuts an arc that it .8720" across.  I need to cut a hole .875" diameter in a piece of carbon fiber, so I will try this with r.4380 in a piece of acetal first and see what i get for diameter.


Things I Do Not Need But Always Wanted


Walther PPKS .22LR.

No, not because "Q" assigns it to James Bond (along with a S&W Featherweight .38) at the beginning of Dr. No), but because it is a very clever and timeless design.  A good engineering design will pull me under every time.  This is .22LR so not what you would carry in Khandahar, Oakland, or San Francisco, but a low recoil plinker that should build practice skills at a low cost.  (Not only the ammunition but the gun as well.  This is about half the cost of a PPKS in .380.)

Still: it is small enough to conceal very easily and light.  The Cramer Rule of Living Somewhere Uncivilized is that the mouse gun you have on you and with which you have gone through a couple boxes a month is a more effective defensive arm than the .45 ACP that you do not have on you because of its weight or bulk.

Ideally, you live somewhere that a handgun is not needed.  Since I moved to Boise, I have had few occasions where I felt a need to carry: at high density events which seems attract mass murderers is about it.  Of course, traveling to Connecticut a few years ago, I was glad that I was armed; their state capital city seemed remarkably dangerous.

Nice touch, the rear sight is adjustable for windage with included tool; they include several alternate front sights and tool for adjusting elevation.

I own an American Arms PK-22 which was a licensed copy of the PPK.  It does not lock open on empty magazine and uses a heel magazine release instead of the just below the slide push button release on this PPKS.  It is slightly smaller and only holds seven rounds.  It is also ugly and feels much less sophisticated.  It also cost me about $120 20 years ago.


Sunday, February 18, 2024

Sort Of A TEOTWAWKI Skill

The always interesting Cody's Lab presents Pop Can Thermite.

He starts with aluminum cans and sand.  He melts the cans to dispose of paint and other impurities, uses a lathe on the cast aluminum to make filings, then a ball mill to make powder.  

Electromagnet to extract magnetite from the sand.  Then he mixes it with the aluminum powder.  He does not reveal the ignition powder, but my guess is magnesium powder and either ammunition propellant or black powder.

Fire of great heat is produced.  During WW2, thermite bombs were the terror of London because you can only put them out with sand.  Water disassociates and burns.

The next and more intriguing step is to pour magnetite into cans, crush them, then use thermite to light them.  They burn just fine.

Thermite can be used for welding, burning through tank armor, cutting structural steel, I think, and producing a low grade of iron from a very common iron ore.  Add some coal to produce purer iron as a first step towards iron tools, spears, swords, etc  The scenarios under which these can be used in any post-apocalyptic novel are endless.

Of course, having a few pounds of aluminum powder already is obvious.

Why Are Students in Debt?

University of Pennsylvania president annual compensation above $22 million.  That is $60,000 per day.  If any corporate CEO was paid that well, the left would be screeching.

A Fearsome Future

Awesome documentary about the Gulags.  I suspect if Biden is re-elected, we will see this.

Why So Many Public Schools Fail to Teach Literacy to BiPOC Students

770 KTTH:

Students in a Seattle English class were told that their love of reading and writing is a characteristic of “white supremacy,” in the latest Seattle Public Schools high school controversy. The lesson plan has one local father speaking out, calling it “educational malpractice.”

As part of the Black Lives Matter at School Week, World Literature and Composition students at Lincoln High School were given a handout with definitions of the “9 characteristics of white supremacy,” according to the father of a student. Given the subject matter of the class, the father found it odd this particular lesson was brought up.

The Seattle high schoolers were told that “Worship of the Written Word” is white supremacy because it is “an erasure of the wide range of ways we communicate with each other.” By this definition, the very subject of World Literature and Composition is racist. It also chides the idea that we hyper-value written communication because it’s a form of “honoring only what is written and even then only what is written to a narrow standard, full of misinformation and lies.” The worksheet does not provide any context for what it actually means.

How could it, without engaging in the white supremacy of writing? 

Saturday, February 17, 2024

My Middle Name is Now "Ogg"

The latest genetic report from 23andMe says that I am less than 2.5% Neanderthal.  One of the traits associated with that ancestry sounds like a polite way of saying "hoarding.". This should not be any surprise.  Hunter-gathers can I'll afford to dispose of anything useful.