Monday, January 31, 2011
Jack Goes To Egypt
I was talking to my friend Jack at lunch today about Mubarak and Egypt, and this little bit of information fell out.
Jack visited Egypt back in 1997, fourteen years ago. His visit was just about a month after some terrorists shot up a bus load of tourists and about a month before another bunch of terrorists shot some tourists at one of the ancient temples.
He was with a group, and the group had a couple of private security guys with them at all times. They were dressed in plain clothes, not uniforms, and carried guns (with bullets).
There were military guards with guns at most tourist locations, though it wasn't always clear whether they had any bullets. He saw one guard with what appeared to be a stainless steel AK-47, but when he got a little closer he saw that it wasn't stainless, it was a regular blued steel gun that been worn and/or polished so much that all of the bluing had been worn off.
Sunday, January 30, 2011
Tess of the D'Urbervilles
A scene from the movie Tess of the D'Urbervilles popped into my mind the other day. I don't know why, it's been a long time since I've seen the movie, but this one scene, only a few seconds long, has stayed with me.
It is the scene with the threshing machine. Tess is working away, feeding wheat to the machine and it is getting dark. She has a small kerosene lantern sitting nearby, and I am thinking this is a disaster waiting to happen. A container of flammable fuel, a flame, and more straw than you can shake a stick at. All we need is one careless moment and the whole thing is going to go up in flames. If you saw the movie you may remember it as a series of small scale disasters. One thing after another goes wrong, so I was fully expecting the lamp to get knocked over and set the whole place ablaze. I was relieved when that didn't happen.
This was, of course, typical of the way things were done in the days before OSHA. Dangers were everywhere and you had to careful if you wanted to go home at the end of the day. So kudos to the movie makers for this bit of authenticity.
It is the scene with the threshing machine. Tess is working away, feeding wheat to the machine and it is getting dark. She has a small kerosene lantern sitting nearby, and I am thinking this is a disaster waiting to happen. A container of flammable fuel, a flame, and more straw than you can shake a stick at. All we need is one careless moment and the whole thing is going to go up in flames. If you saw the movie you may remember it as a series of small scale disasters. One thing after another goes wrong, so I was fully expecting the lamp to get knocked over and set the whole place ablaze. I was relieved when that didn't happen.
This was, of course, typical of the way things were done in the days before OSHA. Dangers were everywhere and you had to careful if you wanted to go home at the end of the day. So kudos to the movie makers for this bit of authenticity.
Saturday, January 29, 2011
Gun Mechanics
Guns, mechanically speaking, were always kind of an alien species to me. Unlike cars, there are not very many parts, the parts seldom wear out, and I don't think I've ever seen a hexagonal nut used in one.
Then there are the parts themselves. Very complicated shapes, very difficult to machine. Parts for automobile engines are simplicity itself, relatively speaking. Clamp the engine block in a milling machine, bore the cylinders, mill the top surface flat, drill and tap the holes for the head bolts: boom, boom, boom.
Or maybe I just never spent any time studying the intricacies of gun machining. If I look closely, I can see how it could be done, but geez, what a lot of tedious, small, detailed steps. Clamp it like this, use this kind of a tool, cut a groove from here to here (and no further!), at just this depth, just this width, and just this position. Now repeat for the 37 other little grooves and notches. OK, now you are done with the first part and you can go on to the dozen or so other, equally complicated parts that go into a gun.
Then there's the little parts. This one has always been a bit of stinker. How do you clamp something that small and delicate hard enough that you can mill it? Sometimes I think the answer is to mill it out of the edge of a larger piece, and then cut it off. It has to be right, because once you've cut it off, you are done with machining. You might be able to file it a bit, but that is only good for a few thousandths of an inch.
Lastly, there's the barrel. Pistol barrels aren't too bad, they are only a few inches long, but rifle barrels, they are measured in feet. How do you drill a straight hole through two feet of solid steel? One might think it is a straight forward proposition: clamp the barrel in a big drill press, put a long bit in the chuck and drill away. In a perfect world, with perfect steel and a perfect drill bit, that might work, but we all know this isn't a perfect world. Even a very good grade of steel can have minor inconsistencies. Drill bits these days are indistinguishable from perfect. The drill bit is going to wander. You start at the center of one end of the barrel and by the time it gets to the other end it could be coming out near the edge.
Someone must have figured out the trick, because the world has made millions of rifles. This has been bugging me for years. I looked for this information a while back (a few years?), but found nothing. This time I got some answers. Is it because the internet is expanding? Or it because this time I was holding my mouth right (and the search phrase I used happened to work)?
Wikipedia has a short explanation, Lilja Precision Rifle Barrels has a longer one, but the authority is the Machinery's Reference Series #25 published in 1910. In other words, somebody figured out how to drill gun barrels a hundred years ago.
Gun design is a whole other issue. The basic requirements are pretty straight forward: barrel, breech block and locking mechanism, but the details of how they are implemented are sometimes a mystery.
Take any gun apart and you can see how it works, but start examining how all the pieces fit together and trying to figure out what function each little groove and notch serves can be baffling. Sometimes there does not appear to be any point at all. Sometimes the mechanism appears to overly complicated for the apparently simple task it is meant to serve. I suspect that sometimes it is, but it might just as well be a case of "this complicated design" functions reliably, where the simpler design we used earlier did not, and that is something you only find out when you are around for the failures.
Guns are really pretty amazing devices. The basics were pretty much all figured out a hundred years ago (insert mention of the Holy Prophet of Gun Design: John Moses Browning and his self-adopted granddaughter, Tam*). The .45 caliber and 9mm handgun and the 30-06 and 50 caliber BMG all came into existence about then, and are still with us today. Everything that has been done in gun design since then has been minor variations, subtle refinements and experimentation.
Smokeless powder is what gave rise to modern firearms. It produces pressures never before encountered and so opened up a whole new area of technical challenges, which gave rise to some bizarre details found in gun designs.
* thanks to Roberta X for that phrase.
Then there are the parts themselves. Very complicated shapes, very difficult to machine. Parts for automobile engines are simplicity itself, relatively speaking. Clamp the engine block in a milling machine, bore the cylinders, mill the top surface flat, drill and tap the holes for the head bolts: boom, boom, boom.
Or maybe I just never spent any time studying the intricacies of gun machining. If I look closely, I can see how it could be done, but geez, what a lot of tedious, small, detailed steps. Clamp it like this, use this kind of a tool, cut a groove from here to here (and no further!), at just this depth, just this width, and just this position. Now repeat for the 37 other little grooves and notches. OK, now you are done with the first part and you can go on to the dozen or so other, equally complicated parts that go into a gun.
Then there's the little parts. This one has always been a bit of stinker. How do you clamp something that small and delicate hard enough that you can mill it? Sometimes I think the answer is to mill it out of the edge of a larger piece, and then cut it off. It has to be right, because once you've cut it off, you are done with machining. You might be able to file it a bit, but that is only good for a few thousandths of an inch.
Lastly, there's the barrel. Pistol barrels aren't too bad, they are only a few inches long, but rifle barrels, they are measured in feet. How do you drill a straight hole through two feet of solid steel? One might think it is a straight forward proposition: clamp the barrel in a big drill press, put a long bit in the chuck and drill away. In a perfect world, with perfect steel and a perfect drill bit, that might work, but we all know this isn't a perfect world. Even a very good grade of steel can have minor inconsistencies. Drill bits these days are indistinguishable from perfect. The drill bit is going to wander. You start at the center of one end of the barrel and by the time it gets to the other end it could be coming out near the edge.
Someone must have figured out the trick, because the world has made millions of rifles. This has been bugging me for years. I looked for this information a while back (a few years?), but found nothing. This time I got some answers. Is it because the internet is expanding? Or it because this time I was holding my mouth right (and the search phrase I used happened to work)?
Wikipedia has a short explanation, Lilja Precision Rifle Barrels has a longer one, but the authority is the Machinery's Reference Series #25 published in 1910. In other words, somebody figured out how to drill gun barrels a hundred years ago.
Gun design is a whole other issue. The basic requirements are pretty straight forward: barrel, breech block and locking mechanism, but the details of how they are implemented are sometimes a mystery.
Take any gun apart and you can see how it works, but start examining how all the pieces fit together and trying to figure out what function each little groove and notch serves can be baffling. Sometimes there does not appear to be any point at all. Sometimes the mechanism appears to overly complicated for the apparently simple task it is meant to serve. I suspect that sometimes it is, but it might just as well be a case of "this complicated design" functions reliably, where the simpler design we used earlier did not, and that is something you only find out when you are around for the failures.
Guns are really pretty amazing devices. The basics were pretty much all figured out a hundred years ago (insert mention of the Holy Prophet of Gun Design: John Moses Browning and his self-adopted granddaughter, Tam*). The .45 caliber and 9mm handgun and the 30-06 and 50 caliber BMG all came into existence about then, and are still with us today. Everything that has been done in gun design since then has been minor variations, subtle refinements and experimentation.
Smokeless powder is what gave rise to modern firearms. It produces pressures never before encountered and so opened up a whole new area of technical challenges, which gave rise to some bizarre details found in gun designs.
* thanks to Roberta X for that phrase.
Work
Posting has been a little light lately. I've been working on a little project for Stevens and it is taking more time than expected. The job seemed simple enough: modify the code so that it would compile with the GNU compiler instead of the old IAR one, and make some small changes to the command interface.
I finished modifying the code so that it would compile using gcc over a month ago. As I didn't have hardware to test it on, I tried it out on a software simulator and it apparently worked fine.
Then there were some delays in testing, but eventually we discovered, that no, the code would not run on the actual hardware. So I drag a set of hardware home, start plugging things in and my little empire starts collapsing. First it was the display screen, whose mode of failure sent me down a number of ratholes before I replaced it. Then there was the dead serial port, which I cured with a new hard drive, a new installation on Windows and a USB to serial port adaptor.
Finally got my development environment put together and that's when it got interesting. Timing seems to be everything. Evidently gcc optimizes code better than the old IAR compiler, and so things that worked before, well, now they don't.
We are using an AVR microcontroller running at 4 megahertz (Geez, did you have to hit so hard? That megahertz!). The AVR uses one or two cycles per instruction, so a single cycle instruction takes one-fourth of one micro-second, or 250 nano-seconds. Some of the time sensitive operations operations require delays running from 100 nano-seconds up about ten milli-seconds. Fortunately, most of these times are minimums. It would be very difficult to deal with delays whose upper and lower limits were less than the length of time it takes to execute one instruction.
Update September 2016. Replaced missing pictures.
I finished modifying the code so that it would compile using gcc over a month ago. As I didn't have hardware to test it on, I tried it out on a software simulator and it apparently worked fine.
Then there were some delays in testing, but eventually we discovered, that no, the code would not run on the actual hardware. So I drag a set of hardware home, start plugging things in and my little empire starts collapsing. First it was the display screen, whose mode of failure sent me down a number of ratholes before I replaced it. Then there was the dead serial port, which I cured with a new hard drive, a new installation on Windows and a USB to serial port adaptor.
 |
| New hard drive from Iguana Micro. $70. With Windows and all my development code loaded I am using three percent of the capacity. |
 |
AVR In-Circuit Serial Progammer (ISP or ICSP, depending on who you are talking to).
Cover removed so we can unplug the ribbon cable.
That's a USB cable plugged in the back.
|
Update September 2016. Replaced missing pictures.
I Work On A Starship
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| I Work On A Starship by Roberta X |
She also writes and putting these two skills together she wrote a book, and I ordered a copy via Lulu. It was a little steep compared to the two and three dollar detective stories I've been reading, but then it is special, and so well worth the price. The only part that bugged me was the shipping, and that was my complaint about Lulu last time. They will mail a book for $4, but the package cannot be tracked. Last time I ordered I chose this option (because it was cheap) but the package never arrived. Well, I'm not going to fall down that rat hole again, so let's make sure we can find out where this package goes, so I specify tracking. This bumps the price up to $9 which seems exorbitant, but then I am used to Amazon's shipping rates. I suspect Amazon is only about a zillion times bigger than Lulu, so there may be some economy of scale going on there.
Update February 2017 replaced missing image.
Thursday, January 27, 2011
That Darn Cat
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| Gus surveying his handiwork. |
The plastic bucket is covering a steel surveyor's stake. Ten years ago we had rope hanging from this tree and the swinging path took the munchkins very near this post. I put the bucket over it to mitigate any damage should someone fall on it. Kids fell, the rope broke, but the bucket was never tested. As far as I know.
Update February 2017 replaced missing picture.
Friday, January 21, 2011
Prison for Prions
In today's Jumble I unscrambled one to the words to be PRIONS, but then I realized PRION is probably not in my dictionary, and it isn't, at least not in my old college dictionary. It is in my newer one. Anyway, this made me rethink my solution and I quickly realized the PRISON would work just as well, and being as it is the more common word (half the US population is in prison), it would be the better choice.
According to Merriam-Webster, besides being an agent of death, a prion is also some kind of bird. I've never heard the bird reference before, but the agent of death meaning didn't come into use until 1982.
According to Merriam-Webster, besides being an agent of death, a prion is also some kind of bird. I've never heard the bird reference before, but the agent of death meaning didn't come into use until 1982.
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