One year ago today: July 30, 2014, Kraft inflation.
Five years ago today: July 30, 2010, for your convenience.
Six years ago today: July 30, 2009, another legal scam.
MORNING
What’s this rumor I’m hearing that the media is gagging the news that Hillary or somebody held a rally and only 32 people showed up. I say it is just a rumor. But I hope it isn’t. America has had enough of the “establishment”. Then I fell out of my chair (really) laughing when Trump told the story of how Romney tried to garner votes by doing his own shopping but couldn’t figure out how the automatic door at the supermarket worked. All caught on video.
Next, I got together the basic parts for my stepper linear contraption. Man, these things are really accurate. But I don’t know how to use the files that make them do anything. I can, of course, program the motors and movement. And I’ll hook up an old drill. At this point, I will just be happy to get the thing to guide itself into position.
Those who’ve been here before will recognize the Arduino and the board I mount these on long before the factory version of this original idea came along. You can see the small stepper motor, this is one of the six from Hacktronics. They are capable of half-steps, so are considerably more accurate than they need to be. The drill stays stationary, it is the table under the drill that moves with precision.
These are great tasks for mental exercise, the element that is missing from television. Figuring out how to make it mechanically right is a lot like solving a maze. You wander down blind alleys until it hits you. While I’m proud of the tools accumulated, often a single item like a bearing fitting requires a special trip to the Home Depot for a drill bit they usually don’t have. Harbor Freight is 5.5 times the distance.
The new guy, Serge, we’ll call him, is a complete beginner. It’s the same tale from the trailer court. Circumstances found him in possession of a quantity of computer parts and such that he did not know how to use. The fact that he even got curious about it is a good start. And it makes me look like an expert. Don’t buy 1/8 watt resistors. Download the IDE before you buy an Arduino. Learn transistors first. I guess in that sense maybe I do know a lot about the topic.
Note that for the club, the precision manufacturing, such as it is, continues to be done in-house, right here. Not at the clubhouse. We do not regard the welding we do as a precision operation.
NOON
By noon, I was fitting the (roller skate) bearings to the drive rail. I promise a clearer picture below, but for now this shows the procedure to get the drive rail to rotate in place with the least effort. This is because tentatively, this unit would have a portable memory batter supply, though the drill motor would require mains (110 volt commercial power).
Don’t read too much into this photo, since there are other pieces shown that are not part of the design. Such as the ball caster, which was not needed soon after this picture was taken. You’ll see the importance of the copper pipe and end caps in a moment.
Another first, a club meeting over the tracks and in a McDonald’s. The reason was kind of unorthodox. The Radio Schack reorganization saw them spread unsold stock around. Now the sad part. You can tell the general IQ of an area by how fast the robot parts sell. The more stupid the populace, the more chance of finding deals of up to 70% off. That area around 441 and Miami Gardens must be inhabited by escapees from the nearest FEMA sterilization compound.
The new guy lives near the McDonald’s and the Radio Shack, so I called the meeting up there. He showed up with all manner of gear that has long since sold out everywhere else. Plus, he guessed mostly right.You’ll find me up there in an hour, get me some goodies. I deserve it for surviving inside a McDonald’s for nearly 90 minutes and having only coffee. It’s willpower, lads, I just got back from two out-of-town trips without breaking my diet.
The lack of bookstores found me browsing the rack at Goodwill. Hmmm, an old lady, or I guess I’m supposed to say past her prime, moves on me. Oh, this author is great, that one is superb. Well, I know they aren’t but okay, so look at her. About 12 to 15 years younger than me, but definitely a lost cause. Do you know what bat wings are? She wasn’t a looker even in her pre-menopausal days. I had to defuse this one rapidly. So when she asked if I was looking for anyone in particular, I said, “Taylor Swift”. (Worked like a charm.)
Don’t worry, if she had made an excellent come back on that, I’d have bought her dinner. Sorry gals, guys like me don’t swing from trees.
AFTERNOON
I drove home in the blast furnace and not to Radio Shack. No twenty mile trips in this heat. Instead, I watched old documentaries, although I should not say old, as many of the archived newsreels have only recently been declassified. I was doing some mental gymnastics over this proposed automatic drilling table. It is the only way I will ever drill 1,000,000 holes 3/32nd of an inch in diameter. What on Earth do I need a million holes for? Those who read back far enough will know. I presume that even my critics, who no doubt have their own project needs on a similar scale, will understand.
On that platform will rest a similar, but small (shorter) set of rails 90° to the ones shown. So essentially, what is shown here will move my hand left and right, the upper platform (not built yet) will move my hand toward the top and bottom of the directions shown in the photo. For the mathematically inclined, that’s the X and Z axes, the Y axis will mount an overhead drill. In theory.
This is a fairly complete photo of all the parts you won’t see once the device is complete. So, let’s look at the same thing from a mechanical point of view. Starting in the lower right and moving diagonally toward the upper left. First you see the Arduino, which has wiring to a small black interface board. From that, you see small wires to the stepper motor. These motors are surprisingly tough, you cannot “stop” the shaft by grabbing it with your fingers.
That shaft goes through that upright wooden block which houses a shaft coupler made from old garden hose. Those things may ultimately leak a lot, but they are tough. This turns the shaft left or right, depending on motor control. From this part in, those who have seen or used a CNC machine will probably recognize what’s going on. I have never seen such a machine myself. But this is the part that captivates me. I’ll explain in a moment.
It is difficult to see, but this shaft rests on the bearings and as it turns, there is large “rod coupler” nut that does not turn. The spinning of the shaft, instead, moves it left or right. Actually, if you look very closely, you can make out part of that rod coupler just below the first knuckle of my little finger. This is the working part.
Now for the explaining. This shaft has 32 screw turns per inch. That means the thread “moves” one inch each time the shaft is spun 32 times. The standard Arduino stepper motor has 200 “steps” to make one revolution (hence the name “stepper”). When connected, it means the Arduino can handily control increments as small as 1/6,400th of an inch (32 x 200). This is far beyond any precision I’m likely to require.
There is an interesting aspect to the Arduino. Most programmers know what an interrupt request is, but are loathe to use it. The reason is it resets the chip timer (um, that’s the easy explanation). However, once I learned the PCM pins use a separate timer, I got to thinking how I can control half-steps. That means a resolution of 1/12,800th of one inch. I’ll mull over the implications of that, but I don’t think I even have equipment that can see anything that small.
The challenge with the code is to get one Arduino to operate two steppers. Like Ken Sanchuk, the microcontroller has the mentality of a one year old and can normally do only one simple task at a time. But by interrupting that, you can trick them into doing two—as long as they don’t suspect a thing. The most expensive component in the diagram is the Arduino, at $40. It is worth trying to use only one. I have, in the back of my mind, an idea how this can be done.
What? Well, Ken, next time pay back people the money you owe. I mean, being a winner isn't that difficult.
NIGHT
Aha, now I’m glad I dug out the ROM device, the one I wanted to hawk to science fairs when Hacktronics went under. Now that the gang knows much more about electronics than in 2012(?) was it, the project makes great sense. Now it is fascinating. We held an impromptu meeting until 11:52PM on my porch last evening going over details. We do have an electric bike we can sell for around $150 profit each, but it works out to minimum wage after assembly.
That being said, the rest of the crew has minimal concepts of what it takes to make an idea successful. Asking questions like where is the next science fair? How should I know? Oh, well, how do I expect to sell these kits if I don’t know? Boy, these guys can be at a kindergarten level. When I tried to explain how I had contacted a major science fair supplier, I lost them. And of course, why have I not thought of painting the toothpicks different colors. Gee, I dunno. Just dumb, I guess.
Yep, I’m dismayed at having to answer the same unthinking questions every time, but I’ve often thought that is why mad scientists become recluses. I’ll tell you what, if this drill table becomes another winner, I will consider showing up back and Nova and rubbing their noses in it. And it only has to look like it is working to be a success.
Author's note: I shall try to get some new pictures of the ROM device. It is entirely home made, yet I still get many unbelievers. That's rookies who don't believe it isn't a kit and users who don't believe it is accomplished entirely without logic circuits. Nothing but diodes and resistors. I'm not about to try finding the older pictures, as these photos are not carefully cataloged like the blog text. There are around 15,000 photos plus another equal number of unused items filed only by general month of publication. I'll say it again, this blog was never intended to include photos. They are only here because of the advent of cheap digital cameras.
ADDENDUM
What happened to the rat, Houdini? Smart fellow, right after I bought the Nooski, he disappeared. Makes sense, since there isn’t really enough available food in my spotless kitchen. Until 6:01AM today. He’s back, but not where I had placed the trap. From here on, it is me vs. the rat. Who shall prevail? Stayed tuned for the answers to this and many other important questions. If he gets away even on more time, I am changing his name from Houdini to Hillary.
Last Laugh
(The label says it’s a feminist detector.)
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