One year ago today: May 17, 2014, Descartes quote.
Five years ago today: May 17, 2010, deity mill?
Six years ago today: May 17, 2009, cheap ass cell phone.
MORNING
So much for my taking the day off. A looming storm to the northeast and the most complicated club meeting ever finds me back in my comfy chair by 10:00 AM. How come, whenever you see clouds on the horizon, the storm is heading your way? It’s probability. You would not notice the clouds unless they were getting closer. The meeting was about gear ratios, something you may have predicted was due to happen. And this was no easy affair, gears are not intuitive to many otherwise clever people.
My goal this morning was to calculate and build a gear train with the ratios were 1:60 and 1:12 or 1:24. This would demonstrate mastery to the point of being able to build a clock if need be. Anybody could build these gears with a little know-how, but my challenge is to fit the gears into the smallest possible space. I believe, with my background, I can find the correct ratios that minimize the size for the gear train. The other codicil is that I am permitted only one driving gear.
That’s gear ratios in a gear train, not the easier count-the-teeth two gears. The Internet doesn’t tell you what you need to know, so my wooden models were a big hit, particularly the multiple gears on a common shaft. Proof that they do not turn at different speeds, which was the source of the complication just said. Here’s more things they don’t spell out:
Compound gears are normally idlers only – existing between two other gears
One compound gear is the usual maximum due to friction loses. (Exception is clocks.)
The teeth on the common shaft gears do not require common denominators.
Result? Mass confusion. Even when handling the wooden models, some people still tried to turn the gears at different speeds. Worse, everybody except me was not feeling well and I was eight minutes into the presentation before somebody admitted they didn’t know what a prime number was. If you make a gear with 7 teeth, as most sources on the Internet quote as a minimum, you are a fool. Because the next multiple is 14, then 21. That’s why I chose 9 teeth. Easy to calculate.
And it appears this calculation will perpetually be left up to me. Is there are flu going around? Even Agt. M did not finish his food. Not a good sign at all. He left bacon on the plate. Yes, folks, when people turn away from free food on Sunday, it must be some sort of epidemic. I was afraid to even bring up the final topic, two gears on a shaft that can counter-rotate.
Another gaudy preference turns out to be that dreadful green gear paint. They like it because it makes the gears stand out. Yuck. Good thing I only have a half-gallon. To those who noticed, this is not a commitment to build gears or clocks, the relevant phrase being "if need be". It is well-established by now that mainly due to expense, most projects are taken only to the stage where they could be built "if need be". Robots, clocks, airplanes, even propellors, will likely never be constructed. Unless I win the lottery.
NOON
“ It is best to remain slightly suspicious of people who line the walls with awards and pictures of their family.” --Me. I said that. I’ve heard other versions; this one is mine.
Today, we learn. Like celestial navigation, there are formulas to follow, but it is best if one knuckles down and learns the derivation of each variable in those equations. So yes, there are times when I walk on my knuckles, Ken. I’ve got the gear ratios in my head, now to put pencil to paper and work out a hundred examples. I’d also like to produce a quick tutorial and publish it, since what is already out there is awful. Inadequate. COIK.
I still have no new camera, but like women, it is not the availability. It’s that there are so damn many bad models that don’t do the job right all over the place and the few that might work are bloody expensive for my needs.
For something to do today, I’m turning to that oak for another purpose. Wooden gears are tough to make exact—notice to all that I did not say they were “knotty”—and need a breaking in period. I’ve designed a contraption to do just that. Alas, the driving gear wears out just as fast as the driven gear. Hence, I should make that all-important driving gear out of oak. Plainly, the larger the gear, the better, but I don’t have any large pieces of oak.
Drop back another day to see this interesting apparatus at work. A motorized gear on the bottom has a bracket above. This bracket matches the axle size of the new gear (normally a standardized 5/16ths around here. By dropping the new gear into the bracket, gravity holds it down against that driving gear and let ‘er fly. Outdoors. This can be a dusty operation at times.
If time permits, I will also make a demonstration set gears using 9 as the base. So I mean the number of teeth as 9, 12, 15, 18, 21, 24, 27, 30, and 33 and 36. You can make any ratios, but these multiples but this set can be combined to almost any interim number for learning.
AFTERNOON
Okay, is it 5:00PM already? I learned several things cutting this new master gear. You ready? Oak smells nice when cut. I wish I could remember where I’ve had that aroma before. Not at the furniture plant, which did not use any oak. Oak is hard, not any connection to hardwood, which I don’t know about. It cuts finely and smoothly. It has an even grain, but that grain is crossways to the purpose I need it for. Am I saying oak is mainly for show?
This, alas, is not samples of the real wood, which I would consider buying, but a mere poster. And they want $25 for that. Plus shipping. Their heads must be made of material 7.
Lignum vitae, the Florida tree, it turns out, was highly prized for making gears and bearings. Cook used it for his original clocks in London, preferring it over metal. Used for bowling pins and cogs on waterwheels, it is reputed to be self-oiling. This is what I need, but where to buy it? Is it an endangered species?
During this spin-off research, I learned that some places like the River Medway have a thousand year history of watermills. Most that exist today have been converted to private residences. There were some 64 mills on this single river, one of which is still operating, but I have no time to find which. At some point over 200 places on this river were used for some type of water power.
Later, yes lingum vitae is endangered, so BB Rich guitars, mind you what happened to Gibson when they voted for the wrong political candidate. It is heavy, difficult to cut, dulls saw blades, is the hardest wood known, won’t take to glue, and sinks like a stone. There is no information on how well it clubs political candidates. But I believe all thinking people would like to find out. What? I said "thinking".
I further learned that fake wood is big business and a wood database of florescence is being developed to ID what is genuine. Here is an interesting video of the process.
A block of Argentine lignum vitae, the only kind still legally available, for a block 3"x3"x12" will cost you $38. Plus shipping. More material 7?
EVENING
Here’s the best gear I’ve ever cut. Solid oak. I stayed up late and finished the “gear roller” only to discover at the last moment that old fan motors are nothing to write home about. They are gutless, but one can work with that. Anyway, the concept works fine and this gear is the star of the show. It turns out the spacing and angle of the gear teeth is more important than a polished look. By angle, I mean the slight “inward” bend of the gear when cut.
If you have a sharp eye, you can see the difference between this gear and the prototypes. As it happens, in the upper center of the picture is one of my first attempts, you can see how sprocket-like the gear teeth are. Very inefficient and noisy and as you get fewer teeth, the inward bend of the cut is more pronounced. Shown here, I am fitting the oak master to a more recent cut, you can see the finer mesh of the teeth.
As for the oak gear, it is about the best that can be made with my existing equipment. It is above any standard needed to produce a working robot provided the robot was not meant to last forever. The on-line tutorials stick to plywood gears, so this is the first non-plywood version I’ve made. Just picking it up reveals the oak is quite superior in hardness and quality. The plan is for the gear roller assembly to break in new gears against this master gear rather than each other.
The reason is mainly sawdust. The laminate layers of plywood seem to have minimal strength in themselves, so the running [plywood] gear train throws off chips as the parts wear in. If I didn’t say, this can further cause a bias of direction. Everything runs smoothly until you reverse the motor, the easiest way to reverse movement in robotics. It’s like the nap of a carpet. The gear train will jam, which I used to get around by the tedious process of flipping the gears over and wearing them in a second time.
This gear roller will hopefully take care of that. Why? Because it is time to move on to something more complicated. I’ve been re-reading motor control again and the material gets easier to comprehend each pass. It turns out I’ve lucky to have not burned out any of my Arduinos. By following the directions very closely, I had them hooked up wrong. And yes, I read the whole chapter, cover to cover, before proceeding. Been doing that since grade school. Cover to cover, every word. And in 2010, it took six months to save up for that first Arduino.
I had kind of guessed that these microcontrollers were just one step in the process, albeit a critical and complicated one. It’s a giggle how many thousands of Arduinos are out there because the owners have nothing to connect them to. Five years ago I would have thought America was full of engineering hobbyists who had lathes and punches and would be raring to go over a new product or invention. Ha, guys, in the end you quit going to meetings and learn to do it yourself. Progress, my eye. Internet, my eye.
And as for getting any worthwhile help from Generation X, Y, or Millennial, my foot.
ADDENDUM
All of this will be on the exam. Here is a photo of the gear train that gave so much grief this morning. It is possible I was spared that learning curve only because I built the gears, giving myself no prospect of not understanding the workings. (There is also a picture of the comparative treatments of the dead tree from the bakery as I try to find out why the wood had no grain.)
You may notice the small 7-tooth gear, which has two problems. One, too few teeth meaning it is awkward to always keep one gear tooth engaged until the next one “bites”. If you didn’t know that, neither did I. You always want the new tooth to take hold before the old one disengages. Two, fewer gears than 9 produce a noticeable increase in “clatter”. Unmistakably visible is the citrus green gear paint, which also dates these as recent manufacture.
In the short time I’ve made gears, my early production is obsolete. Despite using the same templates, my lack of experience shows and for some reason they don’t mesh right, always finding a position they can jam, or sometimes just will not run backwards, a robotic necessity. See, you are smarter than Nova already.
Now the wood experiment. Alas, I had to cancel this one. The photo shows various tinctures and stains used to see if I could find the grain. No luck, but the real reason for discontinuing this research was lack of a microscope. Whatever killed this tree did so at a molecular level that I cannot magnify by any other means over here. More people liked this little plaque which smelled of vinegar.
Jackie Wright. That’s the name of Benny Hill’s sidekick. The little bald-headed guy Benny was always slapping on the head. He was Irish and recruited by Benny Hill specifically for the part.* Um, America, you have never seen the real Benny Hill Show, which would be censored in this country. Not for pornography, but for racial humor. Even the famous “fluctuations” word is edited out of what you are allowed to see.
He [Wright] was 4-foot-11 and became the most famous stooge in British entertainment. A chain-smoker, he later had Alzheimers. But what a success, he worked his way up from one of twelve children whose father was a laborer building Cadillac cars. For reasons unknown, it is quite difficult to find any pictures of this actor on the Internet. But he must have died wealthy, as he was with the BBC for twenty years.
I miss the old Benny Hill humor. My stance on racial jokes is fundamental. While some of it is off-color, there must be a reason people laugh. While there is a time and a place for everything, generally speaking those who cannot take a joke are worse than the joke itself. For all I care, racial jokes and racist jokes might not even be the same thing. If the first ten cowboys you meet are alcoholics, exactly what are you supposed to think?
*the part was called "our little Donny Osmond", another of Hill's classic insults that never made the American media.
Last Laugh
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