Friday, June 18, 2010

Arrgh; or, Made Of Fail

Yesterday was -- with the possible exception of finding a tree service guy with both a clue and affordable* prices -- was an absolutely miserable day. Started with havin' my nose rubbed in the way in which the increasingly irrelevant North Campus of the Skunk Works is no longer anyone's special baliwick, especially mine; true but galling if you happened to be the tech that built it and had (former) Big Wheels tell ya it was your very own to look after. But that's inevitable and one copes by examining one's paycheck. H'mm, not any smaller; okay, then.

Far worse is spending half the day on a project that results in a giant pile of fail and suckage: fought and fought with the position indicator on a servomechanism, attempting to calibrate and set limits, one of those deals where the controls are hundreds of feet away from the thing controlled with no way to see what's happening and at the end of the day, what progress? Why, the total destruction of a $43.01 ten-turn potentiometer mounted in a difficult-to-access location, is what, and without a spare in hand. Now there's a baaaaaad feeling. Overnighted in a pair of 'em and will be standing atop a ladder, muttering imprecations of a dire and icky sort as soon as I can this morning. Only bright side is, the other option for that part sells for $289.99 American, per each.

Naturally, my "alarm clock" this morning was a migraine and a backache. Whine, whine, whine: I figure enough sunshine an' honest labor will fix those things, or at least distract me from 'em. Right? Darn skippy right. (I'm gonna draft me a pair of sharp eyes to watch that 10-turn pot and call out the turns, too. 'Sa pity the folks that made the gadget it's part of didn't believe in hard-limit stops of any kind).
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* As such things go. Tree service outfits after a storm are like the guys who put out burning oil rigs: the work is dangerous, requires well-developed skills and the proper tools, and the clock's tickin' -- the hazard must be dealt with before it gets worse. You are not only paying for the work, you're paying what it takes to have all the workers and widgets available when needed.

7 comments:

Stranger said...

That's why my trouble kit contains a CCTV camera and a 250 foot cable. Someone else' sharp eyes are no substitute for my ancient and much abused peepers. It goes in the boxes with a lot of other seldom used but hair saving pieces of equipment. Like the firemans axe. You never know when you need access - fast.

Stranger

Old Grouch said...

Analog servo control with a multiturn pot for a position sensor? And no end stop? Arrgh, indeed. How old is that gear?

Here's a neat optical/digital one: 30 sensors get you a 2deg resolution, output is a minimum-change code.

D.W. Drang said...

Mrs. Drang has had some success fighting migraines with a beer. Just one sip.

Granted, contra-indicated if you have to go to work afterwards...

Crucis said...

Or, perhaps, once the pot is set, measure across it and replace it with a fixed value. I did that more than once when pots seemed to be getting tweaked by those "who knew not" or by vibration.

Joseph said...

Hope you feel better soon, Roberta!

Roberta X said...

Stranger: yeah, we figured that out this afternoon, after I had the thing working. BUT there are limits to it, as the actual pot gear is tiny and hidden.

Old Grouch, Crucis: pretty new stuff, actually, and it's standard for some segments of the industry. It cannot be replaced with a fixed resistor, as it tells the controller the rotation position of a particular, important, variable dololly (through a little reduction gear). One must find the limits and tell the controller, "Never go lower than n or higher than m and if some tells you to, when you get there, stop and yell for help." But n and m are numbers we don't know 'til we get to 'em. If they are close to the physical limits of the pot and one happens to got a few degrees too far, cruncho!

Ian Argent said...

Inquiring minds want to know - does the dololly pling the inghams?