Wednesday, July 16, 2014 Hi gang! Well there’s lots going on and as usual I’m late! --First up our pal Ernie Leimkuhler is in town for the week and I’m hoping he can do some sort of welding class this Saturday …if anyone’s interested?? Let me know ASAP!! --Forgot to mention that back on BBQ Saturday Dave Woolsey brought along an interesting idea he’s developing: a way to diffuse light from LEDs. He’s equipped a string of Xmas lights with small glass bottles that attach over the LEDs via heat shrink tubing. Each bottle is filled about half way with small transparent plastic spheres. These reflect the light in all directions, preventing bright spots: very clever. I’ve got an awful photo here: https://flickr/photos/steamboat_ed/14457945148/in/set-72157622894976626 --Sooo last week we had quite a mob and lots got done. Wayne and Bruce Matson worked on a power supply that will be used to run a quartet of VW headlights and taillights thru a bright-dim-blinky cycle. Said VW will be on display at the upcoming County Fair. The lights are being programmed into an Arduino that is sending commands to one of Bruce’s glockenspiel controller boards, fitted with four FETs that are rated for a fair bit of current. These have been attached to heat sinks to keep ‘em from melting their soldered connections. With luck it won’t come to that: they’re cautious builders! --Meanwhile Bruce L spent the evening on the big lathe, with the idea of setting up for threading operations. He brought along a big chunk of steel round bar and made various shallow spiral cuts in it to see what’s what. --Forgot to mention last week Ed and Big Chris got to discussing how one goes about grinding gunpowder to make it as fine as what one sees in firecrackers; the trick being to do it without blowing up! Ed’s tiny .177 cal. replica ship’s cannon just doesn’t work very well using ‘oversized’ pistol powder. Chris said the trick is to buy a ‘powder grinder’: a plastic device that contains non-sparking materials that can be attached to a hand drill. These are available on ebay and Ed plans to get one soon. --Ed finally had his steam turbine to a point where it could be run on air and, once everyone had donned ear protection (that sucker’s *loud*!!) he gave it a run-up using 75 psi shop air. What Ed didn’t know how to do was to determine how fast the little beastie was spinning. A piece of blue painter’s tape on the axle was no help: it just became a blur and there was no optical tachometer handy to measure its passage anyhow. Along comes Bruce M who knew exactly what needed to be done: he got out his iPad and downloaded a frequency spectrum analyzer app. Using the built in microphone he could visualize the note put out by the turbine: most interesting! As it turns out the ‘tune’ has a second harmonic that can swamp the primary, showing up as a pair of peaks in the graphical output. One ignores the higher peak at the higher frequency and notes the lower peak at the lower frequency. For Ed’s turbine this number was around 10khz. Next one divides this frequency by the number of blades on the turbine disk (28) and multiplies the result by 60 to yield RPM: clever! So Ed’s turbine is spinning at 21,430 RPM: yowza! Here’s a link to the build blog that concludes with a short video: https://flickr/photos/steamboat_ed/sets/72157645304226559/ --Mark Jackson brought along a homebrew tube rolling contraption that he and Bruce L have been using. It’s very simple and very clever. It also incorporates a shank that can be fitted into a reciever hitch which makes it ideal for field work where no vise is available. --Ed got his hands on a black light so if we can get Big Chris to bring back the weird green glass that he found at Goodwill we can test it for fluorescence this week. There’s also a possibility that the glass might be radioactive so we’re hoping someone can bring the right gear to run tests. --Terry came along bearing gifts: heaps of spare parts and a load of big-ass capacitors that filled the loader bucket on Ed’s garden tractor! These caps are high-voltage jobs and would be dandy for a mass driver or similar high-joule application. One look at them though and Tom was greatly concerned as some of them appeared to be covered in oil: could this be the dreaded PCB?? At the time nobody knew so it was determined that the best thing to do would be for Terry to take them home again. Now the good news: Mark Hawk has tracked down the manufacturer and got a copy of the data sheet. These caps have no trace of evil compounds within and are in fact filled with nice safe mineral oil! We’re hoping Terry brings the caps back tomorrow evening so that eager hands can grab the swag for numerous projects. --Well that’s about all I remember; fill in the blanks if I left anything out, eh? Photos of recent shenanigans are here: https://flickr/photos/steamboat_ed/sets/72157622894976626/ --It looks like Mark H won’t be making it this Thurs so we need an alternate burrito-fetcher! Or should I just snag a pizza? --Next gathering: tomorrow night! Come early, stay late get stuff done and don’t forget Ernie’s in town and let me know ifyawanna get some first rate welding instruction.
Posted on: Wed, 16 Jul 2014 17:31:50 +0000
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