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| Stirling Engine ... of sorts .. |
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| Bluechip:
Thanks for the replies folks ... bit more progress ... [1] That transfer tube thing ... which requires two banjos fixing at right angles ... and in the correct place .. One idea was to soft solder them on in situ ... but all I have is the electronics 60/40 stuff ... serious doubts about that. Another alternative is tinmans solder ( comsol ??? ) which has a higher melting point but it's not cheap and I have no other use for it AFAIK. Then I found out about JB Weld Steel Reinforced Epoxy. This appears to be OK up to 315oC. Having got some I tried it out. Bit of 1/4" brass round, tickled with steel wool to clean it, poked a a 1/4" hole in the end a bit of 5/8" x 3/8" steel flat and epoxied the two together. Just pushed in and rotated a bit. Left it for two days .. Scrounged Norm's Infra Red thermometer, [ nice, must get one, new toys always welcome ] applied propane torch, thermometer said about 430oC , well, it did come apart with a good heave via a 10" adjustable, but I would guess about 40 ft/lbs. Remarkable product, not cheap, but then neither is solder ... I doubt if that tube will get anywhere near 300 odd C in free air. So, the tube is now epoxied together. Good enough for me, chief. We're in business... Made two gaskets from .25mm PTFE sheet, as per Bogs' write up elsewhere in MM.. Cut out with an OLFA Compass Cutter and the screw holes done with Maun hole punch pliers. I do have some small wad punches, but they made a hideous mess, so got a new tool ... [ toy ] [2] The displacer guide bush leaked like a sieve .. should know by now steel bar is undersize, and reamers cut oversize ... So that has been remade, this time the 5/16" shaft hole has been bored out to suit the actual 0.309" which passes for 5/16" rod .. A lot better, couldn't have been much worse actually ... Tried the warm it up and see bit, when the displacer is pushed in and out there is quite some push and suck on the power piston rod ... Maybe the Gods are smiling on their humble servant ??? BC |
| doubleboost:
That is a very nice looking job I do like to see nice bends in pipe work :clap: :clap: :clap: :clap: John |
| Bluechip:
--- Quote from: doubleboost on September 18, 2011, 03:43:14 PM ---That is a very nice looking job I do like to see nice bends in pipe work :clap: :clap: :clap: :clap: John --- End quote --- Hi John So do I, ... now I've done it. :thumbup: Not so keen on looking at all the wrecked tube in the crap bin .. That bender works quite well, was going to make one years ago with alloy formers etc. then decided to see if PVC would work, being a cheapskate. It does, for copper tube anyway .. Quite chuffed .. BC |
| madjackghengis:
Hi BC, while I'm a big fan of epoxy, it never is finished setting until it has turned to dust, in reality, and heat is what determines the time of its demise. As a former electronics tech, I've long used top quality eutectic solder, 63% tin, 37% lead, rosin core, and while it is not recomended for structural use, I've found that it only matters when one gets into large scale use, and the fact eutectic solder melts at 361 degrees F, and is liquid until it solidifies suddenly, at the temperature it freezes at, it is the easiest to use when wicking is important, and is good for almost any use but a steam boiler, where temperatures in an area could go above that degree, and where silver solder is the minimum reasonable. In most model building, it is as strong as any other, as long as one doesn't push the envelope with it. I also use it to tin copper and other metals when I'm going to use a low temperature silver solder, as it is a better wetting solder, and will be displaced by the silver solder when it is applied. I use zinc chloride for flux, which washes clean with water and is an "active" flux. A "eutectic" alloy is one where the metals are a perfect match with all the different molecules being completely mixed. This makes for a solder which goes from liquid to solid rather instantly, and vice versa, where a solder such as fifty fifty will melt slowly, going through a stage of mushy solid into slushy semi-liquid, and then liquid, and do the reverse on cooling. It is good for a "wiped joint" such as using it to connect lead piping, but it can easily leave crevices in the crystaline structure that seep if one works it too much, or moves the parts before it is solid enough. I look forward to seeing this engine completed, and watching it run. It's a looker, and appears to have lots of personality already. :beer: Cheers, mad jack |
| Bluechip:
Hi Jack In retrospect you're probably right about 60/40. It's not actually holding the parts together, just there to block the holes .. :thumbup: Still, it's epoxied in now, and we shall see. If the epoxy lets go, no big job to re-do it. Not done much today, miserable backbone giving me some grief again. Just milled the crank supports to the correct height. Only roughed out in the pics. BC |
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