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| Jan Ridders' Simple LTD Stirling Engine - craynerd build log |
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| raynerd:
Yes, me too MadJack. My lathe is currently burried under tools while I re-organise my workshop .I should be finished tidying by weekend and I`ll try again then - I think I needed a break from it anyway. You know the steel wool - how does it stay in? I can imagine the stray whisker popping out and causing a problem! Thanks for the motivation. I`ve not given up, just a short break! |
| NickG:
Just seen the video Chris and it's almost running! Not far off at all, I had a Kontax one like the one David D showed us earlier in the thread and the moment of inertia of the flywheel on that was way higher than on yours - wonder if that has much bearing on how easy it is to get them to run - possibly better with a higher moment of inertia although obviously the ones with CD's for flywheels have been proven to work too. Did you try some ice cubes on top plate? I think it might run just with a bit more heat, it's nothing more than fine tuning any 'tight' spots and possibly that displacer. Nick :thumbup: |
| madjackghengis:
Hi Chris, the steel wool must be pushed and prodded into shape so it basically holds its own shape, with the holes in the foam providing a perimeter, and taking a needle or fine set of tweezers and weaving stray fibers back into the pad with some super glue to get the last stragglers to stay in place. I'm curious, have you run an indicator around the test tube power cylinder and checked it for oval and taper? I'm not sure how the test tubes are made, but I'm pretty sure they are not a ground finish inside, and you may well have less than a good piston seal. I've got an "air-pot" dashpot, which is a ground glass cylinder with a graphite piston, intended to act as a shock absorber in some sort of electronics equipment, I got it as a "free sample", by mailing a card in, and the piston will stay at the top of its cylinder for hours with very little discernable drop, if the port is plugged completely. It takes about twenty four hours to drop down if left totally alone. If all else fails, I would try using conventional lapping techniques and lap out the power cylinder with perhaps a wood dowel lap, and very fine carborundum lapping compound, which is also a rather good way to see exactly how straight and round a glass cylinder is, as well. I've found with my little flame sucker, it can easily be a dozen problems all at the same time stopping it from running, yet needing each and every fix, and not allowing a single one go undone and still work. I questioned whether the new cylinder with actual head fins was necessary, after fixing everything else wrong, and put the old cylinder back on, with all the other problems still fixed, and while it was better than previous, it still did not even try to run, and immediately after putting back the new cylinder, it ran the first time I spun it over. The only thing making me certain it was my problems, was the fact I've seen an engine exactly like mine, but with a quarter inch bore and a seven sixteenths stroke with a quarter next to it for size, just sitting there running a few thousand rpm like it was no problem. I hope to see your LTD engine running like a top, soon. I'm sure you'll get it all worked out, and you will know exactly where you fixed the most important impediment when you get to it. :thumbup: mad jack |
| cidrontmg:
Heh, MadJack, not trying to steal craynerdīs thread, but the head fins in the flame licker are vitally important, like I told you elsewhere... I canīt be of much help with the LTD, having never built one myself. Although one is in my projects list. But from the videos it seems that itīs actually producing some power, but not enough to sustain the entire 360* rotation. So, you need more power, and less losses. More power= bigger heat differential, "tighter" power piston. Less losses= reducing friction in the bearings, linkages, wherever it might feel tight. Just one thought. Instead of a CD, I might try using an old hard disk platter, for the flywheel. They come in two varieties, metal and glass disks. Either one would have far greater a momentum than a polycarbonate CD. And Iīm sure you get a runner, itīs not missing much. :wave: |
| madjackghengis:
Not to steal this thread myself, but I must admit you were absolutely spot on, with regard to the head fins, cidron, and as a matter of fact, I took the engine and mounted it to the cylinder head of a ten horse Tecumseh engine which died, just to get the extremely greater heat dissapation the head fins give, and the engine runs essentially till I shut it down. I would second that motion for a hard drive disc for the greater flywheel weight and effect, the videos both show the engine is very close to running, and just lacking the last little bit. Powdered graphite is sold for use in locks for doors and such, and a tiny bit on the displacer shaft and in the power cylinder could help a bit. As cidron says, you are definitely close to having a runner. :headbang: mad jack |
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