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| Potty Popcorn Engine |
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| sbwhart:
Thanks Andy/Dave Dave I think Marv has a programme for working that out on his web site. Made the eccentric sleeve over the past couple of days, every time I make an eccentric sleeve I seem to end up making it a different way than the time before, I think that comes from making them from whatever material I have around at the time. For this one I had a tub end from a bit of 45mm bar. Started off in the lathe faced it off, centre drilled it and stuck a 1/2" drill down it. Then keeping it on the chuck transfered over to the RT centered under the mill spindle, and with a 3mm slot drill cut the shape out. Whilst I got it centered scribed a line across the middle, this will help set up for drilling a splitting. Then back over to the lathe things were a bit tight for room but managed to part it off:-still got enough of the stub of bar left for a flywheel sometime. Then using the scribe marks lined it up level in the mill and drilled and tapped the holes. Then with a slitting saw cut it in half. Then set it up in the four jaw, using my centre height gauge get the split on centre, its more important that you get the split centered than getting it exactly in the middle 90 deg from the split. And bored it out for a good fit on the eccentric. Her it is assembled. Stew |
| andyf:
--- Quote from: Stilldrillin on October 16, 2011, 04:37:30 AM ---While we're slightly mathematical......... :smart: Discussed, some months back. What was the thickness of packing needed in a three jaw chuck, to throw to the required offset? :scratch: I seem to remember a simple reply. (Like 2 or 3x throw)..... David D --- End quote --- See this page http://www.steves-workshop.co.uk/tips/lathetech/eccentrics/eccentricindex.htm Andy (Andyf, this time) |
| madjackghengis:
--- Quote from: sbwhart on September 30, 2011, 01:14:45 AM ---Thanks Nick/Arnold/Dave/Saw --- Quote from: NickG on September 29, 2011, 10:43:42 PM ---Stew, very nice ... a lot of work in that part there. I've often wondered how people did that, nice method ... guess it's one of those that although taking more time to remove metal, it's actually easier done from stock than casting. Nick --- End quote --- Thats a very good point Nick, I had been wondering myself how you would machine it up if it had bin made as a casting, and i just couldn't see how you would hold it. Had a good natter with John the other night about making this part and he suggested that you could make it in two parts and silver solder it together, which I think would be very veasable also. Stew --- End quote --- Having taken great pleasure in watching this engine come together, and admiring the real ingenuity shown in working the parts to their final size and shape, I just want to say, working with castings is slightly different, but by no means more difficult, it just follows a different path, using fixtures and means of holding adapted to the castings, and it comes with the knowledge one doesn't have to empty out all the excess metal hidden inside, and often, the very design of the casting makes for the least amount of material removed, making the holding of it easier, because less force is necessary for the machining. I enjoy making parts and whole engines from blank stock, but I've found similar pleasure in the use of castings and building, and find each has its advantages, and both being a gratifying exercise in engineering. I only hope I get to the point of making patterns and actually casting my own parts, as that seems to really mean something to those who we watch do it on this site. I know I'm impressed by much of the skill and ingenuity shown by those who have cast every part of their engine. Don't think for a moment I would take away anything from the skillful work you are showing in this build log, it is a work of art without a doubt. :beer: Cheers, mad jack |
| AndyB:
Not complicated??? :lol: :lol: :lol: My mate from Wisbech (they are all like it there) Andy |
| Stilldrillin:
Andyf. Thank you! :clap: :clap: That's the one I was thinking of........ AND, I can multiply by 1.5..... If me calculator batteries are still ok! :thumbup: Tother Andy. If they're all like that in Wisbech..... They look a happy lot. And they've still got all of their fingers! :D David D |
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