tag:blogger.com,1999:blog-1798378093674256104.post3671919298217809972..comments2024-03-09T22:40:38.328+10:30Comments on 120 things in 20 years: Stirling engines - Adjustable Stirling engine crankshaft120 Things in 20 yearshttp://www.blogger.com/profile/17936923519713138582noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-1798378093674256104.post-41990895721289306262013-05-31T14:53:13.710+09:302013-05-31T14:53:13.710+09:30I'll use the adjustable crank to set the limit...I'll use the adjustable crank to set the limits and then create a proper one based on the result of the adjustments. <br /><br />Getting a bent wire crank just right is actually quite tricky. Even if all I had was the brass mounts to allow me to remove the crankshaft to bend the wire. it would be worth while. It's very difficult to make adjustments when the shaft is in place, and once the shaft gets out of true, it never runs quite as well. <br /><br />Trying to bend the wire based on measurements as you build the thing doesnt really allow for getting the displacer as close to the top and bottom as you can. <br /><br />No doubt everyone who isn't me will have a better standard of production, and might actually be able to use a ruler :)<br /><br />Also the adjustable cam will allow me to gradually wear the hole in the top of the displacer in some controlled way. Once you turn over the engine with the crank adjusted to too big (almost inevitable when you are trying to bend the wire in situ, the hole for the displacer wire will always be just a tiny bit bigger than it should be. <br /><br />Even if the entire adjustable thing is going too far, I really recommend using a removable mount for the cam shaft so you can pull it off to adjust it, or replace it. <br /><br />Making the shaft supports from wire also allows a stronger material for the bearing surfaces than holes in the tin can. I use a spool of stainless steel welding wire to make the eyelets. Very smooth and very hard. <br /><br />Counter weight on the flywheel, and a stable base should go some way toward keeping the thing from shaking itself to bits :)<br />120 Things in 20 yearshttps://www.blogger.com/profile/17936923519713138582noreply@blogger.comtag:blogger.com,1999:blog-1798378093674256104.post-21933906237515594792013-05-31T01:01:59.356+09:302013-05-31T01:01:59.356+09:30The length of the cam offset should be half of the...The length of the cam offset should be half of the 'stroke' the displacer takes. This way it can reach top to bottom in one stroke. The cam with a half-stroke offset does the whole 50% above and 50% below the centerline.<br /><br />The longer the stroke, the more power (torque) and slower running the engine goes. The shorter the stroke, the less power and faster it goes.<br /><br />For really fast movement, you want really small parts as they have less mass and the engine won't try to chase you across the room with all it's rattling around a heavy displacer would create.Anonymoushttps://www.blogger.com/profile/06488676201737328354noreply@blogger.com