Possible LTD From Found Tube

[jimlarsen]

Floral foam, such as Oasis, does not melt when it gets hot. It becomes combustible at around 650 degrees F.

Silicone foam is another good choice when you need tolerance for high temperatures.

[Ian S C]

Jim, another one I'v thought of is Pumice (volcanic lava), can be found a chemist shops, in the bathroom section, or in volcanic regions, lying around in places like the edge of lakes, well here in NZ any way. Its easy to carve, and holds its shape. I'v yet to try it. Ian S C

[martinnman]

First, I had to cut the foam of the correct thickness, then the wire is pulled until the desired height board attached to my laboratory for low-voltage DC-foam and slid across the board. Then put a hole in the middle, using a vertical wire, and foam mounted pivot, turn it all ready.

[theropod2]

First, I had to cut the foam of the correct thickness, then the wire is pulled until the desired height board attached to my laboratory for low-voltage DC-foam and slid across the board. Then put a hole in the middle, using a vertical wire, and foam mounted pivot, turn it all ready.

I have the resistor wire and will settle for my one inch thickness. Planing it down is beyond my tooling at the moment. Perhaps if I set up a simple roller, like a pair of drawer rails, but my first priority is cutting the tube squarely.

I just yesterday laid out a nice square tape line to cut the tube, and I'm picking up some new hacksaw blades before I start. That will be Saturday. Should I go for a fine toothed variety?

Whomever suggested the floral foam, good thinking! My next engine using this tube may well employ that, but I have the polystyrene on hand, and plenty to "practice" on.

I will take a few pictures and record the measurements of parts as I go. That may be a chore since I'll no doubt have to modify things as I go. I still have the Airpot® glass/graphite power cylinder in perfect condition. I'm thinking of using water based polyurethane as glue for the displacer tube. I've been eying an old fishing rod tip (already broken from the rest of the rod). I can use slow setting epoxy on everything except the foam. Would a hot glue drop be too much and melt the foam? I have some of that thick aluminum tape for insulating ducts and is sticky as hell on one side. I know most serious glues will melt this stuff to goo.

I still think there is power in the larger versions, like I've cited before, that just about any of us here could build. I'll check and see if the QT movie of that is still stored.... you bet see below, but I do need to take this down soon, so save it now if you're interested. It's in German about some very large LTD Stirling engines shown pumping water.

LINK 11 meg QT movie.

I don't expect my little engine to do much more than spin itself, but I want it to do it with the least temperature difference possible with my material and tools. If I/we can learn the core issues I don't see any reason why any of us couldn't build engines the size of those in the vid. I don't see any rocket science. These look to be using the bellows from a truck trailer air ride system as a power piston/diaphragm.

R

[Ian S C]

Your reference to glue is for attaching the rod to the displacer disc, most glues seem to disolve the foam, so I attached mine by putting the rod through the disc with an aluminium washer both sides. There is a thread on the rod, and a nut top and bottom, the rod on my motor is 1.5 mm dia for a 6" dia disc.
For the saw 18 tooth to the inch would be ok, keep it cool or the plastic will stick to it, just work your way around the tube, it could be handy if you could borrow another pair of hands to hold the tube, put a bit of cloth or similar under it to try and stop it getting scratched.If the blade is too fine it clogs up.
If you have one, a tennon saw (wood work) will work fine, or even an ordenary cross cut woodsaw. Ian S C

[presentteck]

Im making an engine very slimier to this (6 inch OD plexi tube) the thread is here >>> http://stirlingengineforum.com/viewtopic.php?f=1&t=1044

I cut my tube to 1 1/8 inch tall and used a 3/4 inch displacer of foam.
still a WIP, check it out though