Piston fabrication technique

[surgy]

Hello, my name is Surgy, I have read every post on this forum. I have been bitten by the bug and have started to build my first thermo-accustic type engine. Well I simply cannot get enough information on the matter!! I love these things. So first I will tell you my plan for my engine followed by my piston fabrication technique which I have yet to see done anywhere else. Most people have been using either AirPot products or JB Weld pistons, I use an easier cheaper way.

Ok so on to my design. I am making the typicle run of the mill "lamina" engine for my first go. I decided that I should learn how to drive the car before inventing the wheel. I have a 25mm X 150mm flat bottom brociliate (Pyrex) test tube on its way in the mail with a cork stopper to match. I have a six inch long 3/4 inch ID copper (Repair Flange) that I cut into a 1.75 inch long peace. It was allready polished to a mirror finish inside and out when i got it so no need to do anything else to the cylinder(am i right here?). When the tube arives I will be filling it with an 80mm long wad of Steel Wool. The Steel Wool will start 20mm from the tip and go down. I will then shove the cork stopper as far as I can into the test tube and then cut, groove and otherwise widdle the other end of the cork so that my cylinder will make an air tight, tight sill. I will then poke a hole through the middle of the cork to serve as the "baffle" and presto I have a lamina engine!

I plan on using the spindle and platters from an old HDD for the flywheel (is a flywheel even necisary?). Does anyone have any suggestions on what to use for a connecting rod? How should I connect it to the flywheel? Ok now on to the piston fabrication......

There is a type of putty called "Plumbing Epoxy Putty". It is gray with the viscosity of play doe and when you "kneed" it it mixes with a paste in the middle and changes a darker grey. From this point you have 5 minutes to do the magic. Role the putty around in your hand until you have a ball with no creases or seams. You have your cylinder end down on wax paper right? Ok smash your putty into your cylinder as hard as you can an smash all the walls. Wait two minutes (it's about half as hard as wood at this point) and pop it out of the end of the cylinder. You now have a perfect cylindricle block of hard grey stuff thats air tight in your cylinder. Before it gets hard poke a horizontal hole through the piston (for your main pin that will hold your connecting rod in place.) next make a grove perpendicular (at 90 degrees ) from the hole and make the groove deeper than the hole for the pin so that your rod can go down deeper than the pin (so the pin can go through the rod) and make sure the rod can wiggle back and forth (to oscilate with the flywheel). And presto you have a nice piston with a machined look that can with stand flash temperatures of 500 degrees and constant temps of 250 degrees farenheit. I made a very nice piston and still have 3/4 of a roll of this "putty" left (probably enough to make 6 more pistons). It cost me $3.76 at steves tools, I heard Harbor Freight has it for $.99.

There see I read through every article and felt like i took something (knowledge) from the community. This is my contribution back, thank you for giving me a new hobby and thank you for reading my article, hope to see you around!!!!

PS: any comments or suggestions would be greatly appreciated! thank you.

[Longboy]

............Looks like you will have a basic lamina engine. Haven't heard of epoxy putty to form a piston, more like the liquid versions like JB Weld that modelers have good results with. I use an "eyelet" to connect my con rods to the piston. The piston is graphite. Its simplicity does the job and being basicly a woodscrew should thread into the epoxy. You may have to drill a small starter hole and if it threads thru the piston top a dab of regular expoxy seals the hole if you punch thru.

[surgy]

Awesome idea, I ended up modeling a hole for a "main pin" through the side of the piston similar to the way a piston in an ICE works. Oh and I should mention that I have been calling you "Cool copper alchohol burner guy" in my head for weeks now lol, your model engine (on youtube) is what sparked my interest in lamina engines. You have a very cool way of firing your engines with (pipe fittings?) a copper dual burner. Oh and what is this circle on the end of your connecting rod? You know the small dime sized disk on the flywheel side. Is this for a bearing? Also do you mind (or does anyone else mind) to go into detail about a simple and low friction way of connecting the rod to the flywheel? remember I plan on using the platters out of an old hard drive for a fly wheel and the motor as the main bearing. Thanks in advance, I'm really excited now that I have input!!!! << my new favorite hobby!!!

[Longboy]

That "dime" is the rod big end, has a bearing with a brass pin pressed into a corresponding pin hole in the flywheel. Bearings solve rotational friction points. Plumbing parts make good fuel tanks!