All Glass LTD?

[theropod2]

I was day dreaming at my work today about building a LTD Stirling from almost entirely glass parts. This would require either welding borosillicate (pyrex) or using adhesives capable of withstanding the stresses.

The displacer might be blown from one piece or molded. The displacer gland/rod, and the power piston/cylinder, could be machined via precision grinding.

I think such an engine would be exquisite, if not a delicate bitch.

What do you all think?
R

[fullofhotair]

I think it would be beautiful. what if the displacer was made of aerogel. Its called frozen smoke and weighs almost nothing.A cloud in glass.

[Ian S C]

Should be possble, there was a completely glass built steam engine on the web a year or so ago, boiler, cylinder, piston ,crankshaft, flywheel, and it worked. Ian S C

[vamoose]

Theropod2,

I can see strait through your idea!! ;D

Or at least, i hope to in the future...

vamoose

[theropod2]

I have been considering the thermal qualities of glass and I'm worried that the ability to reject heat will be an issue. I'm worried that the heat will creep throughout the engine without some way to rid the engine of that heat. What I mean is the glass isn't good at accepting or getting rid of heat. Maybe copper plates on each end, and everything else glass?

R

[theropod2]

After looking into the various types of glass I've hit a wall. Borosillicate (Pyrex) glass requires a oxygen/gas flame whereas flint glass will melt in a propane torch flame. Boro is much stronger. Not sure if I wanna invest the money in a oxy torch and learn to flame work glass that bad. Hmmmm.

Just wanted to update this thread after the attack.

R

[Chriske]

theropod2,

You could use a alcohol flame. It's rather hot(enough) and will not melt the Duran or Pyrex displacer cylinder.
A gas torch will not work because it will melt the glass, or at least the gas flame will deform the glass part as in one of my tests a while ago using a Duran displacer cylinder in one of my engines.

Problem with any kind of glass will be the expansion phase during heating. While expanding during heating different glass parts should not touch each other. If they do it will shatter. Second problem will be assembling the parts together. Bolting is out of the question because again due to the strain this time glass will shatter. At some point you could use glue to assemble the parts but I do not know of any kind of glue withstanding this kind of heat.

Anyway there is a way to deal with it. I always use rubber O-rings to lock the glass cylinder in it's aluminum holder. But as you were planning to make an all-glass engine that would be out of the question I suppose..?

Ian,
were did you see that all-glass steam engine, I surely like to see that one running just to understand it's secret...

Thanks

Chris

[theropod2]

Chris,

I'm trying to build an LTD (or pretty low TD) engine, so the running heat source isn't the issue here. I'm talking about making the little glass parts and which glass to use. Flint glass can be worked with a propane handi-torch, whereas it takes the oxy-gas torch to flame work Pyrex. I know I can't mix the two as they have different expansion rates, and there may be enough heat difference to make that a problem.

As for mating the hot end/cool end to the displacer chamber I'm thinking clear silicone sealer if I end up using metal for those parts. I may be able to make such an engine run with glass ends, and Pyrex plate is available. Maybe only the cool end needs to be metal? Welding two hunks of Pyrex isn't that tough. I've done that back when I took chemistry in college.

Pyrex, borosilicate, is very durable and much tougher than Flint, and should make a better engine. Enough of a difference?

I'm looking for some glass on glass syringes for the power piston and displacer gland. I may have to use Airpot sets for that, and live with the graphite pistons. I can't quite figure out how to form a ultra-thin and ultra light glass displacer, but I do have some very large metal halide bulbs that are made from Pyrex, and they are already pretty thin and about the right diameter in their middle. I may experiment with one of those. I know, let off the vacuum first!

I need to make some of the glass parts so they can be taken apart. Mechanical fittings. I'm wondering if I can make threads in and on connecting rods and their end caps by using steel screws as forms? Maybe I could make the hot-end cool-end stand-offs out of tubing with threads formed on the inside. How cool would glass screws be?

I'm thinking I may bite the bullet and buy a small oxy-gas setup, a variety pack of Pyrex rod and tube, and see how many times I can burn myself.



Anyway, I'm actually looking at building a prototype, an as I proceed I'll document things here.

R

[Chriske]

Thanks,

it's all very 'clear' now...

Chris

[aero]

Rather than screwing around with cutting jars, Corning made Pyrex glass coffee percolators in various cup sizes and one of the parts was a glass cylinder that of course is being trade marked Pyrex heat treated. Best pace to find these is a hardware store that has been around a long time. The ones I bought were priced at $.89.

[Ian S C]

To stick it together, there is a glue for building aquariums, it sets with UV light, just sit it in the sun is OK, its got to be strong, thik of the weight of water, 10lb per imp gal, or 62.43 lb per cu ft. Ian S C