I've been having some difficulty with engineering the connecting rods and trying to keep things balanced.
Having designed an LTD style version, to keep the displacers centered and balanced I decided to have one connecting rod slide inside the other. Both would slide through a sleve.
I found copper and brass rods in the hobby section of the local hardware store. Built an engine/heat pump, but the thin soft metal did not have the strength or the rigidity I would have liked. Today I was trying to modify the engine and accidently bent a connecting rod irreparably. It also has the displacer and other parts soldered onto it, so It would be more work than it would be worth to try and fix. So I'm starting over.
I stopped today at the machine shop, told him what I needed, he had tons of stock metal around, but nothing quite right he would have to order pieces from a specialty place, likely mill them down on the lathe then lap them in with grinding compound for a good fit.
He would need exact measurements for what I wanted. I told him I'd try to work out what I needed.
From there I went to Walmart to reload my debit card to pay for my website when I came across what may be the perfect solution.
The machinist estimated the job would cost me around $100. Mostly for the time he felt it would take, and the close tolerances. It would have to be as light as possible, rigid, fit together with as little friction as possible yet be as air tight as possible. A pretty tall order.
Then I found these:
- IMG_20200116_185505597_resize_26.jpg (71.2 KiB) Viewed 8730 times
Need I say more?
- IMG_20200116_185522479_resize_27.jpg (94.46 KiB) Viewed 8730 times
They cost like $3 each.
I really don't think for $100 I could have gotten anything custom made as lightweight, rigid and to such close tolerances.
Each one has more tubes within tubes within tubes within tubes etc. than I actually need. I bought extra anyway.
I suppose an old radio or TV antenna might work, but these, although they look like those old telescoping antennas, seem somewhat sturdier. They are made to extend quite a distance, and feel more rugged than a radio antenna though they look and function similarly.