Fixed a waterpump for a late 1800's hot air engine ( R&T )

[JRD77VET]

Rough and Tumble has a late 1800's ( 1875 or later) Erickson Hot Air engine that works on the Sterling principle ( to over simplify, hot and cold air move back and forth to make it work ).

The hot air engine was designed to pump water. At the bottom of the waterpump casting is a rubber "dowel", one inch in diameter that provides a seal when pushing the water out. It "flutters" when water is drawn in.

First picture shows the hot air engine with the waterpump removed. It attaches on the right side and the brass rod on the over arm moves the pump shaft up and down to pump water.

Second pic is info

Third pic is the water pump in operating position showing the corrosion on the bottom.

4th pic shows my setup. I have it sitting on two pieces of 1/4" x 1/2" aluminum flat bar. The 3/8" threaded stud is thru the factory hole that holds the end covers in place. I lucked out as the table on my bench top mill is narrow enough that both flanges cleared the table.

5th pic is the undersize 1" endmill I used to mill the corrosion out. I took about .010 ( ten thousandths) each cut while "drilling" down with the sharp corner of the endmill.

6th pic is where I ended up with clean up.

7th pic is my boring head which just cleared the hold down nut AFTER I turned it a littl etighter to position the flat on the hex

8th is the finished bore / clean up. To measure how wide I was, I would put the cutting edge of the boring bar directly opposite the cut side and measure across with my dial calipers ( and an experienced eye)

9th pic is a piece of 1" round steel bar laying on the machined surface to show the correct radius was machined. A 1" round piece of rubber "dowel" goes in there when it's assemebled. When it draws water in, it will lift to allow it to fill the pump cylinder. When it pumps the water out, the water pressure will push the rubber dowel down.

I was extremely happy to be able to help out at www.roughandtumble.org where I volunteer.

Jeff

[SnikPlosskin]

Just wow. It’s incredible how innovative these old designs are.

[Stevedore]

Very nice work. I'd say that Rough & Tumble is fortunate to have you & your skills available.

[JRD77VET]

Originally Posted by Stevedore

Very nice work. I'd say that Rough & Tumble is fortunate to have you & your skills available.

There is a lot of talented folks at R&T.

But I am glad I can help out at no cost to them.

[WOEII]

Thats awesome. Wanna hear that "flutters".

[BOTY]

Nice.