advice needed making valve linkage

Aquarius21 · Oct 24, 2011

Hi, I am at the stage where I am pondering how to make the tiny valve linkages
for John-Tom's two cylinder marine rotary valve engine- my first engine.

http://www.john-tom.com/MyPlans/Steam Engines/RotaryValveEngine.pdf

I welcome any advice especially as I consider; a) how do I turn such tiny parts,
b) how do I make the clevis ends and c) if this is going to be a table top
model, must I turn all linkage parts out of steel or may I use brass?
My thanks for all your terrific advice. Quincy, in the still soggy Nova Scotia
after record breaking 4" of rain.

rleete · Oct 24, 2011

Generally, any materials that are at hand will work for Elmer's engines. As to the tiny parts, you may also scale any of Elmer's designs to suit your capabilities and materials.

For the clevis ends, read the text with the plans. He recommends making the parts out of square stock.

nobeard · Oct 27, 2011

think i will watch this thread with interest because i too are half way through building this engine and again it is the first engine i have built . i have got the crank done and in its bearings i swapped the block type cylenders for seperate brass ones stood between 6 brass colums.

portlandron · Oct 27, 2011

You could make them from square stock as already stated or you could make them from round bar stock sized as needed for the rod section and silver solder round stock of the proper size to each end.

AlanHaisley · Oct 27, 2011

how do I turn such tiny parts
how do I make the clevis ends
if this is going to be a table top model, must I turn all linkage parts out of steel or may I use brass?

_________________________________________________

Make the components in three parts. The middle is just a piece of rod.
Make these separate. It's much easier if you have a mill since you can just hold a longer piece while you make flats and holes on it. To start, hold a piece of rod of diameter large enough to make the clevis. End drill it on the lathe to just accept the rod from (i). Now, cut or file the flats, mark for the clevis hole and drill it. Without a mill you will need to do something like hold it crosswise with a 4 jaw chuck and use a tailstock or toolpost held drill to do the crossdrilling.
You can use either or both. Think about how the metal colors contrast. Assuming the parts are done in steel or brass, you should be able to soft solder them so the joins pretty much don't show.

:-[
After looking this over again, I don't think it likely that the linkage pieces can be made in sections and soldered; they are just too small for that where the parts need to join. Try brass and use HSS tools - very sharp. Concentrate on keeping the tool height centered. You might want to leave the pieces overlong so there is stock outboard to take a center. Also, try to work with the tool cutting face at right angles to the spindle so there will be less tendency for the material to push off. Light cuts of only a couple thousandths. Collets are safest for this work since you will be getting the tool pretty close in.

Stock larger than mentioned in the article might help although you will need to spend more passes cutting it down.

Alan

Bernd · Oct 28, 2011

rleete said:
Generally, any materials that are at hand will work for Elmer's engines.

R,

Don't want to hi jack the thread, but that is not a Elmer's engine. That was published in one of those popular mechanix or such publication many, many years ago. My dad built it while at work, again many many years ago.

Bernd

rleete · Oct 28, 2011

Sorry, I saw John-Tom and jumped to a conclusion.

At any rate, my advise still stands. Make it out of anything you can get your hands on. Brass would be my first chioce, because I have a lot of thin rod, and it's pretty when polished up.

advice needed making valve linkage

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