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Tandem Compound Poppet Valve Steam Engine Build, ala Cedge

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Bernd: Beautiful work as always Steve.  :jaw:   :thumbup: Picked up on the aligment tool. Neat. Will have to remember that. Bernd

cedge: Bernd... Thanks for the encouragment. That little wheel is worth several times its own weight in chocolate....LOL.  It hates wobble. When I remount a work piece in the chuck, it often wobbles when the lathe starts up. By running the wheel up against the work piece, it nudges it back into axial alignment. You can nudge form the side or it can do its job by running against the end of the work piece. Very handy. In the sad saga of the Cam Gear disaster in the Victorian build, I managed to nearly destroy a gear that had many hours of work in it. A stupid mistake on my part had the gear twisted to about a 20° angle to its axis. After the dust settled and my heart began beating again, the wheel tool was applied to remove the damage. I ran the wheel against the "end" of the piece to get it turning straight, then I nudged the rim back into concentricity from the side. This wheel tool is made of a simple round on a shaft. My next one will probably be made with a bearing. Steve

Brass_Machine: Nice work Steve. I read the post from back to front... was looking at the port hole asking myself how you did it. Glad I got my answer. Nice job! Eric

Rob.Wilson:  :bugeye: :jaw: :jaw: :jaw: :jaw: WOW  very nice Steve  :bow: :bow: :bow: Rob

cedge: Tonight is going to be a bit photo heavy, so bear with me. These engines have a longer than usual cross head guides. Each of them will have long openings , similar to the one I put in the spacer section. Building them has proven to be a bit frustrating as I managed to make the same mistake, not once, but twice, resulting in the openings being rotated about 8.5 degrees off plumb. That is what happens when you are using hex bar and forget which face you used to index in the vise... nuff said.....@#$&%*!! Simple solution.... use round stock with one flat spot....LOL. The first successful cross head guide is shown below, after it was turned, faced and then milled. The opening was drilled and milled to 9/16 just as the spacer was made. The elongated part of the cut was done using an end mill in small steps that were milled through, top to bottom in small bites. This procedure will be shown, in a few moments. Once things were deburred and some file work was completed, a pair of small 9/16 rounds were turned and drilled with a 3/16 hole. The reason for the hole is for an easy alignment later in the process. The rounds were left slightly over sized, perhaps .002 so they would fit snuggly in their respective radii. The space between them now needed to be filled, but the piece had to fit around the rounds snuggly.as well. This was accomplished by carefully milling a piece of 3/4 square stock 9/32 deep with a 9/16 end mill and then using it to bore through the square for the other arc. The piece was then milled down to fit the gap. Once this were fitted properly, a session of soldering was next on the agenda. I even took time to use a pencil lead around the areas where I didn't want solder to puddle and stick. Solder won't adhere to pencil or even smoked metal, making for less clean up. The work piece was left to cool and then moved back to the lathe to turn down the new metal. This also let me inspect the solder joints which proved to need a little additional work. Once a couple of solderless joints were addressed, it was time to see how the windows were going to turn out. This is the step where those two 3/16 holes in the end pieces proved their worth. By putting a 3/16 dowel pin in the chuck, I was able to easily center on the holes and align everything for the next step. Note the pencil lead can still be seen in this photo. After centering the quill with the dowel pin, the next step was to bore a couple of 7/16 holes to begin opening up the window ports. Then the end mill was used to "nibble" out the remaining metal a bit a time. Run it all the way through and then advance it a few thousandths until you remove the unwanted metal. Then you want to make a quick pass back along the opening to clean things up. Once the milling operation was finished, it was back to the lathe to  make the bore round once more. First step was to use the half inch end mill to get everything back to the original bore dimension. I then widened the first 1/2 inch using a boring bar until the 9/16 end mill would just barely sip into the opening. It's no fun trying to use a boring bar in an interrupted cut. Just trust me on this...(grin). The missed alignment of the port wasn't the only headache this adventure produced. The end mill made a nice substitute and soon had the bore where it needed to be. There is still a bit to do to the piece, like adding a pair of ribs which will need to be soldered in place, but the next one should be a breeze after feeling my way through this one. The little single cylinder has become somewhat of a test bed as I work through the ins and outs of some of the parts. I only hope it won't suffer from all the abuse, when things are completed. Steve

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