Mery Explosive Engine - page 4
Here are the eccentric straps. I cut them apart then cut them on the split. I filed the joins a bit to get it close then milled a small flat on the back. It establishes a parallel to the joint. I flip it back over and rest on that flat to cut the joint. Once the joint is cleaned up on both, flip them back over and cut the backs again both at the same time so when the parts are put together, the joint is exactly in the center between the flats. Then I bored the hole on the mill. The green plate on the lathe is a jig to clamp the part to so I could cut the groove inside the bore. It's more reliable than using the mill. The last 2 pics are using an indexing head to locate and drill the oil and rod holes.
For the spark rocker I needed some place to start. I filed the casting numbers down until they were at the same plane as the outboard arms. Then I set it up in the mill eyeballing everything level. This give me a starting point. I milled 3 flats on the shaft for the lathe's 4 jaw chuck. I flipped it over and milled a fourth flat. Size doesn't mean anything it's just flat surfaces to hold. I set it up in the lathe and indicated to the round part. It's a casting so it's not going to be that critical it's a starting point. I then took a skim cut across the arms then faced the inside to length, then drilled and reamed it. Just for kicks I also turned the outside of the arms so they are centered and square. In the 3rd pic I set a parallel on the faced section to square it that way and eyeballed the arms level. This gave me the hold I needed to mill the pads for the 3/16 hole. I also took skim cuts at the ends of the arms to establish the same arms level later. I wasn't sure if I would need it but I'm VERY glad I did. The 4th and 5th pics are having the part clamped using those flats and the face cut I made on the arms when I had it in the lathe. Another example of taking an opportunity to make a location cut any time you can since you never know when you'll need it! The last pic is again using those flats cut earlier to rest it on parallels to cut the recess and drill the holes.
It's been a while since I posted any updates. I spent the past winter doing the finish polishing, plating and painting. I actually ended up painting several parts a few times. I painted the main body and a few other parts with color then clear using Krylon. The clear was so brittle that as soon as I tightened a nut against it, the clear shattered like glass. So I striped and repainted with Rustoleum. That paint is much less brittle. I also plated most of the hardware with nickel plate. I didn't get all of the parts done so I'll have to setup the plating tanks again. The photos here are with a lot of the parts assembled. The picture on the rigth end has the cooling pump. I tried to build a centrifugal pump but to build one to a reasonable scale just didn't work to move water. I resorted to a positive displacement pump instead. It's my own design and hopefully works. It's belt driven by a large O-ring from the main shaft.
I got to a point where I had enough of the engine together that I could see if it will run. I'm using propane for fuel. It's a lot easier to deal with then white gas and a lot less messy. I opted to mount the spark plugs under the explosion chambers instead of on top. The ignition module is from S/S Machine & Engineering. Instead of mechanical points I'm using their hall effect module. The magnets are on the eccentric gear. It didn't take much to get it going. Using the fuel mixer in the plans made the engine run pretty rich until I removed the air screw all together. It ran for a couple minutes until I shut it down to cobble together some cooling lines and get the camera ready. The cooling lines and fittings leak a bit but this was just to try the engine for a few minutes. There's a knock that can be heard while it's running. I don't have the flywheel seated properly because I still haven't finished painting it. Next I'll work on plumbing up the cooling lines. You can see the pump seems to be doing pretty well on this run.