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I'm curious about attaching the piston rods to the slider with a wedge. Seems like the alternating stress that joint receives when the engine is running could easily work the wedge loose. Also, why did they do it that way? It doesn't seem like a joint that would need to be disconnected often during normal maintenance nor something that needs to be easily replaceable.Beautiful work indeed, Chris. Your threads are my first stop whenever I visit the forum. I continue to be amazed at the speed with which you work and the fact that you're doing all this with Sherline equipment.
Have the shop elves been for a ride on the tops of the pistons yet? (or 100 rides?) re wedges - I can say for sure that most if not all full size steam locomotives in North America had the piston rod secured to the crosshead with a tool steel wedge. Some rods had a threaded connection too, but the wedges secured them. Have not heard of any that came out by accident. They usually were fitted at a strategic angle so there would be access such that they could be hammered /drifted in or out, which required BIG hammers or pneumatic impact tools. Very secure fastenings, many tons of force to shift them. Just food for thought.
In locomotive practice, and probably elsewhere,the socket in the crosshead and the end of the piston rod are tapered.Dismantling needs a holder-up kneeling or crouched by the crosshead holding the end of a stout bar against the bottom of the cotter and another bloke in the pit under the engine with a sledgehammer. Watching this on one occasion I caught the cotter as it flew past the holder-up's ear. There was no clang of it landing. From below in gravely Liverpudlian: "Where the f*** did that go?" I was not sufficiently quick witted, and failed to hold it behind my back while staring up at the shed roof.Now the fun begins. At the SVR* we have a tool that fits in the other side of the crosshead after the conrod is removed. It is a while since I last saw it and I don't remember the details. I assume it fits the gudgeon pin hole. A large diameter but fine threaded screw arrangement presses hard aganst the end of the piston rod, while a slide hammer on the outboard end of the tool is used to, eventually, dislodge the taper. At a major overhaul the cotter will often be replaced, and the rounded pressure edges are carefully blued and filed to fit.*https://www.bbc.co.uk/news/uk-england-shropshire-62808569
HiI have word on some stationary and portable full size engines and have seen these wedges often coming loose and had to knock them back in i see holes in the wedge so a wire or a pin can be fitted so they cannot fall completely out may be they are not fitted well enough or not hit in tight enough but it looks like on these engines there is difficulty in keeping them tight.your engines are looking amazing.John