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  • Originally posted by brian Rupnow View Post
    Okay, it's time to ask for an opinion. I am going to require a total of four eccentric strap assemblies. Two with straight rods connecting the ends and two on which the rods have a 1/4" offset. In the normal course of affairs, I would thread everything and screw all the pieces together. Although they look huge in this picture, they are only 1.646" center to center. I have a fixture to mount everything on at the exact centers required, and it is imperative that all four center to center distances are exactly the same. I'm thinking to myself "Why not set them up one at a time in the fixture and silver solder the rods to both ends?" The only adjustable thread required would be on the rod which passes thru the valve nut, to center the valve for timing the engine correctly, and the rotational position of the eccentrics on the crankshaft. Opinions please.---Brian
    First thing I would consider is soft soldering. The parts are all brass?
    Or, practice your silver soldering on some other parts.

    Comment


    • Every reversing engine needs a reverse handle, and now mine has one!!
      Brian Rupnow
      Design engineer
      Barrie, Ontario, Canada

      Comment


      • Damned Sweet. Love it!! (Highways being shut down here, big temp drops comming! Lol)

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        • Hi Sasquatch--It's nasty here tonight too. Cold, wet, about an inch of snow. Weatherman is calling for possibility of 6" of lake effect snow. Good night to stay in and set by the fire.---Brian
          Brian Rupnow
          Design engineer
          Barrie, Ontario, Canada

          Comment


          • Nice handle! Most would just polish the end but, no, you go and knurl it! Great touch.

            Pete
            1973 SB 10K .
            BenchMaster mill.

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            • I am getting to the point where all the major links and levers for the reversing system are finished. I have a few itsy bitsy pieces to make and then I'm ready to try this reverse business out. All of the blue parts in the model are finished.

              Brian Rupnow
              Design engineer
              Barrie, Ontario, Canada

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              • I've just had one of those days where it seems I worked awfully hard for minimal results. Most days I go like a whirling dervish and at the end of the day I have a collection of parts to show what I've been doing. Today I made three parts and figured out how to make the final three. I really hope this reversing mechanism works. It is very interesting and there seems to be a lot of small parts involved. I should know in the next two or three days.
                Brian Rupnow
                Design engineer
                Barrie, Ontario, Canada

                Comment


                • This quest for a reversing engine is taking me in some strange directions. I finally have all of the pieces made, tomorrow I will silver solder up the eccentric strap sub assemblies. In the picture you will see a couple of 1/8" shafts with hex nuts soldered to the ends of them. They are destined to be sawn in half and then threaded on the cut ends to yield four hex bolts.
                  Brian Rupnow
                  Design engineer
                  Barrie, Ontario, Canada

                  Comment


                  • I have the first eccentric sub assembly fixtured and ready for silver soldering in the morning. I drilled the center out of the 5/8" fixture rod, leaving only a 1/32" wall so that it doesn't act as a big heat sink. There is a very slight air gap between the eccentric strap and the aluminum fixture plate, probably only about .005", but that will stop a lot of heat from being sucked out of the brass strap end as I solder it. The 1/8" pin which locates the small brass end can be pressed out from the far side if I need to in order to remove the sub assembly from the fixture. I have to do two sub assemblies like this and two with a .25" offset bent into the 1/8" rod. I'll let you know how I made out in the morning.
                    Brian Rupnow
                    Design engineer
                    Barrie, Ontario, Canada

                    Comment


                    • I'm very pleased with how the silver soldering went on my four eccentric strap sub assemblies. I got good flow all around the 1/8" rod at both ends, and good fusion between the steel rods and the brass ends. My "soldering fixture" worked like a charm. I have set one of the assemblies with an offset end up in the fixture for one shot, so you can see the spacer underneath the large end of the strap. I had no problem removing them from the fixture. A two hour soak in Citric acid and then some brisk scrubbing with my small brass bristled brush yields some very nice looking parts---and they are all exactly the same center to center distance.

                      Brian Rupnow
                      Design engineer
                      Barrie, Ontario, Canada

                      Comment


                      • Nice work. That's going to be a good looking engine.
                        Jim

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                        • Up until this point, I have been reasonably sure of what I was doing---as in "Okay, I've done all of this stuff before, so I'm not covering new ground here." Now I have arrived at something totally new, the timing of the two cams at each side of the engine, in relationship to each other. The solid model I have shows a separation of 120 degrees between the high point of the lobes on the two adjacent cams. The part which I have been referring to as the "reversing plate" has a total included angle of about 30 degrees. I have absolutely no idea as to whether this is correct or not. Whoever has created the 3D model I have worked from has done a sensational job, and I can proceed based on blind trust that he has modelled this relationship correctly, but I would really like to have a better understanding of how or why this works. If anyone out there can shed some light on this, I would really appreciate it.---Brian
                          Brian Rupnow
                          Design engineer
                          Barrie, Ontario, Canada

                          Comment


                          • Originally posted by brian Rupnow View Post
                            ... Now I have arrived at something totally new, the timing of the two cams at each side of the engine, in relationship to each other.
                            I think those are more properly called eccentrics. This article refers to them as "eccentric sheaves," a term I have not heard of. https://en.wikipedia.org/wiki/Eccentric_(mechanism)

                            I have my father's engineering textbook from the 1930s -- on reciprocating steam engines. Your splendid engine has inspired me to open its pages for the first time in ages.
                            Allan Ostling

                            Phoenix, Arizona

                            Comment


                            • Originally posted by aostling View Post
                              I have my father's engineering textbook from the 1930s -- on reciprocating steam engines. Your splendid engine has inspired me to open its pages for the first time in ages.
                              The book is Steam Engine Theory & Practice (1934 edition), by William Ripper. Chapter IV is all about the slide valve, and the eccentric which effects the valve operation and timing. There is a simmple formula for determining the eccentric "lead angle," which depends on "lap," "lead," and radius of the eccentric.

                              I'm probably more confused about this than you are. Let's hope your plans are correct!
                              Allan Ostling

                              Phoenix, Arizona

                              Comment


                              • The valves will need some means for adjusting.

                                The basic adjustment is the eccentric position, of course. But the slide valve also needs to have the rod length set to place the center of the movement correctly in relation to the valve openings. That is part of setting the "lap" and so forth.

                                Some of the details are needed mostly to get the best power out of the engine, which you may not need to do. There is a larger range over which it will "run".

                                Since we have seen it running on air, the basics should be covered already.
                                1601

                                Keep eye on ball.
                                Hashim Khan

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