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Thumper---A new 1 3/8" bore i.c. engine

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  • #46
    This pretty much covers the work that can be done with the two plates still bolted together. The exterior profile is completely machined, and a good portion of the inner profile. And it comes close to my own limits for the day. Tomorrow I will separate the plates and mill away what is left of the inner profile, and add some counterbores and some tapped holes.
    Brian Rupnow
    Design engineer
    Barrie, Ontario, Canada

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    • #47
      Today seen the completion of the side plates and first assembly of the overall frame. Everything goes together and everything clears. I will now order my piston rings. I don't want to make the piston until I have the rings and I don't want to make the cylinder until I have the piston. While I wait for the rings I will make the next part which sets on top, where the bearing caps would usually go.
      Brian Rupnow
      Design engineer
      Barrie, Ontario, Canada

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      • #48
        I guess the 1 3/8 bore should have given me a clue as to the size but the pictures of the side plates here really do set the scale of the final size. It looks like it'll be a bigger overall engine than a lot of your other ones.
        Chilliwack BC, Canada

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        • #49
          BCRider---See post #1 for overall size.
          Brian Rupnow
          Design engineer
          Barrie, Ontario, Canada

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          • #50
            I know, but measurements just don't hit the senses the same as seeing the parts actually done.
            Chilliwack BC, Canada

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            • #51
              The next part that sets where the bearing caps would normally go is going to make my old heart go Pitter-Patter!! It is going to be a cam box, which has the camshaft bearings, camshaft and cams in it. The bolts which thread into the rest of the frame on each side of the main bearings pass thru this in clearance holes. The "window" cut into the side allows me access to the cams to set them at the proper rotational aspect.
              Brian Rupnow
              Design engineer
              Barrie, Ontario, Canada

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              • #52
                Originally posted by BCRider View Post
                I guess the 1 3/8 bore should have given me a clue as to the size but the pictures of the side plates here really do set the scale of the final size. It looks like it'll be a bigger overall engine than a lot of your other ones.
                Brian is not sparing the beef, this time.
                25 miles north of Buffalo NY, USA

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                • #53
                  Today I machined the cam box. It is finished except for the bores for the camshaft and bearings and the recess and clearance for the crankshaft bearings. I'm not sure if I can get #10 bolts that are long enough, but if I can't, then studs and nuts will work.
                  Brian Rupnow
                  Design engineer
                  Barrie, Ontario, Canada

                  Comment


                  • #54
                    GEEZ,
                    Brian has a self-contained cnc going on inside his head.
                    Is anybody here a cartoon or caricature artist?
                    Some body should make a sketch of Brian holding a rs-232 cable between tongue and thumb and the mill is just spitting out the parts !!!!!

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                    • #55
                      Well I have some 10x24 that are 4" long, but they're hardware grade. Slotted heads. You should be able to get up to 6" socket head. Good luck getting less than 100........
                      I cut it off twice; it's still too short
                      Oregon, USA

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                      • #56
                        I was able to buy #10-24 shcs x 3" long today, and shortened them to 2 3/8". They worked fine and had enough thread that I didn't need to extend the thread with my #10-24 die. I've had some other stuff going on today, so didn't get any real machining time in on my project. Tomorrow I will set everything up on my milling machine and drill/bore the clearance for the crankshaft and the recessed bore for the crankshaft bearings, as well as the bores for the camshaft and bearings.
                        Brian Rupnow
                        Design engineer
                        Barrie, Ontario, Canada

                        Comment


                        • #57
                          This morning was time to bore the cam box. I have learned thru experience, that this should be done with the cam box attached to the engine. First step was to attach the entire engine to an angle plate, set up square to the mill bed. The cam box was removed, and the bearing which sets in the sideplate recess was loctited to a piece of 1/2" shaft and held in the mill chuck. This allowed me to move the mill bed in both the x and y axis until the bearing was an exact fit into the recess cut for it. the DRO was set to "0" and the cam box was securely bolted in place. That allowed me to put in both the clearance hole for the crankshaft and the bore in the exact place it should be. Then it was time to move the mill table the required amount to put in the clearance hole in the cam box for the camshaft and cam bearing. I will now flip the engine over and repeat for the far side holes. I had to use a boring head to prepare the recess for the crankshaft. I got lucky and had an endmill of the exact size I needed for the camshaft bearing recess.
                          [img]]https://imagizer.imageshack.com/img923/3056/MjFE9U.jpg[/img]

                          Last edited by brian Rupnow; 03-10-2020, 10:37 AM.
                          Brian Rupnow
                          Design engineer
                          Barrie, Ontario, Canada

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                          • #58
                            And here we are with all of the ball bearings and dummy shafts in place.
                            Brian Rupnow
                            Design engineer
                            Barrie, Ontario, Canada

                            Comment


                            • #59
                              I can't reach Dave Reed at Ringspacers.com. I have emailed him and tried to telephone him, but nada. I want to buy a set of two rings for this engine I'm building but I can't reach Dave, who I've dealt with before. Are there any other reputable dealers that sell 1 3/8" dia x 3/32" thick piston rings for a 4 cycle i.c. engine?---Brian
                              Brian Rupnow
                              Design engineer
                              Barrie, Ontario, Canada

                              Comment


                              • #60
                                Regardless of whether I go with 1 3/8" bore or have to change over to a metric semi equivalent 35 mm (in order to get rings), the gears won't change. I have the material on hand to make the small gear from mild steel, and the large gear from cast iron. I would rather make the large gear from brass, but it's gotten too spendy $$$ for my blood.
                                Brian Rupnow
                                Design engineer
                                Barrie, Ontario, Canada

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