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1" Bore x 1" Stroke Vertical i.c. Engine

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  • Originally posted by nickel-city-fab View Post

    actually I was thinking of the Desmodronic "spring-less" valve gear, it uses cams to both raise and lower the valves. With *very* small clearances.
    I wonder if anybody has ever done a Desmo system in a scale model before.....off to you tube.....
    Last edited by Dan Dubeau; 02-20-2021, 10:39 PM.

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    • The split-single is different, but, I think the Ducati valve gear takes different to a whole another level.

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      • OK, I'm guilty
        Let's not take Brian's thread off track
        I'll start another thread for the motorcycle-esque continue.

        new motorcycle-esque thread is here:

        ​​​​​​https://bbs.homeshopmachinist.net/fo...-model-engines
        Last edited by Ringo; 02-20-2021, 10:43 PM.

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        • Guilty as charged, so I'm in the other thread too -- trying to keep Brians clean

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          • Aostling--Yes, mom grew up in a very small village. The nearest town, Bancroft was about 10 miles away. She is in a nursing home in Bancroft, which is about 185 Km away from where I live. I drive up to see her once a month.--And I'll be leaving the Desmodronic valves for Ducati.
            Brian Rupnow
            Design engineer
            Barrie, Ontario, Canada

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            • Originally posted by brian Rupnow View Post
              Aostling--Yes, mom grew up in a very small village. The nearest town, Bancroft was about 10 miles away. She is in a nursing home in Bancroft, which is about 185 Km away from where I live. I drive up to see her once a month.--And I'll be leaving the Desmodronic valves for Ducati.
              I'll bet that is why she has lived so long and done so well. Being from a small place way back when. My Grandmother was similar, a farm girl from Michigan in a German settlement. She told stories of how there was no electricity etc and they did everything with horses. And yes, I don't blame you for passing up on the Ducati valve gear.

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              • I'm doing a bit of assembly this morning, and these three shots are interesting. In the bottom of the main bearing cavity in this half of the gearcase, you will see the heads of four #6 flat head capscrews. They pass thru the gearcase and attach a steel ring on the outside of the gearcase. The plate with the handle on it is the plate to which the ignition points are attached. Screwing the handle in locks the points mounting plate in place. Unscrewing the handle half a turn lets me rotate that plate while the engine is running. Since the ignition points are attached to this plate, this lets me advance or retard the ignition timing while the engine is running.


                Brian Rupnow
                Design engineer
                Barrie, Ontario, Canada

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                • A shot of the other half of the gear case shows the oil filler tube pressed and Loctited into place.
                  Brian Rupnow
                  Design engineer
                  Barrie, Ontario, Canada

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                  • Elvis has not left the building---Elvis has struggled all day with cams and tappets. I don't make cams often enough to have all the steps memorized. Basically, that means that every time I make a cam, I have to refer to a bunch of notes I have made and try to decipher what I actually meant when I wrote them. Here we have one cam, setting in place with a mushroom head tappet. Tomorrow I will make the second cam. Piece of cake, now that I have refreshed all my memories by making the first cam.
                    Brian Rupnow
                    Design engineer
                    Barrie, Ontario, Canada

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                    • Sometimes I think cams are the most difficult thing to design. They give me brain cramps, like trying to understand the opposite sex. Here's an entire book on the subject, free download as PDF https://www.google.com/url?sa=t&rct=...fxk77cCXk9Cf9t

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                      • Originally posted by nickel-city-fab View Post
                        ... Here's an entire book on the subject, free download as PDF https://www.google.com/url?sa=t&rct=...fxk77cCXk9Cf9t
                        The book has one chapter on screw machine cams. These are low-speed positional cams for making parts. The high-speed cams in engine valve trains are faced with dynamic forces; the emphasis is on avoiding excessive values of acceleration and jerk.

                        My knowledge of cams is theoretical. Brian has hands-on experience, and that will what saves this nice engine in the end.

                        [edit] I dug into an old box of books, and found my old engineering textbook. It was Shigley's1959 Kinematic Analysis of Mechanism. I have not found that online, but here is a later edition by Shigley which expands on the older material. The cam section starts on p. 193.

                        ftp://117.239.47.98/Mechnical%20Engi...0Mechanism.pdf
                        Last edited by aostling; 02-23-2021, 01:17 AM.
                        Allan Ostling

                        Phoenix, Arizona

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                        • Originally posted by aostling View Post
                          [edit] I dug into an old box of books, and found my old engineering textbook. It was Shigley's1959 Kinematic Analysis of Mechanism. I have not found that online, but here is a later edition by Shigley which expands on the older material. The cam section starts on p. 193.
                          Thanks for the link! The newest books I have with a chapter about engine cams date to the 1920's, and frankly I can't recall which chapter it was. They did illustrate the pros and cons of various follower or tappet mechanisms with some material about avoiding shock or slamming the valves.

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                          • And now we have two finished, hardened, oil quenched cams. That cam nearest the front looks a bit ragged on the edge, but it's not. The macro setting on my camera finds little flaws so small that they can't be seen by the naked eye. I have to go out to the hardware store and look at the paint color chart for Tremclad paint, and then it's almost crankshaft time.
                            Brian Rupnow
                            Design engineer
                            Barrie, Ontario, Canada

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                            • Uh-Oh--Something just happened. I was happily milling away a whole lot of 1144 stress-proof that wasn't going to be part of the crankshaft. Milling machine just stopped---lost all power. First I looked for the ratty little glass fuse that my old mill had, but this mill doesn't seem to have any separate little glass fuse. Next I checked the breaker in my electrical box.---It was okay. I don't know if the motor has a thermal overload cut out or not.---Doesn't have any visible reset button. Well, Poop!!! I didn't feel that much like working anyways, but I have to figure out what is happening with the mill before I can do any more.
                              Brian Rupnow
                              Design engineer
                              Barrie, Ontario, Canada

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                              • May be automatic, if that is the issue. Wait a while, try again.

                                Do you have a voltmeter/multimeter?

                                If so, you may want to check various things inside the machine. First thing I would check is the power switch.

                                With the machine unplugged, and the meter on "ohms", make sure the power switch is off, measure between the power pins on the plug. should be "open". Next switch the switch to "on". There should be a change of resistance to a low value. (value will be lower if the switch works directly 'almost zero ohms', higher if there is a "contactor", as I suspect there is).

                                If no change, then there is likely an "open" somewhere (this is somewhat "known" since it does not work), and you will want to start checking individual items.

                                Access the "on" switch, and see if it changes resistance when switched. There may be several connections, so try different combinations.

                                IF results are confusing (and they probably will be) a pic of the wiring diagram, and of the unit innards, would be in order.

                                I'd suggest a new thread, your choice.
                                2801 3147 6749 8779 4900 4900 4900

                                Keep eye on ball.
                                Hashim Khan


                                It's just a box of rain, I don't know who put it there.

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