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Philip duclos odds n ends hit and miss engine

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  • Philip duclos odds n ends hit and miss engine

    This morning I'm just setting around messing with Philip Duclos' "Odds N Ends" hit and miss engine. I have his book with the plans in it, but he calls for 32 DP timing gears while I have only 24 DP gear cutters. A little research shows me that a 16 tooth and a 32 tooth 24DP gear should work fine, and doesn't change anything except the vertical position of the cam shaft mounting hole and the rocker arm pivot hole.
    Brian Rupnow

  • #2
    Good Lord,,, i see ANOTHER project is taking shape!!!!!!!!!!!!

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    • #3
      A question for anyone who may have built this engine. Does the piston skirt REALLY stick out .109" beyond the cylinder when the piston is at bottom dead center? This doesn't seem right to me. Be aware that I have changed the left hand end of the sideplates to come out flush with the back side of the cylinder water jacket, but I haven't changed any of the mathematical relationships given in the drawings in Philip Duclos' book.---Brian
      Last edited by brian Rupnow; 03-14-2013, 09:24 AM.
      Brian Rupnow

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      • #4
        I may have answered my own question. I've just watched half a dozen videos on youtube of this engine running, and yes, it does seem that the piston skirt does come out of the cylinder by about .100 at bottom dead center. This seems a bit strange to me, but the engines seem to run fine, so I guess no harm is done by it.
        Brian Rupnow

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        • #5
          Brian,
          I think at least one of my Debolt engines have the piston skirt exposed at BDC, just like your Duclos engine.

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          • #6
            My sattley 1.5hp hit and miss also has the skirt extend past the back of the cylinder.

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            • #7
              Re: timing gears. The DP and tooth count does not matter as long as the ratio is exactly 2:1. You can choose a tooth count that will allow the same center to center shaft distance as on the drawings.
              Hugh

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              • #8
                I built the odds & ends engine many years ago and no longer have it as it was used for partial payment for my Rockwell milling machine.

                I don't recall if the piston skirt was exposed or not, but as others have pointed out, it does on several full size engines. There is also no reason not to shorten the skirt or extend the cylinder provided there is no interference with the connecting rod swing.

                As far as the gears, the build article included making a 16DP fly cutter to cut the gears. There is no harm in changing the gears and position of the cam gear, just make sure you have room for the governor latching mechanism. Once you change one thing, other relationships also change. CAD will be your friend warping it all back in place.
                Jim H.

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                • #9
                  You may well be right. On the engine plans it calls for a 20 tooth and a 40 tooth set of 32DP gears. The center to center is given as .9375". I picked a set of 16 tooth and 32 tooth DP gears, and they have a center distance of 1". A 15 tooth and 30 tooth set of 24DP gears has a center distance of .9375". The only issue is that a 15 tooth 24DP gear doesn't allow me to have a hub with an o.d. large enough to have 3/8" bore and a keyway and a set screw. Thats why I went "up" one size.
                  Brian Rupnow

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                  • #10
                    Originally posted by JCHannum View Post
                    I built the odds & ends engine many years ago and no longer have it as it was used for partial payment for my Rockwell milling machine.

                    I don't recall if the piston skirt was exposed or not, but as others have pointed out, it does on several full size engines. There is also no reason not to shorten the skirt or extend the cylinder provided there is no interference with the connecting rod swing.

                    As far as the gears, the build article included making a 16DP fly cutter to cut the gears. There is no harm in changing the gears and position of the cam gear, just make sure you have room for the governor latching mechanism. Once you change one thing, other relationships also change. CAD will be your friend warping it all back in place.
                    Jim---Thats why I modelled it in CAD. I wanted to make sure that the larger gear size and center distance didn't hit the baseplate. There is some free spur gear software that lets you plug in the parameters for your choice of gear and it will let you download a 3D cad file. Thats what is shown on the model and the drawing. ----16 and 32 tooth 24DP gears.---Brian
                    Brian Rupnow

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                    • #11
                      I was mistaken. The small gear doesn't need a keyway and setscrew. It gets pinned to the shaft with a 1/16" dowel. That means I can use a 15 and 30 tooth gear with 24 DP and still keep the 0.9375" vertical centers. I have learned something new. I didn't know that gearsets with different diametral pitches can still be configured for the same ratio and center distance. I don't know if thats true in all cases or if I just got lucky here.---Brian
                      Brian Rupnow

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                      • #12
                        I haven't cut any gears since I built my Steam Donky Winch over a year ago. I just got out all my paperwork and my gear cutters out for a full review. I found a few bits and bobs of brass in my brass drawer and came up with enough material to make two gears and the cam. In the original plans, the cam is machined right on the face of the larger 30 tooth gear, however I will have to solder the cam to the large gear. Here is a picture of the bits of brass I came up with, and the calculations I just made to set up my mill and rotary table, and to turn the blanks in preperation for cutting the gears. If anyone has questions, go ahead and ask.
                        Last edited by brian Rupnow; 07-10-2013, 11:52 AM.
                        Brian Rupnow

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                        • #13
                          I for sure would not be that concerned about the skirt popping out that little at BDC, there's so many factors for it being a non-issue, for one it is the most relaxed part of the stroke - no compression and no combustion, two is the piston is at it's slowest speed and three it's also in a position of near dead alignment so the skirt is not really getting loaded much,

                          skirts drag pretty heavy close to half way down the bore due to max piston speeds and misalignment with the crank throws and under loads from compression and esp. combustion...

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                          • #14
                            This first picture shows the two gear blanks turned to the correct outer diameter and thickness. To do this I first drilled and reamed the center holes by mounting the pieces in my lathes 3 jaw chuck and using drills and reamers mounted in the tailstock chuck to get the 3/8" center holes in them. I then Loctited them onto short lengths of 3/8" cold rolled shaft so I could hold the cold rolled in my lathe chuck and finish the o.d. and thickness of the parts. The 3/8" bore will be the finished bore in the small gear. The large gear will get the cam and a 3/8" diameter piece of brass silver soldered to it for "further processing".
                            Last edited by brian Rupnow; 01-20-2013, 03:29 PM.
                            Brian Rupnow

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                            • #15
                              This is the large gear blank with the cam and a piece of 7/16" hex brass turned to 3/8" and all silver soldered together. Messy looking brute isn't it!!!
                              Brian Rupnow

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