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A new engine for fall---

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  • I have had a crazy busy week, and haven't had a chance to play machinist very much. I did come home last night from the factory where I've been consulting for a couple of weeks, and got a good start on the tappets. I figure that if I have to set the rotary table up on the mill to do the cam anyways, I might as well cut the hex shapes on the tappets, which are being made from 1/2" 01 drill-rod. I hope to get the cams done this weekend as well. You are probably right about the shape of the cams not being all that critical. They are very "not critical" if using a follower wheel on the tappet, but for a flat bottomed tappet, if you don't get the curve right on the cam flank, they will 'slap' the bottom of the tappet on every revolution.----At least that's what the books say.-----Brian
    Brian Rupnow
    Design engineer
    Barrie, Ontario, Canada

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    • This morning I made the tappets from drill rod, which is a "water hardening steel". The machining went reasonably well, until I realized that I had tapped the wrong end of the larger diameter which rides on the cam!!! After remaking the large ends and getting it right the second time around, I carefully fit everything, then took the pieces out to my big garage for hardening. I heated the pieces one at a time with my oxy acetylene torch until they were bright orange, then tipped them into a can of water. I hoped that I wouldn't get much heat distortion which would have buggered up either the internal or external threads, but I must have lived right this week, because everything went back together fine. The outer diameter of one of the large parts may have grown a little, as it was a tight fit into the bronze guide block and I had to set it up in the lathe and polish it a tiny bit with some 280 grit paper. I decided at the last moment to use mild steel #10-24 locknuts, because it was less work, and I figured when used as a jam nut the mild steel would grip better and not back off while the engine was running. In the picture, one valve is open and one is closed, but the cams are still not made. That will be tomorrows job. The blob of stuff on top of the left hand tappet is some oil I had used when assembling things and then forgot to wipe off before taking the picture.

      Last edited by brian Rupnow; 10-04-2014, 02:11 PM.
      Brian Rupnow
      Design engineer
      Barrie, Ontario, Canada

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      • We have a cam!!! Actually, we have two cams, once I get them parted off. Everything went very well, and the profile looks perfect. I took a cut every two degrees of rotation in the rotary table. This leaves only microscopic ridging, which will clean up very easily with a fine diamond file. However, no matter how you do the math, that is 180 trips back and forth with the manual table. My right shoulder will be sore tomorrow from crank turning. Old dogs do learn new tricks---this time after the profile was cut, I left the cam in the rotary table set-up and continued taking cuts every two degrees until I had completed the full 360 degrees. This is an excellent method of making cams, but it is tedious. Tomorrow I will dress things a bit with the fine diamond file and part the cams of from the parent stock. Then they will be flame hardened and quenched, then silver soldered to their individual camshafts.

        Brian Rupnow
        Design engineer
        Barrie, Ontario, Canada

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        • Those really look good Brian! I bet they work fine.
          Kansas City area

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          • Okay--Experiment completed. I had a bit of left over 1/2" drill rod. It cuts very easily with a file. I flame hardened and quenched one end, put it in the lathe to hold it, and tried to cut it with a file. Couldn't cut it at all. Harder than the devil's horn!!! I set it up in a vice and silver soldered a small bit of 3/16 mild steel shaft to the end of it, let it air cool, and again set it up in the lathe. The file now once again cuts the drill rod very easily. The heat of silver soldering "unhardens" the hardened drill rod. ---Something worth remembering!!!


            Brian Rupnow
            Design engineer
            Barrie, Ontario, Canada

            Comment


            • Hi Brian,
              Just a question(s)... Was there an effort to solder the 3/16" mild steel concentric to the 1/2" drill rod? Or at this time is it just an experiment to observe the metal hardness?
              John M...your (un)usual basement dweller

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              • No effort whatsoever DejaVu--It was just set on there for the experiment.
                Brian Rupnow
                Design engineer
                Barrie, Ontario, Canada

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                • AAARRRRGGHHHHH!!!!!!!!!!---Giant headslap for me!!! I cross drilled the cams, hardened the cams, cross drilled the cold rolled camshafts, made up .093" cold rolled cross pins----and trial fitted everything. Was being REALLY careful with the cams. Slathered everything with Loctite, dropped the cam into place, aligned the cross drilled holes, and as I pushed the .093 pin into place by hand, encountered some resistance. Took it out to the anvil and CAREFULLY tapped the pin all the way thru.--And then---just as I thought I had won---I heard a little "crack"!!! OH POOP!!!!!
                  Brian Rupnow
                  Design engineer
                  Barrie, Ontario, Canada

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                  • They were supposed to BOTH look like the one on the left----Honest!!! The cross pin is mild steel and will get filed down until the surface is an exact match for the hardened cam surface. And everything is coated with #638 Loctite.
                    Brian Rupnow
                    Design engineer
                    Barrie, Ontario, Canada

                    Comment


                    • I have been so overwhelmed with "busy" in the rest of my life, that I haven't had time to devote to this engine lately. I did manage to steal two hours yesterday evening to remake and harden the cam which was broken and assemble the cams, camshaft, gears, and tappets and tappet guide. This engine is getting very close to being a runner. During the rush leading up to having the top end of the engine finished, I forgot to lap the valves into their seats. Fortunately, I can easily access the valve stems to grip them with a finger chuck when the cylinder is removed from the engine, so that shouldn't be a problem. I am very pleased at how well the gear/cam/tappet train seems to work, so have attached a short video of them in operation.
                      https://www.youtube.com/watch?v=ZIe3...ature=youtu.be
                      Last edited by brian Rupnow; 10-10-2014, 09:24 AM.
                      Brian Rupnow
                      Design engineer
                      Barrie, Ontario, Canada

                      Comment


                      • Looks good Brian! A little tight on the tappets is probably better than to sloppy.
                        Andy

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                        • I haven't abandoned ship--Just been very busy. This afternoon I made up the knurled adjuster knobs that fit on the ends of the camshafts, but then found out I was out of #8 socket head capscrews of the correct length. I stuck two in the place that the much shorter ones will go in when I get them. On the right you can see the true meaning of "Make it up as you go." I forgot to lap the valves, and cut the long piece of parent metal off that I generally use for a handle when lapping the valves and seats together. So---I made up a pair of extended 1/4" "handles", counterbored them 1/8" to suit the valve stems, and cross drilled them together with a 1mm (.039") drill for a drive pin to connect them. The valves needed to be cross drilled anyways, so it kills two birds with one stone. I will lap the valves tomorrow and start the final assembly of everything.
                          Brian Rupnow
                          Design engineer
                          Barrie, Ontario, Canada

                          Comment


                          • This morning I got up early and lapped both of the valves into the seats. I first lapped them with 400 grit carborundum paste, then after a good cleaning, lapped them again with 600 grit. Everybody seems to do this a different way. In an earlier post you will see the "handles" that I attached to the valve stems. (Normally I leave the parent material from which the valves are cut long enough to be a "handle" and then cut it off after lapping is completed). The valve seat and valve face are coated with the carborundum paste (it doesn't take very much) and then the "handle" is gripped between my thumb and finger and revolved back and forth while pulling the valve into the seat. I do this ten times back and forth, then lift the valve off the seat,rotate it a quarter turn, and then repeat. I do this a total of ten times. Never use a power tool to do this. This is a job for "finger twiddling" only. After a thorough cleaning of both valves and seat areas, the valve springs and brass keepers were installed and the .039" cross pins installed. This as a job that always makes me wish for a third arm and hand, but I manage with the two I have. I am now at the point where I can't really go any further until I can buy a tube of Molycote grease tomorrow for the big end needle bearing. (Do you suppose turkey grease would work?--It's thanksgiving here today.) The valves open and close very nicely, which is always pleasing to see. I hear my wife up now preparing a feast for hoards of children and grand children, so being a firm believer in self preservation I had better get upstairs out of my machine shop and help her.--All you other Canadians following this thread---Happy Thanksgiving!!!---Brian
                            Brian Rupnow
                            Design engineer
                            Barrie, Ontario, Canada

                            Comment


                            • Hi Brian,
                              Looking good.
                              Happy thanksgiving.
                              Enjoy the Turkey.
                              Dave

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                              • Happy Thanksgiving Brian & Family
                                I am about to migrate from the computer to the kitchen for a couple of chores
                                We have a daughter coming today and apparently he is bringing an ailing coffee maker.
                                So I will get to spend some time in the workshop today, but not working on my projects.
                                Larry - west coast of Canada

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