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  • Brian builds an Atkinson Engine

    Today I received a complete set of drawings to build an Atkinson 4 cycle engine from Jan Ridders, in the Netherlands. Jan sells these plans for a very reasonable "donation" of 5 to 10 Euros (About $6 to $12 Canadian.) I have looked through the plans, and they seem very complete and well documented. Also included with the engine plans is a set of plans for an atmospheric carburetor. The plans are in metric, so I will model them all in Solidworks as metric parts and then use some of the computer magic inherent in Solidworks to print out drawings with the dimensions in British Imperial (Which I am far more comfortable with when working in my machine shop). I will be changing fastener sizes and shaft sizes to Imperial as I do up the models. I will post the 3D models along with step by step pics of the actual build procedures as I go along, however I will not be posting detail drawings, as that would be very unfair to Jan. This is a rather amazing engine, as it accomplishes all four cycles--Intake, compression, power, and exhaust with one revolution of the crankshaft!!! This will be my third I.C. engine. as I have previously built the Kerzel hit and miss engine and everyones favourite, the Webster. Follow along---This probably won't be a quick build, but it should be a fun build.----Brian
    Last edited by brian Rupnow; 07-27-2012, 04:26 PM.
    Brian Rupnow
    Design engineer
    Barrie, Ontario, Canada

  • #2
    Well, here's a beginning. The first thing I notice is that Jan used a 24mm bore, and I only have a 7/8" (22.22mm) reamer. Since I have more faith in my ability to get a good consistent reamed finish than a good consistent bored finish, I THINK I will design this with a 7/8" bore. Jan calls up grey pearlitic cast iron for the cylinder, and since I haven't worked with that before, I may try and use it, depending on cost.
    Last edited by brian Rupnow; 07-27-2012, 04:30 PM.
    Brian Rupnow
    Design engineer
    Barrie, Ontario, Canada

    Comment


    • #3
      As I get a bit deeper into this, I see that his engine is designed with valve cages, rather than having the valve seats directly into the cylinder head. For my opinion, thats a GOOD thing. I also note with some interest that he doesn't show any piston rings. I may add a Viton o-ring, I'm not sure yet.
      Last edited by brian Rupnow; 07-27-2012, 04:30 PM.
      Brian Rupnow
      Design engineer
      Barrie, Ontario, Canada

      Comment


      • #4
        Well There!!! Thats enough modelling for one day (As if I didn't get enough of this through the week!!!!) This is a very interesting engine.
        Last edited by brian Rupnow; 07-27-2012, 04:31 PM.
        Brian Rupnow
        Design engineer
        Barrie, Ontario, Canada

        Comment


        • #5
          Here we have it guys. About 8 to 10 hours modelling yeilds this. My software tells me that there are a total of 65 parts, not counting fasteners, of course. The sparkplug is not modelled and the pushrod which either presses on a piezzo electric crystal or opens a set of ignition points is not yet modelled either.
          Last edited by brian Rupnow; 07-27-2012, 04:31 PM.
          Brian Rupnow
          Design engineer
          Barrie, Ontario, Canada

          Comment


          • #6
            I bought some grey cast iron today from Barrie Welding here in town. They weren't sure about the "pearlitic" but they said that this cast iron material is what local engine rebuilders make cylinder liners from, and small custom cylinders. It is very fine grained with no voids, cuts extremely well, and is self lubricating. I bought a 5" length of 2 1/2" dia. and a 3" length of 1 1/2" dia. for ten dollars total. The material I bought comes in round bars of varying diameters.----Brian
            Last edited by brian Rupnow; 07-27-2012, 04:32 PM.
            Brian Rupnow
            Design engineer
            Barrie, Ontario, Canada

            Comment


            • #7
              I've just chucked the 1.5" diameter peice of cast up in my 10 x 18 lathe and experimented with a few cuts. Yes, it definitly is DIRTY. Lots of black, nasty powder off it. Can someone advise me as to speeds and feeds with this stuff, and should I be using HSS or carbide tooling? My lathe has 3 "hi speeds", namely 550 rpm., 970 rpm., and 1620 rpm. When turning mild steel with HSS I generally take my roughing cuts at 550 rpm and finish cuts at 970 rpm. I only use the 1620 for finishing cuts on aluminum. All of the stock I generally work with ranges between 1/4" up to 1.5" diameter. I can't take more than a .010 deep cut with my machine. (Thats .020" on the diameter) in mild steel or my lathe shudders and wants to levitate. Does this cast iron have a hard outer "skin" that must be broken through? The HSS tools I currently have ground have no top-rake, as it doesn't seem necessary in aluminum or brass, and it seems to work fairly well turning mild steel. Should I grind an HSS tool with top-rake to turn this material? What kind of finish can I expect to get with turning only----no emery cloth after the fact. Lots of questions I know, but any help would be appreciated, as I haven't worked with this material before. I am not too concerned about the finish on the cylinder, as I plan on reaming the final bore and I can emery cloth the outer diameter to a good finish if I have to , but I do want to be able to turn a really good and accuratly sized finish on the piston when I get to it.
              Last edited by brian Rupnow; 07-27-2012, 04:32 PM.
              Brian Rupnow
              Design engineer
              Barrie, Ontario, Canada

              Comment


              • #8
                Okay, guys and dolls---Its math time. I checked it out on the internet, and for grey cast iron the pundits recomend a rough turning surface speed of 24 metres per minute and a finishing surface speed of 41 meters per minute. Lets work with the roughing cuts first. 24 meters x 1000 divided by 25.4 divided by 12 gets you to 78.7 feet per minute surface speed. My material is 1.5" diameter, so 1.5 times 3.14 divided by 12 equals 0.392 feet around the circumferance of my material. My closest lathe setting to get where I want to be is 210 rpm. So---210 x 0.392 equals 82.32 feet per minute surface speed. (I had been trying to work with 550 and/or 920 rpm). To move on ahead to the finishing cuts, 41 is roughly 1.71 times faster than the 24 meters per minute, and since this math is linear, the rpm of the lathe should be 1.71 times faster than the roughing cut speed, so 1.71 x 210 equals 359 rpm. Also, 1.71 x 78.7 SF/M=135 surface feet per minute. My lathe has a 350 rpm setting, so that will get me a finishing surface speed in feet per minute of 350 x 1.5 x 3.14 divided by 12 equals 137.4 surface feet per minute, which is "pretty close" to the theoretical 135 surface feet per minute. I'm still not real sure on the HSS versus carbide tooling, but I will probably hog away the majority of the diameter with brazed carbide tooling and then switch to HSS with a fairly large nose radius for the finish cuts. Here is a link to the speeds and feed chart I used.
                http://www.roymech.co.uk/Useful_Tabl...g/Turning.html
                Last edited by brian Rupnow; 07-27-2012, 04:33 PM.
                Brian Rupnow
                Design engineer
                Barrie, Ontario, Canada

                Comment


                • #9
                  This is the finish I'm getting with a brazed carbide at 350 RPM (which is about 137 feet per minute surface speed.)
                  Last edited by brian Rupnow; 07-27-2012, 04:33 PM.
                  Brian Rupnow
                  Design engineer
                  Barrie, Ontario, Canada

                  Comment


                  • #10
                    I tried grinding a rounded nose on a carbide to see what would happen, but really there was no improvement over the finish achieved with a sharp carbide---just a bit more chatter. My best finish results so far are with a carbide at .005 depth of cut and 350 rpm. With a newly sharpened HSS which has a slightly rounded tip (about0.030 rad) the finish is about the same at 350 rpm. If I want to, with the carbide I can take a .010 depth of cut and it really makes the dust fly but leaves a rougher finish.
                    Last edited by brian Rupnow; 07-27-2012, 04:34 PM.
                    Brian Rupnow
                    Design engineer
                    Barrie, Ontario, Canada

                    Comment


                    • #11
                      As promised, here is the initial machining of the cyllinder. Since my chuck wouldn't open far enough to grip the 2.5" diameter peice of cast iron, I put the reverse jaws in to hold it. Of course this doesn't hold it by very much, only about 3/8", I used my dial indicator and tapped the free end around untill it was running true, then drilled the end with a center drill so I could support the outboard end with my live center. My chinese lathe has an extremely wide saddle, so that always creates some problems in getting the tool to cover the full length of what you are machining---Thats why the topslide is setting at the angle it is. The cutting tool is setting "backwards" in the pictures because I wanted to "face" as much of the end of the material as I could reach. The turning was all done at 350 rpm with a brazed carbide. I found that a .010 DOC was about optimum for my machine. Why did I buy 2.5" diameter material when the cylinder is only 50mm (1.97") diameter?---Because that was a "short end" left over at my steel supplier, so I got it cheap!!! Right now I don't know what my next move will be. Probably I should bore and ream the center hole before I attempt to cut the fins on the outside of the cylinder---However, with so much material stuck out past the jaws, and such a small grip on the material, I may try to set up my steady rest (which I have never yet used) on the cantilevered end before doing any drilling.


                      Last edited by brian Rupnow; 07-27-2012, 04:34 PM.
                      Brian Rupnow
                      Design engineer
                      Barrie, Ontario, Canada

                      Comment


                      • #12
                        SEE IT HERE FOR THE VERY FIRST TIME!!!! In the 3 or 4 years since I bought my lathe, I have never used the steadyrest. I didn't even know if it would fit!! It does, and its a beautifull thing. I dabbed a bit of white lithium grease in the area that the bronze or brass (I'm not sure which) tips contact the cast iron. Now I'm not afraid to drill that sucker.---Visions of disaster were running through my head brfore I thought of the steadyrest.
                        Last edited by brian Rupnow; 07-27-2012, 04:35 PM.
                        Brian Rupnow
                        Design engineer
                        Barrie, Ontario, Canada

                        Comment


                        • #13
                          And sure enough, it worked like a charm. You will see two "contact rings" where the steadyrest was moved during the drilling and reaming process. Thats because all of my big drills are quite short, my saddle is wide, and the "stroke" of my tailstock is only 1 1/2". In order to get all the way through the part, I had to move the steadyrest and saddle and tailstock closer to the chuck after my first round of drilling. I didn't bore the hole with a boring tool before my final reaming because there was no visible "wobble" of the drill like you see if the hole is not perfectly concentric, and even if it isn't "dead nuts" concentric the design of this engine is such that a small degree of eccentricity shouldn't effect it. I haven't taken the peice out of the chuck yet, and I'm thinking that with that steadyrest to help support the outboard end of the peice, I may be able to finish all of the turning in this one set-up without removing it from the chuck.

                          Last edited by brian Rupnow; 07-27-2012, 04:35 PM.
                          Brian Rupnow
                          Design engineer
                          Barrie, Ontario, Canada

                          Comment


                          • #14
                            The thru hole in my spindle is only 1 3/16" diameter. I can put the "normal" jaws in my chuck and hold the 2" diameter of the cast iron cylinder, but since the 2" diameter won't fit thru my chuck, I still end up with far too much "stick-out" past the chuck to machine the rest of the cast iron to the correct diameter. I can't cut the grooves for the cylinder fins with the steady rest in place, because it gets in my way. What to do?--- What to do?---I ran a peice of 7/8" cold rolled steel thru the finished bore, cross drilled a 5/16" hole thru the scrap part of the cylinder and the bar, and loctited a 5/16" pin in place. I left enough 7/8" bar sticking out past the cast iron to hold comfortably in my chuck, and centerdrilled the other end of the 7/8" rod to accept my live center.


                            Last edited by brian Rupnow; 07-27-2012, 04:36 PM.
                            Brian Rupnow
                            Design engineer
                            Barrie, Ontario, Canada

                            Comment


                            • #15
                              Here we are just about finished---
                              Last edited by brian Rupnow; 07-27-2012, 04:37 PM.
                              Brian Rupnow
                              Design engineer
                              Barrie, Ontario, Canada

                              Comment

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