Welcome to ModelEngineMaker !If you have problems registering or logging in, please use the contact menu option to request assistance.
JimThe interesting thing here is mass.The flywheel and crank can be half mass of a single.Port areas are up,piston speed less for same rpm if geometry ,ie bore/stroke ratio is the same and the charge air pumping is done by two resonant exhausts instead of one.To See if this kind of reason is valid it could be fun to scheme one as competitor to the configuration You have now,being State of art I would say.Have You ever considered releasing drawings to us two stroke lovers?The real stumbling block is to make a non overhung crankshaft that stands rpm on the far side of 500 rpm and still allowing this enormous flow of air and fuel.I will try to reread the whole thread and see how much dimensions You have given already.It has been a wonderfull mental journey until now.A happy new Year to You and all Your admireres.
- A Themac tool post grinder, turning at 20,000 RPM, is mounted to the compound to grind the cylinder's ID taper. - Since the ID of the collet is much smaller then the ID of the cylinder, the grinding stone's RPM is raised to 40,000. I prefer to use a Themac tool post grinder because it is the only tool post grinder that allows precise centering of the grinding stone's center, with its unique rotating mounting of the spindle.Jim Allen
Quote from: strictlybusiness1 on December 29, 2014, 03:45:59 PM- A Themac tool post grinder, turning at 20,000 RPM, is mounted to the compound to grind the cylinder's ID taper. - Since the ID of the collet is much smaller then the ID of the cylinder, the grinding stone's RPM is raised to 40,000. I prefer to use a Themac tool post grinder because it is the only tool post grinder that allows precise centering of the grinding stone's center, with its unique rotating mounting of the spindle.Jim AllenFascinating. Thanks again. You just answered my next question about tool post grinder. I guess its safe to say a jerry rigged die grinder would have insufficient accuracy, bearing/runout etc. attempting this level work? Would you mind telling me your model number or recommendation for ~14" swing lathe. I'm guessing they are $$, but always had a dream to maybe dual purpose the unit in a self made 'tool grinder' type machine. Re the rotary stone, what sort of abrasive type & grit progression do you recommend on chrome?Can you re-dress the stone mid-way a surfacing operation & somehow maintain the reference ID datum? Or you mean once set up, its put to work until completion of the grinding job?Do you prescribe a typical criss-cross hatching pattern after the grinding with separate tooling/procedure or is there some trick to replicating with the Thermac & lathe compound motion?
Jim, don't you grind on a "real" cylindrical grinder? On the lathe, I'm going to assume you're using a taper attachment, and not feeding with the compound? Setting the compound at oh 5.74° to get .0002" on diameter with .001" feed on the compound? I can't ever imagine feeding my old Clausing with the compound for grinding, or that Super 11 is a very nice lathe.Greg
OK. I didn't think such precision grinding was possible with the compound. I don't know if my lathe would be capable, but I'll give it a try as soon as I get my Dumore reassembled. Fortunately, most of my grinding needs will be straight.
Quote from: dieselpilot on December 30, 2014, 01:26:48 AMOK. I didn't think such precision grinding was possible with the compound. I don't know if my lathe would be capable, but I'll give it a try as soon as I get my Dumore reassembled. Fortunately, most of my grinding needs will be straight.I was going to ask a similar question but will pose in a different way. I always assumed the compound would be set to some nominal, shallow angle so a small incremental feed would translate into a teeny-er amount of stock removal at the grinder wheel. For example, if compound angle = 15 deg, Sin(15)=0.259, so a 0.001" compound dial feed = 0.000259"on the work piece? Is that the concept?But maybe we are talking about another issue in terms of the whole carriage movement against the lathe bed, or in this case, an angle/taper following type attachment?> I drill a 1/4" hole & cut with a band saw, 1/2" or 3/4" wide, 100 grit aluminum oxide wheels which are dressed round after mountingWhat kinds of tools are required to make holes in AO wheels like this? Do you then bond in a steel axle/mandrel before the final shaping & dressing? I had no idea this was custom wheel making even possible.
Hello JimIt is a pleasure to be on Your guided tourDo You use some kind of protective atmosphere during heating the maraging steel?