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Hi Chris, Still here still having a fun ride.On the valve front sounds like you've got it sorted, one suggestion make the valve "nut" from rod not the usual square material.......with rod it will fit nice & rotate just that little bit to help with the rod angle changes.Cheers Kerrin
Hi Chris,Your valve rod solution looks OK to me. Especially with steamers valve nut idea. I don't have experience using o- rings this way, but my reading suggests that many do. I assume you will use a high temp viton so it stands the steam temperature.Your great work is continuing in those bearing blocks. I admire the way there never seems any impediments, you just get going. You must work on some of those solutions in your sleep!MJM460
Hi Chris, Regarding your vertical displacement in the rocker arm, it is small at 3 thousandths. I would expect you will find it might actually be a bit different due to machining and fitting tolerance variations once you get it assembled. The usual arrangement would be to locate the centreline of the valve spindle halfway in relation to the vertical displacement in the arc the rocker, this allows 1 1/2 thou each way rather than 3 in one direction. This sort of tolerance might be hard to achieve, so I might suggest doing the best you can with machining then packing the rocker arm support, the cylinder bracket support or even a slightly different thickness gasket under the valve chamber walls depending which is the easiest or most satisfactory from your point of view. This might entail assembly-test-measure-disassembly-packing-reassembly-recheck, but it was how things were done with older steam locos because there was always a bit of variation that had to be accommodated. The accuracy achieved was just as good as CNC, but it was got after machining with filing, scraping and sometimes packing, this is the 'individuality' of steam locomotives. From my days as a machine tool maintenance fitter, very small but necessary adjustments when no very thin metallic packing is available can be had using good quality paper, made from rag is best but not absolutely essential. It is a bit intuitive as you need to 'guess' the crush. Believe it or not I have seen roll your own cigarette papers used to get perfect alignments. One thing with the valve gear on the Lombard. I would be most interested to know if the eccentrics are set to give negative lead in full gear, this was reasonably common with locomotives using Stephensons valve gear. Its lead increases as one 'notches up' which is useful at speed but better starting can be achieved with negative lead. In the model this may be irrelevant but it might have been a design consideration with the full size one, if you could find out and enquire by how much I would be very grateful. Regards, Paul Gough.
Really nice. If you stare at them long enough at this time on a Friday afternoon (beer thirty they almost start to have "faces" . NS, Try it Eric
Damn nice Dog, you just keep setting the scale bud and those bearing block are looking to cool. Those elfs are sure busy little fellows huh? Still following some great craftsmanship Dog!Don