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An excentric spindle would work OK to adjust the backlash between two gears. However, in the W165 gear trian, each idler is in contact with more than one other gear, so an excentric sleeve would not have worked.
Thank you for your reply, Mike, and the drawing image. It just gives me that much more respect for what you are accomplishing.QuoteAn excentric spindle would work OK to adjust the backlash between two gears. However, in the W165 gear trian, each idler is in contact with more than one other gear, so an excentric sleeve would not have worked.I agree with that. I'm afraid I didn't describe my idea very well. The eccentric spindle would rotate within a sleeve with an eccentric bore. That sleeve would also be free to rotate within its gear case bore. If I'm correct that would seem, in principle anyway, to allow the idler gear lash to be adjusted for both driven gears by adjusting the two eccentric axes independently. Of course, means to lock both the sleeve and the spindle would have to be provided, plus means to rotate each with some precision. I don't question for a second that your idea of how MB accomplished the job is the correct one, I was just imagining/day-dreaming a possible alternate way.
Now let's get back to making chips.
Mike, did you try setting up the gear train on a "sacrificial plate" to work out the gear centerlines? & machining the bores "theoretically" where they should be? I would have to think that even mass produced gears would have some "level" of accuracy & could be easily changed out.(?) In full scale... What kind of accuracy is required for your model? I understand the timing requirements, but chain drive cam timing has to have a lot more "slop" & proved itself in production scenarios (not comparing to model making..). Not criticizing your design, I'm just trying to keep up following along. John
Looking good The question, as always, is how good does it have to be for a model display engine? I know I don't have much tolerance with my fuel injection systems but for a valve train drive system as long as the gears engage and don't jam how precise do you need to be???