Can someone with more knowledge than me tell me if it's ok to mix case halfs when building saws? I see them for sale online as individual halfs but are they all matched machining wise. Common sense tells me each set at the factory would go through a machining process to match crank bore and jug mount surface for square and fit.
Boy thats a tough call.
The concentricity of the crank bores to the crank journals axis, and the flatness of the deck mating surface are the big ticket items in my mind and ive definitely seen mismatch parting lines on the deck before.
Im sure the by the book crowd will say mismatch cant be done. And im sure i could compensate for issues and make it work. I guess you have to decide if you can afford the risk.
For the most part u can match them up and the saw will run. Mixed red and orange 372/2171 cases once. Saw still runs. Might not be a good idea with some model changes like pre 2010 and post 2010 oe vs. xt cases on the 372's. No idea with Stihl's or other brands. A little "misalignment" will add a little heat to the bearings. A lot will kill them over time. Fact is there will always be a little even with new saws. Manufacturing tolerances and all. Might mention bearing cages....but don't want to start a oil type discussion :) ( some handle heat better than others )
You could could probably get away with it .However most times if you get the bones of a donor saw or three one should certainly have a good case .I have seen more than one case they must have used a 3/4" socket wrench on, broken ,junk . Proving once again some people could destroy an anvil with a feather .
Thanks for the replies. Good info! My gut says they would be matched with machining
Quote from: donbj on June 26, 2021, 11:51:56 PM
Can someone with more knowledge than me tell me if it's ok to mix case halfs when building saws? I see them for sale online as individual halfs but are they all matched machining wise. Common sense tells me each set at the factory would go through a machining process to match crank bore and jug mount surface for square and fit.
No, as you stated, they are put together, torqued, then line bored. But they are all so precise ie castings, machine work, I have seen it done with no issues many times.
I would say avoid doing it that way, but it you have exhausted all options or the parts are made from unobtanium, then give it a go.
Like the man said; if all avenues are exhausted, do whatcha gotta do!