Hi Bob,
Make sure you get an auxiliary oiler if you’re going to run a bar that long on your 066. One of my buddies toasted his 660 milling 24” live oak with a 36” bar w/o aux oiler - one cut too many between sharpenings was all it took. Probably would have survived with the added cooling of the aux oiler.
The type of chain isn’t nearly as important as keeping it extremely sharp, particularly when you’re pushing a saw to its thermal limits. Make sure you have at least three sharp loops any time you prepare to mill. Switch after every two cuts in hardwood, or stop to thoroughly sharpen (30+ minutes), and you probably won’t cook your saw.
Although I own the better part of $1k worth of Granberg loops, I mostly find myself using Stihl RM loops filed down to 15-20 degrees these days. Cuts faster and no over hardened cutters, which are a nightmare when hand filing. However they modify those cutters on the Granberg chains seems to be resulting in a greater and greater percentage of the skinny ones being turned almost carbide like. It was only a few cutters per loop on the first loops I bought several years ago, now it seems to be over 50 percent of them on the loops I’ve gotten in the past year. Literally destroyed two brand new save edge 7/32 files tuning up a 167dl loop yesterday. Took me over an hour
The Granberg chain definitely cuts a bit smoother, and is a little easier on the saw if kept razor sharp, but I find that with the proper technique I can get almost as smooth with the RM. Big slabs almost always need to be thoroughly surfaced with a router sled anyways, so unless you’re trying to sell them rough sawn and green, smoothness of cut isn’t that big of a selling point.
If you haven’t already, check out BobL’s CSM 101 sticky in the milling sub forum on the other site - tremendous amount of useful wisdom there!
