Raised Grain and Sawmill Blades
A discussion of how blade characteristics might relate to roughening of the lumber surface. July 16, 2009
Question
I have a Woodmizer LT-40 sawmill. It has been stored for about five months without being used. When we brought it back out we performed the regular PM on it, (lubrication, oil change, calibrations, replaced rollers and belts, etc.) When we began cutting again I started to notice that it seemed to be raising the grain on the wood very badly. The cuts are straight and not dipped or wavy but the wood was not as smooth as it used to be. The logs we were cutting have been sitting out awhile (yellow pine, 6-10 months) but the blades we used were brand new. If anyone has any ideas or could explain why I am getting such a rough cut I would appreciate the help.
Forum Responses
(Sawing and Drying Forum)
From contributor A:
On dry logs that is not uncommon. I see it on western red cedar a lot. Cut some old eastern white pine logs from a log home and the grain raised on it. Put on a fresh red oak and see how good it cuts.
From Gene Wengert, forum technical advisor:
This also shows up with frozen logs. Please describe the blade you are using.
From the original questioner:
I know they are Woodmizer all purpose blades. I bought the sawmill used and they came with it. I am planning on buying new blades but didn't want to waste the blades that came with the sawmill just because I wasn't exactly sure what measurements they were. When the grain in raised like it has been doing can it cause any problems (drying, selling) even if I am only selling the wood as rough cut lumber?
From contributor W:
Woodmizer has several different profiles, multiple thicknesses and widths for the LT40 mill. If you look on the outside of your blades, about eight inches or so from the weld, you will see a series of letters and numbers stamped into the steel, something like this:
B4751589S.
The 158 is the blade length in inches, the 9 is the degree of hook. Woodmizer sells 4, 7, 9, 10 and 12 degree blades. Generally, the harder/knottier/drier a log is the lower a hook angle you would want to use. So if you are cutting relatively seasoned pine with a 10 degree blade, it will 'rough up' the lumber more. If you use Woodmizer's blade selector as listed on their website, you will see recommendations for 4, 9 and 10 degree blades in .045 and .055 thicknesses as well as 1 1/4 and 1 1/2 inch widths. If you have a lot of those logs to cut and if the surface is unacceptably rough and if fresh logs cut fine, you might want to consider changing the blade settings.
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