Moisture - shrink ratios fir and cedar

[carver45]

Hi guys,

I am new to this forum and find it great. A lot of people sharing great information. I just purchased a mill and need to find a source for tables on moisture versus shrinkage rate for fir and cedar.  I am not sure if I am using the right terms. So I  will put it this way.  When I cut a green log of fir or cedar how much will it shrink. 

Thanks
Chris

[beenthere]

Shrinkage information for wood of various species is found in the Wood Handbook.

Go to:
Wood Handbook

and look under Chapter 3

[Brucer]

Hi, Chris. Lessee - Vancouver Island, so that'll be Western Redcedar, and (I'm guessing) Douglas-Fir.

Shrinkage doesn't start in Douglas-Fir until the moisture content falls to around 28-30%. Then, for every percentage point the moisture content falls below that, you'll get
  - in the radial direction (centre to outside), 0.0015 shrinkage;
  - in the tangentail direction (around the rings), 0.0026 shrinkage.

For WRC shrinkage starts at around 22%. For every percentage point drop below 22%, you'll get
   - in the radial direction, 0.0011 shrinkage;
   - in the tangential direction, 0.0023 shrinkage.

For example, if you're going to dry the Cedar to about 10% (reasonable outdoor moisture content in your neck of the woods), for 8" wide boards you'll be looking at (22-10)*0.0011*8" = 0.11" shrinkage in the radial direction. In the tangential direction, (22-10)*0.0023*8" = 0.22" shrinkage.

Unless I'm sawing for a specific grain pattern, I usually average the two numbers -- in this case about 3/16" for the 8" board.

What kind of mill ya got??

[carver45]

Hi Lessee,

You are not to far away. I have a woodcraft 20 -30a powerer by a kohler command 25 motor. It is fully hydrolic. I just baught it and will start running it in the new year.  It is suppose to cut between 200 to 300 bf an hour but I will be lucky to start out at 25 bf an hour.

Their is a place up the road that wants to do a 50 50 split for a bunch of fir and hemlock. I thought it would be a good practise run. He just wants it cut into kants(is that spelled right?). Sounds good until I develope a market and get enough pracitice to cut straight good qualiity boards.

I am a self employed chainsaw carver and am trying to get into something that has a little more of a reliable cash flow. I have been up late reading the posts and found that cash flow could still be a problem with a mill. But I love wood and need a rest from carving, so a mill sounds logical.

Lessee, do you have formula for figuring out board feet. I can do it in my head but still finding it diiffuct for things like a 10 foot 8 by 8. 

Have you got snow over there?

Bye for now
Chris

[beenthere]

""Lessee, do you have formula for figuring out board feet. I can do it in my head but still finding it diiffuct for things like a 10 foot 8 by 8. ""

Go to the 'Forum Extras' in upper right (under the trees) and you will find a red tool box, that will have a board foot calculator, among other 'extras' for your convenience.

[Brucer]

Have you got snow over there?

15" so far. It all fell in November. Nothing at all this month, and none in sight. The skiers are starting to participate in wierd rituals (like sitting around in bars, drinking beer, and whining :D)

Board foot calculations --> pocket calculator, plus paper & pencil to keep track ;D

[Don P]

This is a good shrinkage calculator, it uses the info from the Wood Handbook that Beenthere linked to;
http://www.woodbin.com/calcs/shrinkulator.htm

Shrinkage in a large cant is normally considerably less than the calculations give. Shrinkage numbers were worked out on small clear boards that were free to move. a large piece of wood develops drying stresses and checks that greatly reduce the overall shrinkage.