[Strawbale] lumber grading (was: plwood vs. osb for arch gussets)

[Derek Roff]

> You can saw and plane your own lumber, but it can be quite difficult
> to  track down a free-lance lumber grader who will bring along grade
> stamps  and go through your piles.

I've read, in Forest Products Laboratory publications, that fairly 
accurate stress-grading of dimensional lumber is possible in the field, 
by an owner-builder.  What's your opinion, Chris and RT?

I second RT's concern over the suitability of the rough-sawn wood 
surface for a good glue bond.  I have seen band-mill surfaces that are 
amazingly good, and others that would not allow a strong glue joint. 
With most common woodworking glues, the strength of the joint decreases 
quickly when the thickness of the glue line (or, more accurately, glue 
plane) increases beyond about 0.13mm (.005").  Surface roughness, the 
integrity of the wood fibers, and larger scale deviations from plane 
(ripples and undulations caused by blade drift, and cupping/warping) 
all effect the strength of a glued joint.  Of course, using dry wood 
and fresh glue of the proper type is essential for a strong, reliable 
bond.

Derelict

Derek Roff
Language Learning Center
Ortega Hall 129, MSC03-2100
University of New Mexico
Albuquerque, NM 87131-0001
505/277-7368, fax 505/277-3885
Internet: derek at unm.edu