[Strawbale] lumber grading

[Derek Roff]

It's been a while since I read about stress-grading lumber in the 
field.  The basic idea was that measuring fairly small deflections with 
modest loading of a beam could give acceptably accurate indications of 
how the beam would perform with greater loads.

If I remember correctly, one suggested approach was to stack some 
cinderblocks (CMU's) at an accurate distance (say, eight feet apart) to 
support the ends of the beam, and a few in the middle to give a stable 
platform for measuring the deflection.  Put the beam on the blocks, 
load the middle with a couple of bags of cement (a fairly accurate and 
repeatable load), and measure deflection.  Tables would convert the raw 
measurements to acceptable spans.

I don't have any memory of the proposed deflection measurement device, 
but a cheap dial runout gauge might work.  I'll see if I can dig up 
anything on this approach.

Derelict

> Derek Roff wrote:
>> 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?

>  Chris Green wrote:
> This is news to me, so I don't have an opinion one way or the other.
> Right now I can't even guess how one would do that without a lot of
> those gizmological wonders RT frequently mentions.

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