Thread: stress grades for wood

What you are thinking of is engineering stiffness which is separate to stress grades

Stress grades are a method of identifying the strength of a piece of timber by observing the defects in it and comparing them to known data.

you can have visual stress graded and machine stress graded.

all structural hardwood must be graded as per australian standard 2082 for visualy stress graded hardwood.

it depends on defect timber grain and species.

the papework for as2082 is 50 pages long to give you an idea of whats involved.

weisyboy is right - there is visual stress grading and machine stress grading see here for explanations: http://www.timber.org.au/NTEP/menu.asp?id=90 and http://www.timber.org.au/NTEP/menu.asp?id=91

Thanks for the fast responses!


so I can not use it for a structural calculation then....

Where to get the stresses/stiffnesses? Read 8N/mm² somewhere..

i dont think they are avalable.

you gotta use span table to work out what goes where.

Originally Posted by weisyboy

all structural hardwood must be graded as per australian standard 2082 for visualy stress graded hardwood.

Not totally correct Carl, all structural timber is to be graded, but there is no specific mention of how that grading is done it can visually stress graded (using AS2082) machine stress graded (a pre-determined load is applied to a piece of timber by a machine and the resulting deflection is recorded, with this deflection a stress grade can be assigned to the piece of timber, not using AS2082) or it can be machine proof graded (relies on applying a pre-determined proof load, if the timber doesn't fail under the proof test then a grade can be allocated, again not using AS2082)
Although if you want timber graded relatively cheaply (not buying one of these big machine-like vices on steroids with half a dozen super computers hanging off it, then grading to AS 2082 is pretty cheap 2-3 day course and few hundred bucks and you're on your way.

allan is right.

what i mean to say was all structural hardwood must be graded. visual gradign is done to as2082

I know sometimes I get a bit picky....

Geese I'm getting a bit excited about the Showdown on the weekend!!!

yer i get like that to.

o yer cant wait.

i will get there thursday arvo so if anyones around give us a call.

Just want to make some funny structures, so there is no span table or parts list or so.

http://i212.photobucket.com/albums/c...595/canopy.jpg

http://i212.photobucket.com/albums/c...en595/tank.jpg

so I was hoping I could find some values for the wood. The software comes with some already.

There's a chart of a generic density/bending strength/compressive strength relationship here, as well as lots of other stuff.

http://www.auf.asn.au/scratchbuilder/timber.html

Most Oz hardwoods are at the high end of density - 900+kg/cu.m.

and what exactly are those pictures of?

there as tables for almost everyhting

one is a tank stand with 32mm decking, the other some funky canopy.

well the tanks stand will have a span table to use.