False Beats

J Patrick Draine draine@mediaone.net
Sat, 23 Sep 2000 09:25:12 -0400


>  >
>>  >  do you get nice clean sides, or are they kinda choppy? Any
>>  >problems with this (actually I would think a bit rough surface will give
>a
>  > >better glue joint!)?
>
>
>Well show us his scientific evidence so we can make up our own minds.



For starters you can check out his "Understanding Woods" & 
"Identifying Woods" if you want see if he seems to know something 
about wood or not.

I mus admit that in this case we may be comparing not just apples 
with oranges, but apples with watermelons. The examples that Hoadley 
was discussing (in the PTG classes I attended) was gluing two *flat* 
surfaces together. Alot of his consulting has been with furniture 
factories, and he always insists on the importance of preparing 
surfaces for gluing just before gluing the pieces together. That is, 
don't sand or plane two surfaces, and then leave them lying on your 
factory workbench, as slight (microscopic) coatings from the nearby 
refinishing department will be piling up on the previously clean 
surface over the weekend.
Aside from contamination, Hoadley noted that freshly planed or fine 
sanded surfaces will take a much better glue joint than a "roughened" 
or scored surface.
On the other hand, a "rough sanded" piece of wood may make a better 
joint than two flat pieces that were last planed or sanded months or 
years earlier because the flat surfaces are so contaminated with 
oxidation, sundry pollutants, hand oils, etc. It's not the roughness 
of the piece, but the removal of the layer of contaminants that 
improve the strength of the bond.
>  The hammer shank must be scored
>to allow glue to ooz out.



Well this is where I *concede* that with shanks and plugs we're 
dealing with forcing (or close fitting) a cylinder in a hole -- a 
very different dynamic than gluing two flat planes together. Scoring 
does essential for glue squeeze out in this case.

At any rate, I didn't read Hoadley's sources or research on this 
particular subject -- I was too busy with language classes & writing 
a thesis to audit any of his classes in the Forestry department at U 
Mass. Hopefully he'll be teaching again at a future PTG institute so 
we can ask for more details.

Patrick


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