QWe rip a long, narrow stile (about 72 x 3 in.) and then send it to the moulder for profiling. We test for proper MC and casehardening stress. However, more than 50% of the pieces have 3/16 in. length- wise bow, just after moulding or a day or two later. What are we are
AConsider your stress tests. Transverse (or across the grain) case-
hardening stress is measured
using a prong-test where the legs
or prongs (cut about 6 in. long
and one-quarter the thickness of
the lumber) should be parallel
with each other or nearly paral-
lel. If there is transverse stress,
lumber pieces will cup when
Lengthwise warp is a different stress and will not show up
using the prong test. Instead, I
suggest that you cut a 24 in. long
piece of wood from a piece of
lumber about 8 in. wide. Then
rip this piece into two 4 in. wide
pieces. Put the two ripped pieces
back together and they should fit
with any gaps being less than the
thickness of a dollar bill.
Wood will bow, as in your
QI have some lumber that is cupped quite a bit after it has been
case, more if the grain is not per-
fectly parallel to the sides of the
piece. When making narrow long
products from wood it would
be best if the sawmill sawed the
lumber parallel to the bark and
did not use crooked logs.
kiln dried. Is there a way to flat-
ten this lumber by putting water
on one face?
AFlattening cupped lum- ber is almost impossible to do. The best chance
By Gene Wengert
at flattening can be achieved
by quickly rewetting the convex
side. Use hot water. It will try to
expand, but it cannot do so. As
a result, it will develop what is
called compression set. Do not
let water go beyond the surface
(maybe 1/4 inch) on this convex
What you need to know to optimize your
Pointing a finger at joint problems ..............
Getting the most from the moulder ..............
The cuts count ........................................
Solving erratic cuts on the ripsaw...............
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