On Mon, 21 Nov 2005 09:19:53 -0600, Duane Bozarth wrote:

[snip]

Plus the one I've had w/ the automated "planer as jointer" machines--how
do you control and drive a non-flat piece of material past the cutter head
w/o distorting it to get the initial flat reference surface? That's the
reason for the jointer initially and why working a piece through the
planer first (unless it's so thick as to be essentially rigid) doesn't
work.

Excellent point.

Here's where I have to again invoke Nukleer Seekrits. I can't answer your
question at the moment by telling you HOW I do it.

You're right, though -- take a cupped/bowed/twisted hardwood board, say
4-6" wide and maybe 5' long.

Try to run it under a rotating planer head.

You need rubber drums to hold it down and feed it against the force of the
knives pushing it back at you. Those feed-drums have to squish the
(flexible) board against the table to keep the board from kicking right
back out the infeed side. So they also have to squish it into a flat
profile.

Once they're done trimming, the board springs back into its previously
cupped/bowed/twisted state, and the "flat" face you just put on it --
ain't.

----------------------

A jointer works for this task BECAUSE it uses a flat table reference
surface, using YOU for the feed force (not rollers -- and I didn't even
mention the snipe that feed rollers invariably cause). You "average" the
bottom surface, based on where the board contacts the infeed and outfeed
tables (which is why jointers need MUCH longer tables than a planer). The
bits of the bottom surface that stick out the most get shaved off, over
multiple passes, until the surface has been "averaged" down to a flat,
REFERENCE surface, as you mentioned.

-----------------------

So - I can't tell you HOW my machine design DOES avoid these problems --
I'm patenting some of the key ideas and can't disclose them publicly. But,
if you don't need to "squish" the wood with rollers -- you avoid the
problem.

Andrew