I think you're right - in theory at least.
I use hand planes to joint all of my laminated surfaces (and I don't use
sheet goods, so there are a lot of them). Using the push harder to take more
off trick works to a certain extent, but here's my method (and I do
everything from small jewelry box panels to 8'+ table tops):
Assumption: stock has been prepped and is close to square and straight
Plane A is a #7, fairly coarse cut
Plane B is another #7, but set super fine cut, super tight mouth
Lay out the planks as you will use them (grain, appearance, cupping, etc.
allowed for) MARK THEM. Nothing sucks more than getting them all perfect,
then stacking them up and having them not match because they somehow changed
order....
Start with the first joint. Butt the 2 plank up to each other. Lift them up
and eyeball where no light shows through. Mark those areas with a pencil the
line should indicate how much to take off (for long boards, I use a white
formica counter top instead of trying to hold them up.
Using plane A (Rarely can I get away with starting with B), take an educated
guess at how many swipes you need to get close, planing the areas WITH the
pencil lines ONLY. Taper your cuts going in and out (most of them will be
starting and ending in the middle of the plank). Unless they are really out
of whack, I only work one plank (one side of the joint). Your pencil lines
should go away, so you'll have a fresh surface for the next round.
After you've done your best guess, butt them back together, and repeat. Keep
checking, marking, and planning until you're close, then switch to plane B,
and keep going.
When you're done no light showing through the joint. Move to the next joint
and repeat. Note that these joints won't be 'straight' in the true sense of
the word - they'll be imperceptibly wavy, but they'll be perfect matches.
Getting truly straight joint is a much more tedious process - search the
archives for how to make a straight edge for details....
Good luck
-James D
-----Original Message-----
From: oldtools-bounces@r...
[mailto:oldtools-bounces@r...] On
Behalf Of
ruby@m...
Sent: Thursday, July 24, 2014 2:45 PM
To: oldtools@r...
Subject: [OldTools] Plane behavior
On a guitar, you have to join the two pieces of the back and the top with a
joint that will not pass light. These pieces of wood are less then 1/10"
thick and with the top - the glue is all ya got.
On one of the forums, someone posted about an English builder who says do
this: On these 22" or so pieces, get close, then start about 2-3" in from
the end and take a pass or two til 2-3" from the other end - in other words,
create a tiny hollow. Now take 1-2 passes over the full length and you will
be flat.
Got to thinking about this and came up with an explanation.
Am I
1) Spot On
2) Partially Right
3) Full of Horse Hockey
The hand plane is not at all like a power planer - the *l*ctr*c tool has 2
beds that stay parallel (hopefully) as you raise and lower one, so the
workpiece travels smoothly from the infeed to the outfeed tables and remains
parallel to the bed.
Think about the toe of the handplane laying flat on the piece as you start
the cut. Start pushing the plane and the blade then removes a little bit of
wood and this causes the back end of the plane to be lowered (we are talking
tiny amounts here) to a new level lower than where the toe is, so the plane
is now tipped up a tiny bit - the tool and the workpiece are no longer
parallel. Until the bed of the plane is totally on the workpiece there is a
slight thinning of the cut. Once the end of the bed is on the piece of
wood, the angle of the raised toe stays the same and the cut continues flat.
Then at the end, your tendency is to push on the toe which causes a little
bit of of over cutting at the very end. The result is a very slight hump in
the center of the board. The numbers are very small.
This supports the notion of scooping out a tiny amount of material in the
center before a final pass or two.
My belief is that when craftsmen made their living with a plane, it didn't
much matter if the bed was absolutely flat because they learned how to
compensate during the length of the cut to make it flat - that's why we
rarely find flat plane soles on well used older planes - it didn't much
matter. He could put downward force on different parts of the plane at
different times to compensate for the difference. We are told to do this,
but we are told in a generic fashion, not in a way that might help with
different lengths and flatnesses of plane beds.
But we mere mortals don't use our hand tools enough to be that proficient,
so every ounce of advantage we can muster is helpful. Flatten that sucker!
And one of the amateur luthiers uses a #7 - 22" of plane on a 22" piece. Is
this making it easier or more difficult to get a flat surface?
Food for thought - did I get it right?
Ed Minch
I think we did something like this 10 years ago.
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