I have a DeWalt Biscuit Joiner that I use to make boxes or cabinets.
That is 2 sides and a top and bottom.
The fence for the joiner is set at a height of 3/8" and is is down, or
parallel to the blade. I am using 3/4" plywood.
My method is to place the top and bottom pieces on a flat surface with
their inside faces up. I have one end of a piece overhanging whatever
surface the piece is on. The other end is clamped to the work surface.
I then place the joiner wherever I have made a mark and position it so
the fence is pressed against the end edge. The slot is then made into
the inside face, parrallel to the end edge. The distance from the end
edge is the same as the distance of the fence from the blade. I now
lay the side pieces down with their outside faces up. I place the
fence of the joiner on the outside face and hold it there. The joiner
is pushed against the end edge of the side and the slot is cut. I then
place the biscuits and glue and clamp the pieces together.
My problem is that when the glue is dry the top and bottom pieces
overhang the side pieces by about 1/16". This happens at all 4 joints
and has happened on several cases I have built.
Can anyone tell me what I am doing wrong? I use a router with a flush
trim bit to correct things but I would like to avoid having to do
Thanks for any and all help.
Kinda hard to tell from the description (got a headache, not your fault),
but there is one rule you want to follow without fail: Mark your reference
surfaces/faces (the ones you want to be flush to each other); and always
make cuts from that "referenced" surface, face, edge.
If your tool is in good shape and the blade is not wobbling, it's pretty
hard to not come out with flush surfaces providing you consistently cut ONLY
from that "reference" surface/face.
Do things line up when you do a dry fit?
If your biscuits are too loose in the slot due to a dull or wobbly blade
cutting an oversize slot, you may want to check your clamping technique.
In that case, these might help:
Scroll down to "I-Beam Supports/Clamp Assists".
Check the slots you've cut in the ends of the sides, and you'll find that
they are about 1/32" closer to one face than to the other.
The procedure you describe should produce dead-on flush fits, regardless of
the thickness of the stock or the setting of the joiner.
If your description of the procedure is accurate, then you're somehow
reversing the side pieces inadvertently when you assemble the case.
I can think of two ways this could happen:
a) you lose track of which faces are inside and which outside
b) you inadvertently switch the left and right sides, and the front and back
sides (which would have the same effect, putting an inside face outside).
The problem id that you are not using 3/4" plywood. The 3/8" mark is not
the center of the plywood sheet. It is, however, making the slots 3/8" from
the edge of the side, thus the mis-match.
It may be OK if you flip the top and bottom plywood over so that the 3/8"
slots align. You can make fine adjustments until they do align. Meantime,
measure the true thickness of the plywood.
With all due respect, Ed, if he has described his procedure accurately, and is
not inadvertently reversing the pieces before assembly, it won't make any
difference whether the plywood is 3/4 of an inch or 3/4 of a mile thick, the
slots will still be in the right place.
Tweaking the adjustment of the joiner until the slots are exactly centered is
an unnecessary waste of time and wood: no matter what the thickness of the
wood is, no matter what the distance from the reference edge is, the machine
always cuts the slots at the same distance from the reference edge. If the
reference edges line up, the slots will too. His problem is that his reference
edges aren't aligned properly when he assembles the case.
Can't tell from here if he's inadvertently swapping inside/outside faces, or
left/right and front/back pieces, but he's sure doing one or the other.
You are correct that the distance does not matter if the pieces are oriented
the same way, BUT, stuff happens. Getting the slot centered, while not a
necessity, has the advantage of making the parts universal. While you say
it is a waste of time and wood, if it solves his problem, it eliminates the
extra trimming step he has now. . Either way works as long as you do the
layout and mark the parts for the proper side to match.
3/4" isn't made any more. Measure it! It isn't 3/4" anymore.
It is likely 11/16. Being 1/16 thin because it is metric or they are stealing
1/16 due to some tree hugger law or judgment.
Doug Miller wrote:
It doesn't matter whether it's a full 3/4" or 1/16" shy or whatever. If he's
cutting slots at some fixed distance, whether it's 3/8", 5/16", or
whatever, from some reference point on each of the mating pieces, and
installing them with the reference points in the correct relationship to each
other, everything will fit. His problem is that he's reversing the pieces
somewhere, somehow, between the cut step and the fit step.
My guess is that the OP *thinks* he's cutting slots exactly in the center of
what he *thinks* is true 3/4" plywood and therefore *thinks* the orientation
of the reference surfaces doesn't matter.
It's true that if you really are cutting slots in the exact center of the
plywood, then the orientation of the reference surfaces doesn't matter -- but
that's not the optimal way to look at the problem. Things work much better if
you realize that if you keep the reference surfaces oriented correctly, it
doesn't matter if the slots are in the exact center of the plywood, or a
little bit off-center, or a lot off -- the pieces will still line up.
That's provided everything else is done properly. He might not be holding
the joiner completely flush with the wood. There might be a burr on the
joiner. The wood might not be cut perfectly straight. Hell, even the
biscuits might be slightly undersize or otherwise flawed. There could be any
number of reasons his cuts are not lining up properly. If everything else is
as it should be, then Doug is correct.
Well, yes, but those issues will cause misalignment regardless of what
technique is used. My point is that instead of obsessing over getting the slot
exactly centered in the workpiece, it's much simpler to just make sure the
reference surfaces are in the proper orientation when the piece is assembled.
Sure, you're right. As far as alignment goes, it doesn't matter where the
slot is really as long as the mating slot is lined up with it. Having them
centred only adds to the strength of the join and has nothing to do with
Sheeesh, folks! Read the above and take it to heart ... if you want to give
yourself every chance of success in this endeavor, in a world where things
will go wrong if given a half a chance, there is NO better method ...
So Kim comes up to me this morning with a dowel that she located in "my"
shop and wanted me to cut it "ABOUT" in half. She is waving that thing she
brought over to show you and yours last night and wanted a dowel to put in
the end of it. I had already forgotten "what she sewed" was for and figured
she wanted to use the dowel to hang the piece on the wall. Soooo she says
the dowel needs to be shorter than the width of the thing she made but
almost to the ends. I laid the dowel on the thing she made and marked
where the cut should be with her watching and agreeing with the location of
where the cut should be.
I went out to the shop and cut the dowel and brought both pieces back in.
As it turns out I had actually marked and cut the dowel "ABOUT" in half as
she had requested.
When I handed the 2 dowels back to her she compares the lengths and says
"they need to be the same length" !!!!!
Ah, yes ... the cry of frustrated testosterone being overwhelmed by the
logic of estrogen. We know it well! :)
That we do.
My favorite is the which restaurant do we eat at routine. I go, "Where do
you want to eat honey?" She sez, "Oh, anywhere is fine with me." I go, 'OK,
we will eat at the __________ ." She goes, NOOOOOOOOOOOOOOOOOO!!!!.......,
we can't eat there!!!!"
Feminine logic at its best.
Being a card carrying coonass, I'll eat just about anything, so I just let
her decide ... of course, and once the menu is presented, it has to be
properly scrutinized for substitutions, and lengthy negotiations commenced
with the wait staff, because there is obviously no way in hell you can just
simply accept what is on the damn menu, eh?
There was a story in the news this morning about a hermit in the piney woods
of East Texas. I've begun to understand the appeal ....
Absolutely! I have learned through out the years that proper technique or
method is EVERYTHING. I seldom measure anything on a project anymore except
for the length and widths that have to be a particular measurement. The
more things you can do with out a tape measure the less mistakes you will
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