Building a table, think torsion box-like.
Will consist of several pieces of ply (it's not
for furniture, sort of a hobby table), that
interlock through slots. Cross pieces will
lock with long-wise pieces.
I got to knock out about 20 or 30 of these slots, or
thereabouts. I'm thinking building a router template
then using a spiral bit with a collar around the template.
Those drawer joints looked a bit *too* tight; if you have to hammer
together, you risk splitting out the dadoes (and you WILL split them
add in the glue). Best to slack off the fit by the thickness of a
For $65, probably a nice tool if you're doing production work. Cheap
Bridge City, actually.
That looks like a nifty tool. To set a groove kerf without a special too,
take any piece of scrap with at least one straight edge. Set your rip fence
somewhat narrower than the scrap and rip it to any arbitray width. Now take
a piece of the stock that you want to match the groove width too, and place
it between the fence and the 1st scrap piece. It needs to be long enough
to act as fence itselt. Rip the scrap piece again, this time so it is
riding against the sample piece being held against the fence. The cutoff
produced will be exactly (within the limits of your machine's accurace)
the width of the stock less your saw's kerf.
Often wrong, never in doubt.
Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf. lonestar. org
The router will cut relatively slowly, make lots of noise, and make
A biscuit joiner will cut quicker, make lots of noise, make coarse
A mortising chisel (square chisel with central auger-like bit) will
cut more quietly, make shavings instead of dust, and is intermediate
An auger or Forstner bit and chisel and mallet will do it slowest,
shavings (chips), and is the most fun. For learning about wood, and
sharpening of chisels, everyone should do this at least once. 20 or
though, starts to seem excessive.
Depends on how long the slots are to be. If not too long, a table saw would
be worlds faster, you could stack the pieces and cut slots in each at one
time...position stack, cut, position stack, cut. Et cetera.
When I built my last torsion box affair (served as a six+ foot shelf/
table top) the internal cross members were relatively thin (quarter-
inch or so) and the slots were half their width (less than half the
thickness of the finished torsion box).
I think a ten-inch TS will cut in excess of 3" at ninety degrees. Less
with a DADO blade.
But, as someone pointed out already, the OP provided insufficient
detail from which to determine a best practices approach the project
Some of the responses have indicated
that I failed to give more detail.
Hopefully, this will help.
I want to build a grid of interlocking pieces
of plywood (3/4"). Each long piece in the grid
will be 4 feet long, the cross piece is also 4 feet.
The height of all the pieces is 4 inches. On top
of this, I'll put a sheet of 3/4 ply. I don't need to
make the top super flat as in a torsion box just
ok will do. The idea is that I'll be able knock
this down when I need to, which I expect
could happen over time. Want to end up
with a grid 4 feet by 4 feet.
I was thinking of a grid of three pieces in length and 5
cross pieces with one at each end.
The interlocking slots need to be all the same
depth, width and in the same spot on each corresponding
pieces (each cross piece needs to be identical, each
long piece the same).
I was thinking of a dado cut, but just not sure if
an 8" dado would cut that high, and to be sure of
consistently in the slots, I'd would have to gang
the pieces together. Seems to be a bit of
I was thinking of making a template out of MDF or
ply. A router could be used to ride the template and
cut out the slots.
Someone suggested to me use of a jigsaw, but
I really want super straight cuts and each to
be the same. Not sure if the jigsaw is the right
tool for this job.
I looked at the Kerfmaker - nice tool, but am
barely able to afford to buy MDF these days
then another tool. Besides, it looks like
it's better for a tablesaw, then a router.
Hope that helps.
Based on your description, this is a classic table saw job.
Do you have a decent T/S?
If so, do you also have a dado set?
Just curious, why do you want the ply pieces to interlock?
What is the ultimate purpose of this structure?
Will await your response.
Based on your inputs, here is how I would attack this project.
Start with a 48" x 97" x 12mm (4 ply) sheet of CDX plywood and cross
cut a 48" x 48-1/4" piece for the top. with a guide and a circular
Use a router and a straight edge to clean up cut edge for a 48" x 48"
Cross cut the remaining ply into 24" x 48+" pieces.
Rip 5 pieces, 4" x 48+" from each 24" x 48+" pieces.
Final cross cut 2 pieces, 4" x 48".
Final cross cut 8 pieces, 4" x 47".
Set aside the 48" and 2 of the 47" pieces for the outside box frame.
Temporally screw the remaining 6 pieces into groups of 3 pieces.
Set up your dado to cut 2" high x 12mm wide dado. (Make a new zero
Set up a box joint jig using your miter gage to set the correct
spacing between dadoes.
Again set up a zero clearance insert on the box joint jig using some
scrap 1/4" material.
All the wooden parts are now complete.
When assembled, you will have a 4 x 4 box with 16, 1 x 1 boxes inside.
You indicate you may want to take box apart, so time for a trip to the
Get 2 pcs, 1-1/4" x 1-1/4" x 1/16" x 96" aluminum angle and a throw
away table saw blade to cut the aluminum angle.
Also the following hardware:
100 pcs, 1/4"-20 x 1", Flat hd bolts
100 pcs, 1/4"-20 x 1", Hex hd bolts
100 pcs, 1/4"-20 x 1", Hex nuts
100 pcs, 1/4" Flat washers
Using aluminum cutting blade, cut angle into 4" pieces (32 minimum).
Next drill 9/32" holes thru flanges of the angles.
Each corner piece requires 2 holes in each flange.
All interior and cover angles require 2 holes in one flange, 1 hole in
the other flange.
That's a lot of bolts and nuts, but it insures a strong box that can
be assembled or disassembled as needed.
Depending on final use and the amount of work you have invested, you
may want to upgrade the plywood from CDX.
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