How to join
4x4 Lumber
How To CUT CROSSLAPS (In Thick Lumber)
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hey everybody I'm Ethan James with the
honest carpenter comm in this video I'm
going to show you how to make cross lap
joints and thick lumber like these
pieces of 4x4 post cross laps as you can
see are an interlocking joint made by
cutting halfway through the depth of two
pieces of lumber so they can overlap one
another on an even plane in thinner
lumber these joints can be made with a
router but in thicker lumber you need a
different approach so I'm gonna show
that in a moment but first I'll mention
that I originally made cross laps like
these when I was building a wedding
Arbor for a friend you can see the Arbor
here I made it out of 4x4 cedar posts
and I'll put those decorative overhangs
and lift cuts on the ends came out
looking really great but since it was
for a wedding service I also had to be
able to break it down and set it up very
quickly so I had to engineer a few
things with the project just to make
that possible I actually wrote a short
how-to ebook about the project because
people seem to like it so much that
ebook is available on my website and on
Amazon so if you're interested in
recreating this build think about
grabbing a copy it's just a few bucks
and it has a lot of other information
about lumber selection and cutting
techniques so you get a lot out of it
but getting on with our current topic
all you really need to make deep cross
slabs like these are a square a circular
saw and a chisel to begin the process I
just decide where I want my cross lap to
sit on the pieces of lumber in this case
it's about 6 inches in from the end I
use a speed square to mark a straight
perpendicular line at this point but
instead of trying to use measurements to
layout the second line I actually like
to use the piece of stock that I'm going
to be joining I line it up by eye with
my first pencil mark then use the other
side as a guide to make my second pencil
mark and it helps to site down on the
piece from above when you do this and
you should scribe your line just a
little bit wide of the 4x4 edge these
are the perimeters of our cross lap but
now we need to set our depth so here I
do use my tape measure to find the true
center of the lumber stock which is
about an inch and 3/4 in this case and I
put a little dash right there I can then
use this line to set my circular saw
blade by eye locking it in place at this
exact depth with all these marks set
we're ready to cut
I like to make my perimeter cuts first
lining up the point of my blade tooth
with the pencil line I use my speed
square as a guide for my saw I can just
push the edge of the sole plate up
against the edge of the square this
keeps the saw perpendicular to the stock
without that much effort and I can run
my cut straight through confidently if
possible try to split your pencil mark
right up the centre takes a lot of
precision but it can be done when the
first perimeter cut is done just repeat
the same process for the other one a
quick check with the other piece of
stock shows that it will fit cleanly
inside the perimeter cuts that you've
made so now we have to remove all the
wood that's actually between these two
cuts to do this I usually clamp the
stock piece to a table for stability and
just to free up both my hands without
chaining my blade depth at all I
carefully Ben begin making a series of
cut passes through the stock spacing the
cuts about an eighth of an inch apart I
don't even use a speed square to do this
which is why my cuts start to become a
little bit angled but it doesn't really
matter the point is that I'm removing
much of the wood quickly with a strong
power tool just be careful doing it
though keep your clothing out of the way
and try to stay in to the side of your
saw a little bit in case it kicks back
it's easy to lose lose focus when you
make a bunch of repetitive cuts so pay
attention don't feel the need to rush
when all the cuts were made you have
this row of Filat strip's standing up in
place and because I've made the cuts
across the grain these strips have
almost no lateral strength to them at
all which means they can they can be
broken out with little effort I
sometimes do this with a hammer or I
just wedge a screwdriver in the last
slot and crank it over sideways and
it'll cause like a domino effect and the
pieces will generally just come out in
one big clump you can do a little bit
more cleaning by prying the filip bases
that are still standing up but to get a
smooth floor to the joint the best thing
to do is just switch switch over to a
sharp 1 inch chisel with the bevel
facing upwards
I begin to push the chisel to the uneven
material in a flat raising motion it can
help to push down on the chisel with two
fingers also as you do this to create a
bit more pressure and you can flip the
piece entirely to approach high points
from the other side as well cutting back
towards the centre to be honest I've
never been that great with a chew
carpenters don't use them nearly as much
as woodworkers do but this methods
pretty forgiving and you can use a
combination square to try to cite high
points or unevenness in the floor of the
cut where you may need to do just a
little bit more work you can also test
your cross lat fit by passing a full
piece of stock through it
if it feels too tight use your speed
square to make a salt pass along one of
the cheeks of the cut widening that side
out just a bit when the first cross lap
is clean just repeat all the steps with
the second piece measuring marks for
layout set your perimeter cuts make your
free hand passes carefully and then
break out the excess material and clean
the floor when Beau's cross laps are
done you get the satisfaction of sliding
the two pieces together for a quick test
fit if their tops don't quite line up
feel free to do a little more chisel
work on the floors at any high points
but once they do line up you're all set
if you're making structural cross laps
you can permanently join these pieces
with fasteners or adhesives or if you're
making something mobile like my arbor
use the threaded rod technique from my
ebook worked out really well and it made
it very easy to get the pieces together
and back apart again in a short amount
of time so that's how you make cross
laps and thick lumber if you have any
questions feel free to ask me down in
the comments I always try to answer them
and as always if you enjoyed the video
please hit like and subscribe below I'm
Ethan James with the honest carpenter
comm thanks for watching everybody
