4 Steps to Easy and Strong Miter Joints | Woodworking Tips

Today I'm going to show you how to make
your miter joint stronger and easier to assemble using splines. he two basic
miters are corner miters like you'd see on a picture frame or edged miters like
you'd see on a mitered box or on a waterfall edge. today we're talking about
edge miters but I do have a video on corner miters three ways to make picture
frames you can go check that out too now I'm trying to other methods but
using the table saw and tilting the blade works best for me for edge miters
and be sure to unplug your saw before touching the blade you want to tilt that
saw blade to 45 degrees and check it with a good carpenter square or drafting
triangle just make sure you put the square between the teeth of the blade so
they aren't hitting the carbide tips and skewing the measurement another way is
to use one of these little digital angle cubes basically it is a level and you
can put it on your table saw base zero it out put it on your blade it has
magnets and then tilt it until you get to the 45-degree angle I actually prefer
just using the square but you can use these and you can probably get it really
close and maybe yours is a little bit more accurate than mine make a test cut
on your setup and then use a ninety degree square to check it now hold your
parts tight to the square and slide them together at the joint if the outside
corner hits and there's a gap at the base then your blade is tilted too much
in your past 45 degrees but if you have a gap at the outside corner in the base
is touching then you need to tilt the blade a little more to get to 45 degrees
you can make any minor adjustments here and then go ahead and cut your miters on
the parts now I use a dedicated miter sled which is my old crosscut sled for
miters and I take off the front fence if I need to for wider panels you could
also use the miter gauge for shorter miter cuts or use the fence for long
liners just make sure whatever you use is properly squared to the blade now I'm
gonna make a little mitered box for this example and I'm also going to show you
some clips from my modern desk if you want a waterfall edge with continuous
grain flowing from the top to the sides you want to mark your parts and plan for
those cuts so I marked up this little test box to designate the bottom left
side top and right side now I'm not gonna go super deep onto the waterfall
edge portion here just make sure you plan everything out before you make your
cuts the biggest tip I can give you on this is just to remove as little wood as
possible between the top and the sides so
the grain lines will connect and look seamless and while you're making your
cuts make sure you also run a few extra scrap pieces from the same material that
you can use for setup later now that you've got some good clean miters now we
can go to cut the splines the beauty is you use the same 45 degrees set up that
you did just a minute ago we'll make the spline cuts in two passes
and for the first one I lower the blade to about five eighths of an inch at the
highest part of the blade then I measured another five eighths of an inch
in from one of the mitered setup pieces and I marked a line there I used this to
set the fence what I'm trying to do is get the edge of the blade to hit on that
line now keeping the spline towards the base is going to give you more material
to work with here to run the test piece through at this setting and check to
make sure the curve is at least a quarter inch deep and that it's more
than 1/8 of an inch away from that inside corner so you don't blow through
it if it's okay then go ahead and run all your pieces through at this setting
as well as your test parts for the second cut you're going to need to widen
the groove to match the thickness of your spline material you also need to
lower the blade a little bit so that you can match the flat bottom of the first
cut you'll see what I mean here later just start off by lowering it about a
quarter of a turn now the fit that I go for on the spline is just enough to go
in there easily but then it will hold the piece in if you give it a little
wiggle and if you really knock it out it might come out there you go but what I
wanted to do is go in nice and smooth because you don't want it to be too
tight that'll hem you up in assembly and if it's too loose then it's gonna be a
little bit too much wobble so just enough to go in you can also see the
second cut was a bit deeper than the first one and I don't get that flat
bottom that I was talking about and this isn't a big deal if your edge banding
the face but to fix this you can adjust the blade up or down to make it flat but
you're still going to have those little ears sticking up unless you're using a
flat bottom blade and once you've got that perfect fit you can run the rest of
your parts through at this setting and next we need to size the splines
now if the splines won't be exposed you can leave them a little under sized and
width to make sure that they don't keep the joints from going together I dry fit
the joint together and I measured the gap and then I used my quarter inch
plywood to cut just under that measurement which was about a half an
inch I also milled up some walnuts I want to
show you an example of contrasting splines now if you do this you'll want
the splines to be matched almost exactly so you can avoid any gaps but I've got a
better solution that I'm going to show you during assembly
one other thing I've noticed is using quarter-inch plywood with the grain
running the width of the spline versus the length of it is actually better it's
because the inner core runs the opposite direction of the veneer and the cross
grain core tends to bend and bow more like you see it here alright let's get
into some assembly tips and tricks now not only do the splines make the joint
stronger they also make it easier to assemble especially on larger projects
like with my modern desk now in smaller pieces I would typically put tape across
the outside of the miters and fold up the assembly and tape it closed but with
something like the modern desk that would have been very difficult because
of the size so using the splines you can easily do a dry fit since they're gonna
hold the sides in place vertically and let you put the top on without needing
clamps or tape now this helped a ton on the modern desk because it was such a
large piece to manage so go ahead and do a dry fit now and look at your assembly
and see if you have any gaps or any interference at all before you get into
glue up I mark the splines to size on that box as well and then I cut them to
length before assembly now for the glue up I would recommend using a slow
setting glue with an open time of about 10 minutes or more a standard glue might
only have 5-minute open time but an exterior glue or a specific slow setting
glue could be 20 or 30 minutes and you might want that extra time and don't go
squeezing the glue into the spline groove you want to avoid excess glue
squeeze-out so give the spline a thin coating of
glue and then just push it into place and if you've got a tight fitting joint
and the spline you don't really need a ton of glue anyway I like to use a web
plant to get everything pulled tight here now they have clamping pads that
wrap around the corners and they put pressure on both sides without crushing
that corner and you can get one of these from wood craft the sponsor today's
video I'm gonna leave a link below to a few different options on the wood craft
website along with the other items that I used in this build if you can get a
ton of other different woodworking supplies for them so go ahead and check
them out thanks for craft and if you don't have a web clamp a ratchet strap
makes a good stand-in or actually an additional helper on large pieces I also
typically add more clamps to pull gaps tight where they're
needed as well now there are definitely other ways to clamp minor so go ahead
and let me know in the comments what your favorite method is now after the
glue up you can remove any glue squeeze-out and break the edges of your
mitered corners being careful not to blow through that plywood veneer
alright this thing is all good now I do have a few little gaps on the edges I
left those gaps just for you guys because I want to show you how to close
them up actually not so this walnut I tried to get it super tight when I was
using that walnut spline so that I wouldn't have many gaps when I realized
though as I was gluing it up is I use plywood on these bakwin's and all you
have to do is use the plywood and make it just a little bit of a loose fit so
it's nice and easy to assemble so you don't have this kind of issue and leave
it about a half inch to three quarters of an inch shy of the end now I can go
back in and use a contrasting walnut plug and it's gonna be just a little
spline in there and it's just gonna be for show so you get all of the strength
from that plywood and then just cap it off with the walnut and you don't have
to worry about getting a perfect fit on that walnut while you're climbing it up
but if you do get some gaps let me show you how you can fix that real fast with
just using a screwdriver now use the screwdriver and run it along both sides
of the joint pulling it towards the corner and basically what you're doing
here is crushing that open gap shut now with plywood you do have to be a little
bit careful so you don't break off that veneer now it's not gonna seal up huge
gaps but it does work well on small hairline gaps if you have gaps left over
you can fill them with sawdust and glue if you wanna see how I strengthened
corner miter joints you can check out my picture frame video right here I go into
a ton detail let me know what you think about these tips videos and what else
you would like to see me talk about but I'll get you on that next video and
we'll build something awesome together

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