Hello and welcome back to Switch & Lever! Long time viewers of this channel are probably
aware of my love for laser cutters, but until now there hasn't really been any video solely
focusing on its use so I figured it was time for a change. In this video we'll cover one of the most
basic principles of laser cutting, but one that beginners often struggle to get right,
making a custom box with properly fitting boxjoints. So let's get going and shoot some lasers! Well...I may been a little overeager there,
let's turn off the laser cutter and sit down in front of the computer first and talk a
little about box joints! Box joints are probably the second simplest
joint in woodworking, short of the simple buttjoint. Unsurprisingly it gets its name because it's
a very common and strong joint used in boxes. Basically it consists of interlocking fingers
on two pieces of wood that fit well into each other. In most boxes you find you'll find fairly
small fingers, but they can definitely be made wider, at the expense of less glue surface
and a weaker box construction. Unlike a dovetail joint the joint is not self
interlocking, and definitely requires glue to be held tight, but also unlike a dovetail
joint everything is cut through the board at a 90 degree angle making construction much
easier. They're commonly made on a jig on a table
saw, but as you probably guessed by now that this is where our trusty laser cutter comes
in! Designing a box joint is actually really simple. You obviously need to know the dimensions
of the box you want to make, either the inside dimensions and add the thickness of material
you have to get the final box size, or directly by the outer dimensions of the box. Here is the really good news for those of
you who don't want to bother either with CAD or manually drawing your vectors for laser
cutting: there are box generators online into which you can feed in your dimensions and
it will spit out a file which you can take to your lasercutter. However, the downside is that this will get
you only the most basic of boxes, which may be fine for you, but if you want to make a
custom box it's better to draw it from scratch. What I've done here, which will be more apparent
later in the video, is add two black rectangles on each piece which will be etched partway
through the plywood I'm using to create two grooves into which the pieces to fit the bottom
of the box as well as a sliding lid will go. This obviously requires a bit of extra set
up time in the laser cutter cutting out test pieces to make sure you get a deep enough
engraving for your grooves. Now, here comes the trick which I hinted of
in the video title. The laser cutter has what is called a kerf. What is a kerf? A kerf is basically the amount of material
that is removed in a cut. Imagine a table saw, the amount of material
that the saw removes when cutting is the kerf. A laser cutter, even though the laser beam
is very narrow, also has a kerf even if it's not as apparent as on a table saw. The width of this kerf varies from laser cutter
to laser cutter, and from material to material, so you have to cut a bunch of test pieces
to figure this out for yourself. Simply you can cut a square of a known dimension
and measure it with calipers and note down the difference. If we look at this boxjoint test piece it
was cut exactly on the line as drawn, and as we can easily see the pieces do not fit
together well, and they just fall apart if we let go of them. If we were to glue together these it would
probably work, but it would be a very sloppy glue joint, and the glue would have to fill
in a lot of empty space which wood glue is not really designed to do. So, how do we solve that? Once you've finished designing your box you
need to simply offset all the cutting lines by the width of the kerf. In my case the kerf ended up being 0.2mm wide,
so I offset the cut line by 0.2mm. Once cut, the pieces should have a snug fit. Looking at this second test piece we can also
confirm that is the case. It fits, it is snug, but it holds together
quite well even when we let go of the pieces. This is exactly what we want! But wait! There is more! The length of the fingers can also play a
big role in how your box will look like. If we cut the length of the fingers to the
thickness of our material, in this case 4mm, and then glue them together the burnt ends
will be visible in the final joint. You may like this, in which case you can ignore
the following step, personally I think it just makes it look like every other laser
cut box, and I would like to avoid it. Thankfully it's very simple, just make the
fingers longer so they stick out further. Once glued together they will sit proud of
the surface and can easily be sanded down flush, and with that the burnt ends are gone! So, I think at this point we have everything
down pat! Let's cut out our actual box! [laser cutting music] While laser cutters do really well on wood
and plastics I would not recommend cutting circuit boards on them. If you have a need for custom made circuit
boards of high professional quality, why not head on over to PCBway instead! PCBway has been a long supporter of this channel
by now, and I am very pleased with the quality of their circuit boards. Ordering could not be easier, upload your
gerbers and set up your order. With ten PCBs starting for as low as $5 what
do you have to lose? Head on over to PCBway today! So, now with all our pieces cut out it's simply
a matter of applying what we have learned so far. Depending on your wood, and especially how
dirty it is to laser, you will have to prepare the pieces before gluing. Unfortunately my plywood is very dirty, and
covered in soot. Wiping off what you can, and giving any surfaces
that will be on the inside of the box a light sanding is definitely a good idea. The grooves we etched also need to be cleaned
out a little bit. Scraping them out with a chisel works well
to smooth them out a bit and get rid off the excess soot. This will both help with glue adhesion when
we assemble, as well as with smoother operation of the lid. Do keep in mind that the fingers of the boxjoint
are all reasonably fragile at this state, so don't go too ham on your standing. Treat them with care and kindness and your
sensitivity will be rewarded. Before gluing make sure you dry fit the pieces
to make sure everything fits properly. Don't just push the joint together if it's
tight, remember what I said about the fragile fingers. Work it slowly together wiggling it from side
to side if necessary if it is a little tight. If there are any overly tight spots you can
always sand or scrape a little with a chisel to make the fit a bit better. Remember also not to add too much glue, as
it will just make a mess. Focus on getting glue into the joint with
a minimal squeezeout when you push the joint together. I assembled the box in two L-shaped sections,
making sure each secton was square when glued together. Before the two sections were brought together,
with the bottom glued in between the box was again dry fit and the edges of the bottom
part sanded lightly to ensure a good proper fit and that all the joints would come together
properly. After that it's just a matter of taking apart
and gluing together again. I think you've gotten the idea by now! Once all the glue is properly dry we're almost
done. All that's left is sanding down the little
nubs that's sitting proud of the surfaces. While I'm using a belt sander here to knock
down most of them you could definitely do the same with just a sanding block. Of course, while you have the sanding paper
out you could just go ahead and sand down all the outside surfaces to smooth them out,
and knock down the sharp edges a bit as well. Just look at those sweet boxjoints! Ain't that just the most beautiful thing you've
ever seen? At this point we could truly be done, but
what's the fun in that? Any job worth doing is worth overdoing! So let's also give this thing a nice coat
of varnish. It's not really required for a good box but
varnishing to give it a smooth surface will definitely kick it up an extra notch. If you do varnish it though take care not
to get varnish into the groove to avoid gumming it up. For this same reason I masked off the edges
of the lid so there is no scraping of varnish into the groove when opening and closing the
lid! That's about all there is! You now have a professional looking box with
just a few steps of the laser cutter. Not only that, but if you followed all the
steps properly you may find that the box is actually magic! I sincerely hope you enjoyed this video! Please do leave a comment below, like, subscribe,
howl my name at the moon during a clear winter night, you know all the steps by now! Remember that there are more regular updates
over on instagram, including sneak peeks of coming videos! Until next time!
