Marc - Today I'm going to introduce you to one of my all-time favorite
woodworking techniques, bent wood lamination. (upbeat music) If you like to build furniture that has lots of curves
and curved components, you're eventually going
to confront a situation where a solid piece of wood
just isn't going to cut it. For instance, this rocker
for a sculpted rocker. Imagine doing this out of
a solid piece of stock. You'd have a lot of end-grain,
short-grain situations, and you'd need a very large
piece of wood to do it. So we have to learn how
to bend wood to our will. There's a couple different
ways you can do it. Number one is steam bending, and that basically involves
putting a work piece into a steam chamber, and then after the wood fibers have sort
of softened to some extent, you take it out, quickly
get it into a form, and clamp it down. It's kind of like perming
your hair, in a way. You sort of put the water in and reset it in its new shape. The lucky thing is I don't
actually need a perm. I have naturally curly hair. Now, steam bending is great, but I don't really have a set up for that. What I do most of the time is
called bent wood lamination. That involves taking a
whole series of thin strips, and then bending them
to the shape that I want with adhesive between each layer. Now if this were a solid piece of stock I certainly would not be able to bend it. But because it consists of about
five different layers here, I could easily bend this
to whatever curve I need, of course, within reason. Right? So if we're going to bending this stuff, we need a form of the proper
shape that we're going for. When I first learned about wood bending from my mentor, David Marks, I was always amazed and a little amused, by how much effort he
put into the form itself. But over the years I've realized there's a good reason for that, because when you're bending wood you can't take any chances. You have a lot of time
and effort and money invested in that material,
so you can't mess it up. Let me show you how you build
a good-quality bending form. First we'll need to transfer our pattern to a piece of 3/4" plywood
using spray adhesive. Cut along the pattern
line at the band saw. Using a rasp or spoke
shave, fare the curve so that it's nice and smooth
with no major hills or valleys, and finish it off with a
flexible sanding strip. Now we need to make an accurate negative of the curve that we just created. Position the board onto a new piece of 3/4" plywood. Clamp it in place and set a scribe to the thickness of your lamination, which for me is 1-1/4". I like to line my forms with 1/8" cork, so that's included in my number. Keeping the scribe
perpendicular to the curve, run it along the length. Now we can cut out the
negative part of our form. Use the pencil line as a guide, and try to stay as true to
that pencil line as possible. All right, so here are
the two starter pieces. We've got our base of the bending form, and this piece will go to make our calls. Essentially it's the
negative, if you will. But the thing is, you might
be confused at this point as to why we had to mark in 1-1/4". It comes down to the radius of the circle. If we start with this piece, this is the primary one, right? This is a 42" radius. Think of this as if it
were a giant circle. Now if we go in 1-1/4" from there, we no longer have a 42" radius. We have 42 minus 1-1/4". It's a smaller circle. Right? If we made this negative piece match up perfectly to this profile, then it would be also a 42" radius, which would not give us the
proper clamping pressure and support where we need it when we actually are clamping 1-1/4" away from this shape. So this is why we measure out 1-1/4". Now we have a smaller radius circle on this piece for the negative. That's going to give us the
proper clamping pressure. Both parts of the form need to be thicker, so we'll glue each of them
to another piece of plywood. (light music) Once the glue is dry, the excess
is cut off at the band saw, leaving no more than 1/8" proud. Then the second piece of ply
is flushed up to the first using a flush trim bit. If your lamination is really wide, you can keep adding
subsequent layers of plywood using this method. I cut some scrap cork into strips and glue those to each
face of our bending form. Keep in mind that this cork
is completely optional, but when it comes to bending forms, it can be helpful to have
a semi-flexible material between the form itself
and the work piece, as it helps distribute clamping pressure, and makes up for
imperfections in the form. Both sides of the press
are covered completely in packing tape to help
protect it from glue. On the primary part of the bending form, I'll attach eight evenly spaced cleats. These cleats will raise the entire form up off the work surface, making it easier to clamp. Here's how the pieces of
the form will come together. With the form made, now
we need to take our stock and cut some laminates. How thick to you cut these pieces? Well, it kind of depends. Sometimes you have to think
about the wood species. Some woods bend easier than others. And you have to think about the curve you're forcing it to bend into. The more severe the curve, the thinner the pieces have to be. You're going to be somewhere
between 1/8" and 1/4", whatever the project will tolerate. For me, usually I go a
little bit over 1/8", maybe up to 3/16", and that's usually kind of a happy medium to aim for. But it usually does require a
little bit of experimentation. All right, so let's slice these up. The lamination strips
are cut to about 3/16". I like to use a feather board to help keep the material tight against the fence. After each cut I take a
very light cleanup pass at the jointer before
cutting the next slice. This ensures that each strip
is of a consistent thickness and has at least one clean face. (light music) Once your strips are all cut, you'll want to smooth them out and bring them to final thickness. I use a drum sander, but you can also use a planer and a shop-made sled. (light music) You can also use your table
saw to cut the strips, where you could very well
have a glue-ready surface right off the saw. (light music) Once you have your laminates ready, do a quick dry run with your bending form. Now when it comes to the
adhesive for bent lamination, you've got a lot of options. Let me show you a few right here. First I've got Unibond 800. This is DAP Weldwood. And here's some West System's epoxy. Now all three of these are
great for bent lamination. They give you a nice rigid glue line. But the problem is, they're sort of on the other end of the
scale in terms of safety. I don't really like
formaldehyde-containing glues if I can avoid them. Epoxy is super expensive, and you kind of develop a sensitivity to
it the more you use it. So if I can avoid it, I'd like to. And there are other options. Many folks have no problem using standard PVA glues in bent laminations. What I have here is Titebond Extend. This gives me the extra
working time that I need, but I have the normal
safety that I'm used to with the typical glue
that I have in the shop. Ultimately, you've got
to make the right choice for you and your shop
and what sort of safety you'll tolerate, what materials
you want to work with. For me, I'm going with
the Titebond Extend. Keep in mind, there's a
lot of new formulations of PVA glues out there that are intended for laminations like this, so they've kind of tweaked the properties to be a little bit more
appropriate for this work. Either way, whatever you choose, get your jig ready, because
we've got to work pretty fast. Each strip receives glue
as we build the stack. A glue roller is incredibly helpful here, since the clock is ticking. (light music) The stack is then placed into the form and I'll begin clamping at the center and working my way out from there. (light music) I'll flip the form up on end and apply a few more clamps to the other side, and that helps balance out
that clamping pressure. All right, that is looking pretty good. I've got plenty of squeeze out. You know, a lot of times
we avoid squeeze out, but when it comes to a bent lamination, I want to see it. Squeeze out tells me I got
glue between each layer, which is critical for this
thing to not fall apart and delaminate over time. All right, it's the next morning, and I've removed the clamps. This piece slides off easy enough. Let's see what's going on here. It's probably going to
be a little bit stuck. So grab your dead blow and just knock things around just a little bit. That should be all it takes. Wow! That is awesome. So as you can see, once you
have all these techniques down, you're really only limited
by your imagination. I hope you give bent
wood lamination a shot. Let me know how it works out for you. (upbeat music)
