Greetings and felicitations. Today, March 14, 2006, we are going to make a bamboo-backed ipe bow. Isn't that exciting? But why ipe, you ask? Well, there's a few things you ought to know about ipe.
First, you need to know how to pronounce it. Ipe is pronounced "EE-pay." Can you say EE-pay? I knew you could.
Second, you need to know what ipe is. Ipe is a Brazilian walnut. Okay, you didn't really need to know that.
Third, you need to know some properties of ipe. There's good properties and there's bad. We're mostly interested in the good properties, but we ought to be aware of the bad.
The bad thing about ipe is that a lot of people have an adverse reaction to it. Mostly, it causes some people to itch. Thankfully it doesn't bother me a bit. You ought to do some reading on it some time. There's plenty of information on the internet.
The good thing about ipe is that (1) the grain is almost always straight, (2) it rarely has any knots, (3) it's very stiff, (4) it's very dense, and (5) it's quite resistant to decay.
Numbers 1 and 2 are desirable for any kind of bow wood, but what makes ipe unique is 3 and 4. 3 is especially unique about ipe. Ipe is so stiff that the dimensions will be quite unlike most wood bows you make. The limbs will be much thinner. The cool thing about that is that even though the wood is very dense and heavy, the limbs actually end up being lighter than usual. And since they are also thinner, the bow ends up being faster than usual. Ipe backed with bamboo makes a deadly combination.
Number 5 is a clue to sources for ipe. You need not only search the hardwood stores. You can also search for decking. Ipe is used in decking because it's so resistant to decay. I've even read that you can use it without putting a finish on it, and it'll last through all types of weather. I don't know how true that is.
You also need to know how to pick out a good piece of ipe. Besides straight grain, which is a given with any kind of bow wood, you want the ipe to be nice and dark. I've made more bamboo-backed ipe bows than any other kind of bow (it being my favourite), and I have discovered that the darker it is the better. The lighter coloured ipe sometimes frets (i.e. gets compression fractures) on the belly if you don't tiller it just right. I've never had any problems with the darker coloured stuff. Here's an example of what I'm talking about:
Ipe that looks like the bow on the top might give you problems. You want to find ipe that looks like the bow on the bottom. Except that it won't be a bow when you find it.
Oh, there's one more thing you ought to know about ipe. Ipe is one of those oily woods where hardly any finish will dry on it. I use Deft lacquer, because it works beautifully. It'll dry within 20 minutes. You can put a couple of coats of Deft on it, and then any finish you want on top of that. Or you can just finish the whole thing in Deft. But I'm getting ahead of myself.
Like ipe, bamboo also has both good and evil. The evil of bamboo is that the splinters are horrendous. They're tiny, hard to see, and annoying. Also, bamboo is bad on the skin and murder on the lungs. Please please please use a respirator when working with bamboo. It's not quite as bad as fiberglass, but it's pretty nasty.
It does smell like hay, though, so if you're into that, then that's a good thing. The other good thing about bamboo is that the grain is always straight. Also, bamboo is unusually strong in tensil strength. It's so strong, in fact, that some people discourage using it with some woods, because it tends to overpower those woods. Bamboo works great with things like ipe, though, since ipe is so strong.
Good heavens! Isn't that clear enough by now?
There's something I wanted to add to this build along but wasn't sure where to put it. It's important, so I'm just going to stick it right here. We can't very well have a first page without pictures anyway, can we?
I'm going to be gluing a riser on the belly of the bow. A lot of people have had problems with this because it can cause the handle to pop off. You see, there's a transition between the flexing limb and the stiff handle, and that transition is the fade. If you have the limb moving all the way up to the fade, and then you have the entire fade consisting of the riser wood, then the riser wood is going to have to absorb some of that flex. It will put a lot of stress on the glue joint. If the limb wants to bend, the riser wants to stay stiff, and there's stress on the glue joint, the riser could pop off.
There are three ways to avoid that. One way is to glue a thin tapered piece of wood between the bamboo and the belly wood. It must be longer than the riser. That will cause the transition period to happen in the limb and take the stress off the glue joint on the riser wood.
A second way is to make a tri-lam bow where you have a bamboo backing, some type of core (maybe ipe), and then a belly lam (of bamboo, ipe, or whatever). If you run the belly lam up the fades, there will be no glue joint to be under pressure since most of the compression forces happen on the surface of the belly along the continuous lam.
The third way, which is the way I usually do it, is to have the fade run into the belly wood. That way, the transition just about stops before it gets to the glue joint.