BYO: The Pliage

Bones

Ok, thanks for all the replies/info.

Wish me luck!

Craig Bumgarner

Friday afternoons are slow at the DB forum, so I thought I would "liven things up" with an update to the pliage thread. I have a new method: bend the jointed top dry with the clamping setup shown earlier in this thread using heat supplied by a 2" x 18" silicon heat blanket. Using the blanket, I heat the pliage line to 300 F, clamp down on the top & blanket, hold at 300 degrees for 5 minutes, then turn off the heat and then let it cool to ambient while still clamped up, about an hour. Perfect pliage. Bending dry means no hydration issues on the top. Joining the top before bending is much easier than joining halves that have bends in them. The heat blanket keeps the heat right where you need it and holds it long enough to cook the bend.

Here is a picture of the first one I used this method on a month ago. I did it with the braces attached (long story :oops: ). This morning I did a 4mm cedar top with no bracing. Not having braces in the way obviously works better. This is by far the best approach for making the pliage I have used so far. Takes less than five minutes to set up, five minutes to cook it, eat lunch while cooling, brace it this afternoon. More about the silicon heat blanket below.



The silicon heat blanket, the orange thing in the picture, is part of a system sold by Luthier's Mercantile in CA. The system is composed of a heat blanket which is about 1mm thick, a temperature controller and a temp sensing probe. Blankets come in a variety of sizes and shapes for bending parts and heating glue joints for removal. The most common use is for side bending. The guitar side is sandwiched between a 5" x 32" blanket and a couple pieces of thin spring steel slats and bent with clamps to a mold. The blanket I have is for heating fingerboards for removal which is what I originally bought it for, but it is also the perfect shape for heating for the pliage bend. The heat is concentrated to an inch either side of the bend line and the controller maintains temperature within 1 degree . The blanket heats up quite fast and seems reasonably robust. Doesn't seem to mind the pressures.

This method is so simple, quick and damn near fool proof. Not a hint of cracking the top. I was worried at first that the heat might disturb the glue line, but no hint of this either. The investment in the heat blanket & controller is about $250 which is too much if you are just building one, but I find I use mine for a variety of things besides pliages.

Anyhow...... Have a nice weekend everyone.

CB

Craig Bumgarner

Oh, another funny thing. A French speaking guitar maker pointed out to me recently:

"Do not forget the accent on the bombé word. Bombé is a shape, Bombe is.. just a bomb"

8)

Jeff Moore

Craig
Your post on bending are a kick. I don't build, but am interested in the sonic results.
A 250 $ investment towards a largely foolproof pliage seems pretty modest.
I bought a Lebreton recently. It has the most noticeable pliage I've seen. It sounds better than anything I've heard too. There's a lot more than a pliage to account for sound of course.
Thanks for the explanations.
Do you build consignments or mostly for yourself? Is there a brand name for your work?

Bones

Craig, if you join the top first does the heat loosen the glue joint? What kind of glue are you using?

Thanks for the info!

Craig Bumgarner

Jeff: Glad you enjoy this little bit of trivia. The pliage seems to be kind of mystery and I've enjoyed learning about it. Most of my luthier chat happens on luthier based sites, but some of this Selmer specific stuff I like to mention here because we are the only ones much interested in it.

As far as I can figure, the pliage is really just a way of returning the top to the sides as the tail block without pulling (pushing?) the arch out of the braces at the bridge. The top bends easily across with grain, but with the grain is another matter. The top edge of the sides on most Selmer style guitars are flat or close to it. Without the pliage, the top flattens out the arch when the lower part is pulled down to the block. By pre-bending the top, this stiffness of the top along the grain is by passed. Di Mauro solved this problem by raising the sides up at the tail block, so the top arch is more cylindrical than spherical. But it if one wants straight sides AND a lot of arch, the pliage is a bit of a necessity.

Sonically, my take is the pliage affords a substantial arch which structurally allows for a lighter top assembly which is more responsive as a result. There's more than one way to build an arch of course, but the reason for the arch is a lighten up the top assembly.

Regards my guitar building, I've been building for about five years now after having built guitars in the 1970s, including a short stint as an apprentice to a well know luthier in New Hampshire. I have not been taking consignments as I am not confident I could give someone everything they might be looking for in a guitar. At this point, I would rather build what I like to build and then offer it up if it turns out well. If someone likes it great, if not, on to the next! I'm afraid I don't have a web site, though I have been considering a blog of some sort as a way of getting some pictures out there without dropping them all here. I'm trying to finish a guitar to bring to Django in June right now, so maybe after that.

Bones: I was worried about upsetting the glue joint, but my experience elsewhere was that unless the heat was prolonged and force applied, it was unlikely to come apart. By not using any water/steam and by applying heat to only a 2" long section of the top joint, I hoped it would be okay. This works out to be the case. My only concession to protecting the joint is a couple pieces of masking tape across the top joint before placing the heat blanket. Oh, I use Titebond glue (original formula) for this joint.

This method, which I came up with in order to bend a top which was already joined and braced (I didn't think I needed a pliage.... little did I know :oops: , funny, I learned more about the pliage by not using it), was really a revelation to me in that it allows the top to be jointed and glued up flat which is much easier. It also means I'm bending only one piece instead of two and there is no problem with one being bent a little more or less than the other. Bending dry is a big improvement too as I was always getting a little warping from the humidification of the wood.

Craig

Bones

Ok, so do you now bend it all the way across? Not the tapered bend?

thanks

Craig Bumgarner

Bones wrote:

Ok, so do you now bend it all the way across? Not the tapered bend?

Right. In hind sight, I think the tapered bend is a bit of a red herring. The bend goes flat on the edges when glued to the sides anyway, so it really doesn't matter much. My previous method allowed for a tapered bend so I figured what the heck. The new method does not, and I'm certainly not going back.

Bones

Can you post some pics of the bending jig without the top so I can see how it is made?

thanks

Craig Bumgarner

Bones wrote:

Can you post some pics of the bending jig without the top so I can see how it is made?

Bones, it is not really a jig per se, just a couple blocks of wood and some clamps, so a picture would not show much. The sketch I posted in the first entry on this thread shows it about a good as I know how. Take a look and feel free to ask.