fitting binding to profiled sides

[Kary Karahadian]

I'm having an ongoing love/hate relationship with the wooden bindings I use. Due to the radius, which is much more pronounced at 15' on my backs than my tops, the binding is asked to bend in all three planes of space, not just the two the follows the outline of the guitar. I like to start fitting the binding at the waist, working my way first to the tail and then up to the neck. due to the radius, the binding tends to bow out around the apex of the bouts (hope this is making sense). If the sides were not profiled but flat, this wouldn't be an issue. Other than strong binding tape, does anyone feel the need to deal with this inaccurancy, and if so how?

kary

[Barry Daniels]

Sometimes, I bend the binding sideways right at the waist. The bend ends up around 5 degrees or so, and that seems to help.

[Kary Karahadian]

I never thought i'd be able to bend bindings in that dimension (?). i usually use ebony or koa at about 6mm height. i'll give it a try. thanks

[Barry Daniels]

I installed a small (approx. 3/8" diameter metal stud, 1/4" long) in my bending iron to accomplish this bend. This allows me to heat the side of the binding against the iron, while I have a small anchor to apply the bending force to accomplish the sideways bend. You need to get this spot pretty warm to bend it in this direction.

[Kary Karahadian]

Barry, can you achieve this bend with side purfling already glued onto the binding, or would the metal stud tend to crush it (the side purfling)?
thanks for the help.

[Bob Gramann]

I bend a binding piece and immediately glue it while it is still pliable (right after I get the whole piece bent). Sometimes, I take it back to the pipe while I'm gluing to make it fit better. The radius of the back was only a problem when I bent the day before I glued. I stopped doing it that way.

[Barry Daniels]

Kary, I always use side purfling glued to the binding and have not had a problem with crushing.

[Arnt Rian]

I usually start taping up binding at the butt end, as I think it is easier to do any miters etc first, and then glue and tape as I move along the rim. I don't do anything special at the waist, but I don't find it difficult to make the bindings conform nicely to the geometry of this part, even with wooden bindings, sometimes with side purflings. I use a 15' radius on the back too, my bindings are only about 1.5mm x 4.5-5mm (.06" x .18-.20"), I suspect thicker / taller bindings could cause some trouble. Also, the type of wood matters, ebony for example can be tricky. The good thing about using wooden binding and fish glue, as I do, is that it is relatively easy to adjust things after the fact, with some heat, moisture and judicious clamping.

[Pat Foster]

With stubborn woods, such as ebony, I've had some success by using spacers between the binding strips when putting them in the sandwich prior to bending, so that they approximate the "third dimension" curves they will encounter when they get glued to the body. If you can envision the curve of a pre-profiled side where it meets the back, that is the curve to emulate when spacing the bindings apart. In the sandwich, the butt end of the bindings should be further apart than the neck end, by double the amount of taper in the sides. This is still a work in progress, but it shows promise in reducing the "fight" that goes into gluing on the binding.

Pat

[Loren Schulte]

That's a great idea, Pat. What I've learned from using Ebony bindings is to not use them! BTW, it was great meeting you at Marylhurst.

[Pat Foster]

Loren,

Good meeting you too. See you there next year, maybe? Will you be at the GAL convention?

The idea on the binding came to me after talking to a well-respected builder I know, who cuts his sides to profile, bends them, then slices off the bindings from the sides. He says the bindings just about fall into place, but I'm not sure I'd always want the side and binding woods to match. It's a nice look, though. What I'd like to be able to do is replicate that shape of the bindings, in all axes, but done by themselves without having them cut them from bent and profiled sides. The result would be much like what Barry Daniels describes, but would extend to both bout areas, especially the upper.

Pat

[Steven Odut]

I used a 25' radius on the top and a 15' radius on the back of a classicial guitar with a cutaway. I found that I had to make some binding groove adjustments on both sides of the back, and a small adjustment to the binding groove on the cutaway side of the top in order to accomodate the radius geometry:

After cutting the binding groove with a router, I went back and, using a small scraper, made the groove deeper at the waist and at the apex of the cutaway. This makes the "hard-way" bend of the binding less severe when gluing it into place.

I used a spanish neck joint, so could not cut the binding groove right up to the neck with the router- the last inch or two was cut by hand. This allowed me to make the binding groove shallower as I approached the neck, also reducing the amount of "hard-way" bend.

Due to the hard-way bend, the binding also does not want to lie perfectly vertical at the apex of the bends, so using the scraper I sloped the binding channel a bit to accomodate the angle that the binding wants to lie at.

After all that, the binding was glued in, then scraped flush, and fit perfectly. This method is time consuming and fiddly, so I would want to find a better way if I had to make money doing this.

ps. bending the "hard-way" is term commonly used in metal fabrication to refer to bending a piece of steel around it's stronger axis. The "easy-way" bend is what you normally do when bending the bindings.

[Tom West]

Depth of binding an important consideration..........!!
Tom

[Trevor Gore]

My standard back has a 3m (10') dome, so the compound bend needs to be right to stand any chance of a decent fit. I bend the bindings on a hot pipe, putting in as much compound curve as I can and tightly tape the binding in position whilst it is still warm. If you tape the waist first it's easier to get the rest of the curves to lie properly. I do the glue-up the next day, by which time the forces required to pull everything into alignment are very much reduced.