How would you glue this?

[Quickstep192]

I'm planning to put binding and purfling on a banjo resonator. I might have posted this on the Banjo Building forum I'm a member of, but banjo builders don't put purfling on resonators - perhaps i'm about to find out why

Unlike a guitar, the purfling isn't supported on the inside as you can see in the attached drawing.



I figure I can either glue the binding first, then glue in the purfling, or try to glue them both at once.

If I glue the binding first, I'll likely need to clean up some squeeze out which may be tricky. Conversely, gluing both at the same time, might be tricky since the inside isn't supported at all.

Either way, I'm planning to use LMII's FCA glue which is supposed to be good for plastic to wood, which is the situation I face.

Any ideas ?

[Alan Carruth]

If the purfling is in the form of stripes I'd glue the binding on first. Alternatively, you could clamp on some sort of no-stick material, like UHMW polyethylene, in place of the binding, and glue the purfling up against it. This will avoid problems with strips over hanging; they'd need to be trimmed off and you'd end up with uneven lines. If the purfling is diagonals than I'd just glue that up, file off the inner side of the binding rabbet, and put on the binding.

I do wonder how durable this will be as shown. The glue line between the wood and plastic is often pretty weak. Normal binding and purfling is backed up against side impacts by the wood of the rabbet, but this is exposed. It's probably too late to re-rout it to leave a little ledge of wood inside the purfling on the top.

[charles Tauber]

Just based on your drawing, I'd be inclined to install the purfling as a cap and then route the rabbet for the binding into the purfling, leaving behind the desired amount of purling, then install the binding.

But, it isn't clear from the drawing or your description what the make-up is of the purfling. If it is guitar-like purling - individual thin strips installed to make a wider amount, probably that isn't the way to do it.

[Quickstep192]

The purfling is wood marquetry, kind of like herringbone. I have bent it into a circle that's reasonably close to the final size.

I like the idea of creating a non-stick binding so I can glue the purfling on first. That way, I could glue wood-to-wood for a stronger bond, even though the surface is only .1 wide. Now I just have to figure out how to hold the uhmw in place.

[dekutree64]

[Quickstep192]

I wish I had thought of dekutree's idea before the binding channel was cut! But alas, that ship has sailed. I suppose I could put a piece of binding in there and rout it back out later, but the border on the purfling is pretty narrow and I'm concerned that I might mess it up during that operation.

[Quickstep192]

Thanks to your ideas, I've made progress. Thank you all very much.

I made a form to allow me to glue just the purfling in place. I now have the purfling glued on, so I'm at this stage:





and now need to glue on the binding.

I used Luthiers' Mercantile Yellow Instrument Glue to glue on the purfling (red part). It seems to have worked well. On the edge where the binding will go, there are some spots where the glue got between the form and the wood. It's very thin, flat and smooth, so I'm not eager to go scraping on it unless I have to. So, the question is, will the binding glue stick to the yellow glue residue? The binding glue is Luthiers' Mercantile FCA which is a solvent based glue.

http://www.lmii.com/products/finishi...ding-adhesives

As always, your wisdom is appreciated.

[mirwa]

Solvent based glues are the way to go for plastic bindings and or purflings.

Wood glue for fabric or wood bindings.

As far as solvent based glue on top of wood glue, IMO not really, I have seen many guitars come in that have had at some stage both glues applied, best to give it a light scraping to clean the surface.

Steve