bending side purfling

[SMan]

Originally Posted by Tom West

For bending purfled bindings in a bender it's a good idea to tape them together in pairs,binding to binding.This helps prevent collapse of the binding and ensures a set for top or back. I use titebond for gluing purfling to binding and have no doubt the glue softens during bending but sets again during cooling. No problem because the set is taped tightly together. I just use masking tape,a bit of work to clean up but works nicely.
Tom

As in the picture I posted above that is exactly how I was taught by Charles. The blue painters tape worked perfectly to keep the purfling and ebony binding together during the bending process.

[Ned Milburn]

I have had good luck so far using Titebond 3 (waterproof, so you can wet the binding/purfling vertical combo) then bending on an iron. Thinner purfling strips seen on the top of the guitar don't even need to be bent as they have enough flexibility as-is.

As another poster mentions, I also don't measure the temperature of the bending iron. If the water jumps on the iron and the wood bends well, it is the right temperature. I know nothing, however, about bending jigs and machines, and likely never will. Spanish method for me (except with the modern convenience of electricity; I would guess they used iron rod heated in a fire years ago.)

[gerberguitars]

see page 110 in "the making of the responsive guitar". here he is actually talking about cutting the binding on a tapered body guitar, where the bend on all four axis is much more severe. here is where he cuts the binding first with the method i referred to above, and then glues pre bent b/w/b purfling to it with clothespins.

so i guess i was mistaken. you are right in saying that for normal guitars, he glues up the binding and purfling stack first, cut's to .090" and bends. he says to avoid runout to start with a slab cut piece of wood, stacked with the purfling veneers on the bottom. i'll start doing it this way instead of assembling the binding pieces one at a time.

however, i come back to the thought about this method of cutting out the binding while clamped into the mold, in order to have the appropriate radius cut into the binding, then gluing the purfling. i like this idea, and when i get time to radius the top of a mold, i think i'll try it.

ryan gerber
www.facebook.com/gerberguitars

[charles Tauber]

Originally Posted by gerberguitars

see page 110 in "the making of the responsive guitar". here he is actually talking about cutting the binding on a tapered body guitar, where the bend on all four axis is much more severe. here is where he cuts the binding first with the method i referred to above, and then glues pre bent b/w/b purfling to it with clothespins.

Ah, thanks. I read the material on "regular" binding. When he got to installing it, I figured he had finished what he had to say about making bindings.

I've made some pretty severe cutaways and never had a problem fitting "regular" straight bindings to it. Unless the arch/dome is severe - way more than typically found on most guitars - I've not found it to be an issue bending the bindings on edge to fit the rabbet between the sides and domes top or back. There are many ways to achieve a desired result, none is right or wrong if it produces the desired result. Some, however, are quicker and easier than others.

I've not made a wedge-shaped guitar so I won't comment on the need to do this or not.

He does mention on page 110 that he cuts a slot in his bending pipe with a hacksaw and that the purfling will just fit in the slot for bending on edge. I like the solution I was taught better, since it creates an adjustable-width "slot", allowing one to bend strips/purflings of different widths.

[Tom West]

I have edited my last post in this thread. Read it this morning and I must have been asleep when I posted. Makes a bit more sense now. Sorry about that.
Tom

[Stephen47]

I assume the purfling you are discussing here is the purfling line at the bottom of the binding not the purfling that goes in a shallower channel on the face or back of the guitar. Because I don't see how it would be possible to glue this up as one piece.

[Tom West]

Stephen: Yes, side purfling not for top or back.
Tom

[gerberguitars]

An update to my side purfling struggles. I now use a method where I bending a large piece of wood, whatever the binding wood may be. I bend this the same way I bend a side. I then put bent piece in my mold with a dome caul that surrounds the perimeter of the mold and matches the radius of the top or back. This dome was cut on the Cnc, in the same way a radius dish would be made, accept it's convex instead of concave. I then use a fein saw with a round flush cut blade and cut the protruding piece of wood at about 3/8" tall, making this my binding. The nice thing about doing it this way, is that on a 15' radius back, and even the 25' radius top, I don't have to fight the bend on all 4 axis. It fits perfect around the perimeter of the binding channel, as well as over the dome axis of the binding channel. For side purfling, I bend the purfling piece by piece with a clothes iron, bending it flat, to match the contour of the guitar. This is done pretty quickly and easily. Then I super glue the purfling strips to the bottom of the binding, and it's ready. It's a lot more work, but I believe that end up with a much better result.

[charles Tauber]

Originally Posted by gerberguitars

It's a lot more work, but I believe that end up with a much better result.

Reminds me of the kind of thing Overholtzer used to do - "back in the day".

Way over-kill, I think, but as long as it works for you, that's all that matters.

[gerberguitars]

Originally Posted by charles Tauber

Reminds me of the kind of thing Overholtzer used to do - "back in the day".

Way over-kill, I think, but as long as it works for you, that's all that matters.

What radius do you use for your backs? And do you use rope or just tape?

Thanks for your contribution to this post (:

[charles Tauber]

Originally Posted by gerberguitars

What radius do you use for your backs?

For backs, side to side, I use a 3/16" rise over a 16" run. End to end I use a 3/16" rise over the length of the back. For tops, 1/8" rise over 16" run. I've calculated what those equate to as a radius, but don't remember off the top of my head, but they are fairly typical values. I haven't used spherical dished forms.

And do you use rope or just tape?

I've used rope, tape and elastic bands - not all at once. I've found all are about the same, more or less and all will work.

Thanks for your contribution to this post (:

Not sure if your being sarcastic or not...

[gerberguitars]

Originally Posted by charles Tauber

For backs, side to side, I use a 3/16" rise over a 16" run. End to end I use a 3/16" rise over the length of the back. For tops, 1/8" rise over 16" run. I've calculated what those equate to as a radius, but don't remember off the top of my head, but they are fairly typical values. I haven't used spherical dished forms.



I've used rope, tape and elastic bands - not all at once. I've found all are about the same, more or less and all will work.



Not sure if your being sarcastic or not...

So do they have a convex shape side to side only? Or is it domed from end to end as well? Sorry for so many questions, just trying to understand exactly what you do. Do you dome the rim assembly?

I'm not being sarcastic (: I really do appreciate it.

[charles Tauber]

Originally Posted by gerberguitars

So do they have a convex shape side to side only? Or is it domed from end to end as well?

As I stated, for the back, a 3/16" or 1/4" rise end to end and a 3/16" rise for a 16" run across the width.

Do you dome the rim assembly?

Yes, but I don't use spherical dishes - the curvature is not spherical. The use of spherical dishes is a relatively new innovation in guitar making. Before that, as far as I know, no one used a true spherical shape in the curvature of top and back plates.

I have nothing against the use of spherical dishes, it just isn't the way I was taught and I've never made the transition.

On the top, the upper bout is flat, lower bout domed, but not spherical.