bending side purfling

[gerberguitars]

i've been wrestling with side purfling on my first five guitars. a few questions for the builders out there - 1) what kind of glue to you use to glue up your side purflings and to glue the purflings to the binding? 2) how do you go about bending the purfling/binding combo 3) do you bend the purfing already glued to the binding or separate?

i've been going over somogyi's book and he states that he bends the side purfling separate from the binding. but i can't seem to make sense of this. the inherent trouble with side purfling is that you're trying to bend it along it's tallest axis, without allowing to cave in or tip over, if that makes sense.

ryan gerber
www.facebook.com/gerberguitars

[charles Tauber]

1. Titebond.
2. hot copper pipe or Fox-style side bender.
3. Bend after side purfling is glued to bindings. Other than if one uses too much heat during bending the glue holding the side purflings together and to the binding can let go, I can see no reason to bend the purflings separately. I think it much easier to glue first, then bend. YMMV.

Lutes often have spacers between the ribs of the back. These are bend on edge (i.e. tall axis). A trick I learned years ago was to attach two pieces of copper pipe to the outside of my bending pipe. The two pieces are a little more than half circles of the same diameter as the base pipe, but sprung to fit snuggly over the base pipe. (You can cut an inch or two off the end of the bending pipe to make the two pieces.) The pipe wall thickness is maybe a 1/16" or so.

The two half rings are placed on the circumference of the pipe separated by the width of the purfling to be bent. The two half rings support/sandwich the purfling during the bending. It makes it fairly easy.

[SMan]

While taking Charles Foxs' acoustic guitar building class last year we used Titebond and "THE" Fox bender. Worked great. Just have to make sure they are in the correct orientation in the side bender so you have R & L sides. (They were glued up prior to bending.)

[gitnoob]

Originally Posted by SMan

While taking Charles Foxs' acoustic guitar building class last year we used Titebond....

That's interesting. I thought Fox pioneered the use of CA in this application. Rather than trying to glue your binding/purfling down a bit at a time, he fits all of the pieces at once, tapes them down, and then wicks CA in to secure the pieces.

I tried it that way once, and other than gluing my fingers to the binding, it worked very well.

[gerberguitars]

i have been using my side bender, with the binding strips taped together as tight as possible, wrapped in foil with plenty of water in the foil. a few observations that i've made: 1 - if they are taped too heavily, and the steam is not allowed to penetrate the wood, they crack in that location. 2 - CA glue seems to hold up under heat better than Titebond. 3 - after using these methods, and bending at about 325 degrees F, i'm still getting too many causalities. which is a real bummer when using an expensive wood like ebony, and after taking the time to glue them up.

what is your success rate?
do you bend with water or no water? and at what temp?

good to see the replies!

ryan gerber

www.facebook.com/gerberguitars

[Neil K Walk]

Originally Posted by charles Tauber

1. Titebond.
2. hot copper pipe or Fox-style side bender.
3. Bend after side purfling is glued to bindings. Other than if one uses too much heat during bending the glue holding the side purflings together and to the binding can let go, I can see no reason to bend the purflings separately. I think it much easier to glue first, then bend. YMMV.

Not to hijack this thread, but your comment about using "too much heat" seems to be ambiguous and I would think depends on the type of wood being bent. Then there's the temperature at which Titebond begins to soften too, correct? What temperature range do you usually work within?

FWIW my only experience with bending this far has been with mahogany, which I'm told is a good first wood to bend with and at 290-300 degrees F it went very easily (over 4 attempts!) Now I'm about to bend some Indian rosewood binding with BWB purfling though and I wondering if we need to make things a little hotter but like with the OP I'm not sure - though I'm fortunate to not have been "burned" in the past. I was also told that because Titebond will loosen up when heated that it would be better to just install the purfling separate. Is this not true - or at least partly true? I'm thinking that if the purfling is glued to the binding and comes apart under heat, then at least they both will get bent anyway so that you can just reglue everything together in the binding channel. Am I right in assuming this?

[charles Tauber]

Originally Posted by gerberguitars

i have been using my side bender, with the binding strips taped together as tight as possible, wrapped in foil with plenty of water in the foil. a few observations that i've made: 1 - if they are taped too heavily, and the steam is not allowed to penetrate the wood, they crack in that location. 2 - CA glue seems to hold up under heat better than Titebond. 3 - after using these methods, and bending at about 325 degrees F, i'm still getting too many causalities. which is a real bummer when using an expensive wood like ebony, and after taking the time to glue them up.

what is your success rate?
do you bend with water or no water? and at what temp?

Success rate, near 100%, rare to have a binding break while bending.

I Dampen the surface prior to putting in the bender; no foil; taped together in four or five places; hot enough that water put on the metal slats at the waist sizzles - I don't use a thermometer.

How thick are your bindings? Are you selecting wood with minimal runout for the bindings - that can make a big difference.

[charles Tauber]

Originally Posted by kwakatak

Not to hijack this thread, but your comment about using "too much heat" seems to be ambiguous and I would think depends on the type of wood being bent. Then there's the temperature at which Titebond begins to soften too, correct? What temperature range do you usually work within?

I don't use a thermometer. If I'm bending on a pipe, water sprayed on the pipe bounces like a hot griddle for pancakes. If softer woods begin to scorch, I turn it down a bit; if harder woods aren't bending right, I turn it up a bit. The bending wood tells me when the pipe is the right temperature. Sorry, it's qualitative rather than quantitative - that's how I learned and have had no reason to try to quantify it.

If on a Fox bender, when the water sizzles at the waist. Again, the bending of the wood tells me the pace at which to bend. I generally use one heat setting - full blast. It seems to work well regardless of wood type.

I was also told that because Titebond will loosen up when heated that it would be better to just install the purfling separate. Is this not true - or at least partly true? I'm thinking that if the purfling is glued to the binding and comes apart under heat, then at least they both will get bent anyway so that you can just reglue everything together in the binding channel. Am I right in assuming this?

I've not bent guitar side purflings separately then glued them to the binding or installed them separately at the same time as the binding. On some occasions, I have had some minor, localized separation of the purflings from the binding when the purflings are glued to the binding prior to bending. It is usually very easy to clamp and reglue them after bending, BEFORE gluing them to the guitar. The tightest bends are where this is most likely, such as the waist. I tape the bindings together at the waist to help eliminate this, which it generally does.

Others may have different experience.

[gerberguitars]

[QUOTE=

How thick are your bindings? Are you selecting wood with minimal runout for the bindings - that can make a big difference.[/QUOTE]


my bindings when bent are 7/64"

as for selecting pieces without runout, i'm not aware of how to do this. what does runout look like?

[charles Tauber]

Originally Posted by gerberguitars

as for selecting pieces without runout, i'm not aware of how to do this. what does runout look like?

From http://www.lutherie.net/frankford.runout.html.

I'm not suggesting that you split the wood from which to make bindings. But, choosing wood with little/no runout can be the difference between success and breakage.

[Howard Klepper]

Originally Posted by gerberguitars

my bindings when bent are 7/64"

as for selecting pieces without runout, i'm not aware of how to do this. what does runout look like?

Way too thick. Try .080".

[Kitchen Guitars]

I spent 2 days messing with a complex binding with spacers and rope Purfling. After it was bent I threw it out. Stuff slid, grain patterns did battle...... Neil saw the mess
One at a time for me.

I tape them down directly to a steel blanket. Spritz with water, put on another blanket and go to the bender.
As far as attaching. Best luck I have had has been Titebond for the working time. Also, the Stew Mac Binding tape has produced my tightest adhesion by far. Especially in the waist.

[Tom West]

For bending purfled bindings in a bender it's a good idea to tape them together in pairs,purfling to purfling.This helps prevent collapse of the purfling 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

[gerberguitars]

so far everyone who's responded uses the tried and true method of taping alternating strips together and sticking them in the bender.

seems like i need to be more aware of grain run out, and try to bring the thickness down a little bit. thing is i like the look of a thick binding strip.

i'm still curious how somogyi would go about bending the purfling strips separately? one huge advantage he has i doing this, is that he can cut his binding strips out of one large pre bent piece, just like a side would be, while clamped in a domed mold to match the radius of his top and back. he clamps the side in the mold, then uses an upright dremel or laminate trimmer with a slotting cutter blade on it, and moves around the mold. the result is that the binding strip with have the appropriate radius as it moves from end block to neck block. since i use a 25' top and 15' radius back, this would help tremendously in getting a good fit and not having to fight the binding strip while it tries to bend in 4 directions as i tape it in place.

any thoughts on this? i'm guessing he just tapes the alternating purfling strips together and bend's them the same way you would the binding. anyone had success with this method?

ryan gerber
www.facebook.com/gerberguitars

[charles Tauber]

Originally Posted by gerberguitars

i'm still curious how somogyi would go about bending the purfling strips separately? .. one huge advantage he has i doing this, is that he can cut his binding strips out of one large pre bent piece, just like a side would be, while clamped in a domed mold to match the radius of his top and back. he clamps the side in the mold, then uses an upright dremel or laminate trimmer with a slotting cutter blade on it, and moves around the mold...

Do you have some reference for this? His book shows standard methods being used, recommending Titebond and .090 thick bindings. He repeatedly says to choose wood with minimal runout. Not sure from where you are getting your information. I'm no expert on Somogyi's proprietary methods, but what is shown in his book is standard fare, nothing of what you are describing.