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View Full Version : Binder and Purfling bending for classical guitars and ukes



Bill Dillon
07-14-2012, 8:31 PM
Binder and Purfling bending for classical guitars and ukes (http://www.mimf.com/phpbb/viewtopic.php?f=3&t=1073#p10034) http://www.mimf.com/phpbb/styles/prosilver/imageset/icon_post_target.gif (http://www.mimf.com/phpbb/viewtopic.php?p=10034#p10034)by Bill Dillon (http://www.mimf.com/phpbb/memberlist.php?mode=viewprofile&u=152) » Sat Jul 14, 2012 11:35 am
I need some help, hints, advice. I'm new at lutherie and after building one perfectly satisfactory classical guitar at a lutherie school in Vermont last year, am now working on two ukulele's and one classical guitar. I've reached the point where I have cut/routed the channels for the purflings and bindings and am now attempting to bend them to the correct shape. I'm using an LMI teardrop electric bending iron (which worked fine on bending the sides) and having a bad time with the bindings breaking as I try to bend them. The bindings are rosewood 0.080. I've tried bending them dry and wetting them. Once or twice I've been able to "feel" them let go a bit and bend. but then the break before I get them bent enough to fit the uke waist. Any suggestions any of you might have will be most appreciated. Thanks, Bill

John Coloccia
07-15-2012, 1:23 PM
Back up the bindings with something as you bend them. I use a piece from a small pocket tape measure. I forget where I got that trick from, but it works. It will keep the wood from cracking at the back. It also helps retain a little more moisture, which in turn helps retain heat, and it's the heat that you need for bending.

george wilson
07-16-2012, 9:28 AM
I bend the bindings and purflings that go into the waist a little too much. This helps,I believe,these strips to keep from wanting to pull away from the waist in years to come,as you sometimes see in vintage guitars,especially with plastic bindings. It tends to keep the bindings putting pressure on the waist rather than wanting to straighten out. Celluloid bindings can be bent with a heat gun,but be careful,or they'll get fried if you get them too close to the exhaust of the gun.

Bill Dillon
07-19-2012, 11:08 AM
I posted this request on three forums and received several excellent and useful suggestions. THANK YOU, EACH OF YOU, FOR YOUR HELP!

Chris Fournier
07-29-2012, 11:49 AM
I don't have an image of my teardrop shaped electirc bender right now but I have added a fixture to the top of it which works very nicely. If you unscrew the aluminum housing from the bender you will see in the casting at the top on the inside that there is a portion of the casting that has lots of material - enough material to drill and tap threads. I turned down some aluminum about 2.5" long into three different diameters, like spools stacked on top of each other the smalled rad is about 0.1875" and the largest is maybe 0.5". I turned threads on the bottom and fastened this to the top of the bender. It heats up quickly and now you can bend small delicate parts with a bit more ease. I use this fixture to bend maple bindings that fit inside f-holes so deilcate work can be pretty easily achieved. I made this modification to a mandolin builders bender and he says that it has really improved his bending outcomes. I've added a quick sketch.

Don Parker
07-29-2012, 9:49 PM
I use a bending form with a silicone heating blanket for sides as well as binding and purfling. Sandwiching the wood between two steel slats and the heating blanket really does a lot to minimize breaking. It is not as easy to "overbend" as George suggests, but with planning regarding the shape of the form, you can do that, too.

If you go with the form, it is best to bend all of the bindings and purflings at the same time with everything taped together. It helps avoid racking.

george wilson
08-02-2012, 11:08 AM
As John suggests,using a tape measure behind the bending helps. German irons used to,at least,come with a stainless steel sheet with handles at each end, You could easily make one out of thin gauge stainless steel,with wooden handles screwed to the ends. The large ones for the sides were about 18" long,and 4" tall.