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| Bending Koa for Archtop F-holes http://www-.luthiersforum.com/forum/viewtopic.php?f=10102&t=3794 |
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| Author: | npalen [ Mon Nov 14, 2005 8:09 am ] |
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Sure could use some advice. I'm needing to bind Benedetto style F-holes which requires very tight bends of roughly 5/8" inside diameter for the end curls. I'm thinking that the binding will need to be no more than, say, .050" thickness to even have a chance. Wondering about jury rigging a heated mandrel around which to bend, the mandrel being shaped to match the F-hole curl. Perhaps have this on end when bending with a central hole down the middle and exit holes spaced around the OD of the mandrel purpose being to pour a little water into the hole to produce steam. I've never bent Koa so a little apprehensive to say the least. Any words of advice such as a heat source would be greatly appreciated. Nelson |
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| Author: | rlabbe [ Mon Nov 14, 2005 9:14 am ] |
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Nelson, I don't know if this will help, but I recently bent curly koa to an inside diameter of 1". I just used an electric soldering iron (the pencil type). I wrapped the barrel with aluminum foil to keep the iron clean, and bent the wood on the wider barell, rather than the thin, hotter tip. I'll be honest and say I snapped my first piece, but the second went fine. I didn't bother measuring the thickness, but I went a bit thinner than normal binding, but not by too much. |
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| Author: | Dave Rector [ Mon Nov 14, 2005 10:45 am ] |
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Nelson, there was a thread on MIMF a while back where Mario bent a piece of binding to something like a 1/4" radius. I believe he said he just heated up a bolt with the right radius using a propane torch and bent it right over the bolt. Maybe Mario will chime in and offer more info. |
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| Author: | Brad Goodman [ Mon Nov 14, 2005 12:06 pm ] |
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Nelson, When I bind my head I couldn't bend the tight radius with the .090 curly maple I was using so I actually cut it out of solid wood-sounds crazy,but you can't tell inthe finished product-it looks like bent binding. For the f holes I used thinner material and it bent fine. 
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| Author: | D.L.Huskey [ Mon Nov 14, 2005 1:17 pm ] |
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Nelson, I'm binding the inside of the F-holes on a guitar I am working on. The material I am using isn't Koa though, It is Walnut and Black Gum about 1/32"(.031)thick. For making the bends,I am using a 5/8 Socket on an extension clamped onto the table and heating with a torch. Crude but it is working. |
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| Author: | Shawn [ Mon Nov 14, 2005 3:35 pm ] |
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Unless you are looking for the look of mitered points on your f-holes, since you have a CNC setup why not mill it out of solid material or out of a sandwiched veneers. If you are cutting the f-holes on the CNC you could easily setup to cutout to the outside shape of the f-holes, then strengthen with tape or glue to a substrate and then cutout a inner cut that would allow you to pop in this lip to the inside edge of the f-holes. While unconventional it would be a feature that would have people wondering how you were able to cut it. Alternately if you are looking for the multiline look as Brad shows in the photo above, you could laminate each of the lines one at a time onto the edge of the f-holes and then flush sand once all lines are in. |
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| Author: | npalen [ Mon Nov 14, 2005 4:03 pm ] |
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CNC F-hole binding out of solid? You guys have to be kidding me--that would be cheating. Okay, well maybe this one time. 
Seriously, I'm curious how that would look as most of the cut would be at angles to the grain. Might be pretty cool. I believe the Collings factory tour on Frets.com shows them cutting mandolin headstock and neck bindings and purflings out of "the solid" now that I think about it. F-hole bindings for an archtop would have to be cut from a rather thick piece of material due to the elevation change around the perimeter. I do appreciate the tips on bending,guys, I'm probably trying to make it more difficult than it really is. Brad, wow, very nice work! |
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| Author: | npalen [ Tue Nov 15, 2005 2:24 am ] |
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BENDING IRON Thinking about adding a 5/8" dia. "nubbin" to my bending iron similar to what Stew/Mac shows here. Can I drill and tap a mounting hole in the end of the bending iron? Anyone have the "mandolin" attachment for the bending iron? Does it use a screw to attach it? Thanks Nelson |
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| Author: | Anthony Z [ Tue Nov 15, 2005 3:03 am ] |
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Nelson, a 5/8" OD "nubbin" might be a bit too large if the inside radius of your f hole is 5/8". I use a 3/8” O.D. pipe attached to a “T” and a flange that I clamp to my workbench. I heat the pipe with a $5 Radio Shack soldering iron. I also use a female caul the shape of my “f” hole when bending. I’ve only bound “f” holes with maple so I am not sure whether you would have to do anything different for Koa. I think your question nets down to is whether Koa is more difficult to bend than maple? Brad, that's very nice looking work!! |
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| Author: | npalen [ Tue Nov 15, 2005 3:07 am ] |
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Anthony--Probably time that I quit cutting bait and go fishing eh? 
Nelson |
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| Author: | Pwoolson [ Tue Nov 15, 2005 4:32 am ] |
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Nelson, you might contact Watkins. He just developed a headstock binding method out of solid that knocked my socks off. |
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| Author: | Brad Goodman [ Tue Nov 15, 2005 5:04 am ] |
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Nelson, I have one of the older electric bending irons and bought the smaller diameter pipe from stew-mac and drilled and tapped the iron to accept it. I like having the smaller diameter to bend with. |
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| Author: | John Watkins [ Tue Nov 15, 2005 5:47 am ] |
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Thanks, Paul. Nelson, maybe this will give you an idea of what it might look like out of solid material. 
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| Author: | John How [ Tue Nov 15, 2005 5:53 am ] |
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You guys and yer dang CNC machines 
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| Author: | npalen [ Tue Nov 15, 2005 6:05 am ] |
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Way cool, John. I assume the top purfling was done by the conventional method. Or was it CNC'd also? Brad--Any idea how deep one can safely drill without getting into the heating element? Nelson |
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| Author: | John Watkins [ Tue Nov 15, 2005 6:11 am ] |
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Thanks, Nelson. The maple was cut separately with a .020" offset and then inlayed into the cherry. The black line is the adhesive; black epoxy. |
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| Author: | npalen [ Tue Nov 15, 2005 6:22 am ] |
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You're getting tricky in your old age, John.
Here's some cool CNC binding tricks also: BINDING |
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| Author: | Jim Watts [ Tue Nov 15, 2005 6:50 am ] |
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Nelson, Koa bend pretty readily at .06. I've done head stocks at .06 no problem, but to honest I haven't done f holes. You should give at go though, you might be surprised. |
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| Author: | Anthony Z [ Tue Nov 15, 2005 10:38 am ] |
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Hey Nelson -- just like the Nike theme "JUST DO IT"
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| Author: | Brad Goodman [ Wed Nov 16, 2005 1:05 am ] |
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Nelson, I can't remember exactly how deep I drilled into the iron(it was along time ago) but it was something on the order of 1/4". |
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| Author: | Dale M [ Wed Nov 16, 2005 1:25 am ] |
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I read all of this with great interest as I am now carving the top for a Benedetto style arch top. I may bind with (gulp) plastic since I`m building this one of mahogany. I really like plastic on mahogany. Some how it just looks correct. I`ve carved the back(actually a three piece with a wedge of flamed maple in the center) and it rings like a bell when tapped! I`m tempted to build the next one, top and all of mahogany. Comments? |
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| Author: | csullivan [ Wed Nov 16, 2005 6:05 am ] |
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Dale, I think plastic often gets a bad rap. If you look at many of the D'Angelico or D'Aquisto guitars, many (if not most), were bound with plastic (celluloid probably back then). I'm with you -- I think it looks quite appropriate. As far as mahogany is concerned, I've never built an archtop with a mahogany top, but there have been many beautiful sounding guitars built with mahogany tops, both flat and arched. Sounds like you'll have a winner on your hands. Looking forward to seeing the pics along the way. Craig |
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| Author: | Anthony Z [ Wed Nov 16, 2005 1:20 pm ] |
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Dale, I am with Craig as well -- nothing wrong with plastic binding on an archtop and it should look great with mahogany. Wood binding tends to be the exception on archtops. Binding the f holes in wood I found takes 3 times as long to do as plastic (others like Brad Goodman are no doubt quicker). Not many pro archtop builders offer wood binding and if they do there is a pretty hefty uplift on the cost or if they offer wood binding they don't bind the "f" holes. Just out of curiousity, have you built an Archtop with a spruce top? |
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| Author: | npalen [ Wed Nov 16, 2005 4:59 pm ] |
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Don't let 'em kid you, those guys with CNC don't even own any hand tools.
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| Author: | Dale M [ Wed Nov 16, 2005 10:54 pm ] |
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Anthony, this is my 1st arch top. It`s something I`ve always wanted to try so here I go! I was so suprised at the lovely sound when I tapped the mahogany back that It made me think it would serve as a great top. I hand carved the back but I`ve borrowed a friends home made duplicator to shape the top making every effort to be true to Mr.B`s specs. I`ve just about finished the pattern and will set up the duplicator soon. I`m taking pics but have not figured out how to get them up to the web site. I`m a babe in the woods where computers are concerned! |
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