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Bending Curly Maple Bindings

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Bending Curly Maple Bindings

Postby Craig Bumgarner » Wed Apr 24, 2013 7:21 am

I'm having trouble bending curly maple bindings, even to the relatively mild curve of the upper side. No idea how I'm going to be able to do the cutaway side. The maple seem pretty flexible but it breaks easily at a steep run out angle (45 degrees or more). I gather this is the nature of curly maple, the run out is a by product of the curl.

I've tried hot pipe bending and using a mold (two pieces of binding wrapped in tin foil, very light spritz of water, laid between two slats of spring steel, heat with heat blanket to 290 F (temp prob on the opposite of the wood from heat blanket, so pretty sure core of the wood is getting plenty hot). I'm bending the curves gently by glued hands and then clamping a matching block of wood to hold the curve, like a Fox bender. Of the last pair I did, one piece broke in 8 places, the other in 3.

I don't think gluing the breaks is much of an option as the binding will not likely lay fair at the breaks. Any suggestions?
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Re: Bending Curly Maple Bindings

Postby Jeff Chumley » Wed Apr 24, 2013 8:15 am

I bend maple on a pipe at about 375 degrees or so. Go slow. Don't try to get to the finished bend in one pass especially in the tight areas. Make sure the maple is quartersawn not slab. It is much easier to break if it is not quartered. Also, I highly recommend Supersoft. It is a product for flattening veneers but it works well for bending too. You spray it or brush it on and let it dry completely. It takes a day or so to dry. It plasticises the wood temporarily and the effect lasts for a few days. I've had the best success bending about 24 hours after application but they say it is effective for up to four days or so. It doesn't turn the wood into noodles but it does make it a bit easier to bend. I just bent .12" curly maple bindings for an OM and an L-00 last weekend with no breakage using Supersoft.

Also, I don't use water for bending curly maple. The curl in curly maple is caused by alternating areas of side and end grain and it soaks up water very unevenly. I think it often causes breakage instead of alleviating the problem.
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Re: Bending Curly Maple Bindings

Postby Craig Bumgarner » Wed Apr 24, 2013 8:34 am

Jeff, thanks for the reply. I'm using store bought curly maple binding with a bwb side purfling, 080". The grain is so neutral and small, I can tell if it is flat or quarter sawn. All I can tell is the breaks seem to follow the curl run out.

I'm thinking I will go back to the hot pipe. I think I had better control with it than the mold. Roger on hotter temp, Supersoft and no water. I usually bend purflings hot and dry, I tried water because nothing was working.
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Re: Bending Curly Maple Bindings

Postby John Sonksen » Wed Apr 24, 2013 9:29 am

Had the exact same problem until I got the temp hot enough. Once it was hot enough the wood turned into plastic. It's still not easy, scorching the wood at that temp is though so be careful. I managed to bend curly around about a 1 inch radius on my electric, without a backing strip. If you spritz do it very lightly. If you can see water exiting the side opposite the pipe you are too wet. It seemed like when I would do that I was expanding the xylem section, the space between growth rings that the tree used to transport water when it was growing, and immediately the growth areas on either side would separate. I did manage to stop that from happening by immediately stopping and letting it cool off but far more times it would just kink, like you said at about a 45 degree angle.
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Re: Bending Curly Maple Bindings

Postby Mark Swanson » Wed Apr 24, 2013 9:44 am

I think just a spritz of water just on the area of bending helps. You don't want to dry the wood so much it scorches, and only enough water added to make a little steam as you bend.
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Re: Bending Curly Maple Bindings

Postby Bob Gramann » Wed Apr 24, 2013 10:07 am

When I've bent maple bindings, I've found that water helps the bends get angular--depending on where it curls, it bends as straight line segments between angular points. I get the pipe very hot, bend dry, get the binding very thin, use a piece of flashing as backing on tight bends, and have spare pieces available because some pieces just don't want to bend. Home Depot in my region stocks maple boards. Some have some very nice curl. Every now and then, I find a nice one a bring it home. It makes nice binding for many many guitars--and it's cheap.
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Re: Bending Curly Maple Bindings

Postby Bryan Bear » Wed Apr 24, 2013 6:03 pm

Jeff said everything I was about to say. All I'll add to his post is that, while Super Soft II stays in the wood for several days, it is my understanding that when you bend it all "boils off." So if you need to re-bend (more than a touch up) you should re-apply a day before you do it. I haven't done it, but I have heard accounts someone bending a side and realizing he did it backwards and using Super Soft II to straighten and bend back the proper way.
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Re: Bending Curly Maple Bindings

Postby Trevor Gore » Tue Apr 30, 2013 1:44 am

Hot pipe and very little water and then only on the inside of the bend. SS 2 might work for you. Another trick is to add purfling to both the top and the bottom of the binding (use a high temp glue; LMII white works for me). The extra purfling helps hold things together and is scraped off once you've got the bindings glued on.
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Re: Bending Curly Maple Bindings

Postby Craig Bumgarner » Tue Apr 30, 2013 9:01 am

Trevor,

Purfling top and bottom sounds like a good idea. I have some SuperSoft II on order, (seems to be taking forever to get here), and will try that and your suggestion and we'll see how it goes. Roger on minimal water as you and others have suggested.

Thanks everyone!
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Re: Bending Curly Maple Bindings

Postby Bryan Bear » Tue Apr 30, 2013 12:22 pm

Interesting about the purfling Trevor. I once considered gluing some brown paper to the outside of a binding for bending on the pipe. I've never quite managed to bend binding with a backer without burning myself. I figured it would get scrapped/sanded away. Obviously purfling would provide better support, but paper is cheap and readily available in a pinch. I wonder if it would be up to the task.?.
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Re: Bending Curly Maple Bindings

Postby Trevor Gore » Wed May 01, 2013 2:56 am

Bryan Bear wrote:Obviously purfling would provide better support, but paper is cheap and readily available in a pinch. I wonder if it would be up to the task.?.

If you look through some of the older pictorial records of guitar making, you occasionally see pictures of sides covered in paper. Robert Bouchet is someone who comes to mind for using this technique. I've no idea what his intention was: avoiding stains, protection whilst bending or just so that marking-out lines could more easily be seen. If it was to provide protection against damage whilst bending, it would have to be fairly high tensile paper, I think.
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Re: Bending Curly Maple Bindings

Postby Craig Bumgarner » Thu May 02, 2013 11:36 am

Just a quick note to say I threw most everything suggested at the curly maple bindings and it worked. Used a 375 F degree pipe. SuperSoft 2 was a major help I think (did not wait 24 hours, roughly 18 hours, but wood felt dry. No moisture except just a little on the hot pipe side. Used a stainless spring steel strap. Only broke one piece and this was due more to me getting cocky and not using the strap on the relatively gentle bend in the lower bout. The strap seems to help most in the initial bends. Once the wood has decided that it will bend, it is actually easier to get the finished radii with gloved fingers working the wood, carefully supporting the upturned grain like the strap. Clamped bent pieces to side molds to settle into their new shape and fine tune the curves.

Thanks for all your help and encouragement, I was about to toss in the towel on this.
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Re: Bending Curly Maple Bindings

Postby Greg Marks » Thu Jun 15, 2017 11:56 am

This is my 1st violin build and the c/bouts are certainly prone to crack or split even by going slow. My ribs are soft curly maple at about 1-8mm. - 2.00mm. in thickness. I use a 1" diameter ceramic curling iron, range 400 F. When using super soft 2 what process did you follow when applying this product. I just spritz the bend with water. Would it also help to cover my ribs in foil and pre-heat with a heat gun before bending on my curling iron. Any advise would be much appreciated.thanks.
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Re: Bending Curly Maple Bindings

Postby Alan Carruth » Thu Jun 15, 2017 1:02 pm

Paper tends to be a lot stronger than you think it is. I've used the trick of gluing paper on the outside of a bend a number of times with sides that were being fractious. Any sort of glue seems to work. Use a thin soft aluminum back strap for added assurance, and keep it tight up against the wood. Other than that the general rule for curly wood are more heat and less water, and only wet the inside of the bend. I've found hard maple to be a bit easier to bend than soft, and skew cut to sometimes be easier than quartered.
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Re: Bending Curly Maple Bindings

Postby Stephen Neal Saqui » Thu Jun 15, 2017 6:01 pm

Anyone had success with the Fox bender?
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Re: Bending Curly Maple Bindings

Postby Todd Stock » Fri Jun 16, 2017 6:31 am

I have no issue at all on the Fox, to include very tight cutaways - SuperSoft II after CA'ing on the purfs and sanding to about .075". My usual bending practice - treat the day prior, add a 1" wide x .075" x binding length piece of scrap on either side of the bindings, use tape to keep the bundle snugged up to avoid purfling collapse in tight bends like Venetian cuts, and wet butcher paper versus directly wetting the wood in the bending package. Start bending at first sign of steam in the package, and dry for 40 minutes at 260-280 or so once bending is done. Curly koa, figured mahogany, and tassie blackwood get the same treatment and come out the same way. While rosewoods and ebonies are fine being pulled once cool to shop temp, curly maple and the mahoganies benefit from at least an overnight stay in the bender. The technique is essentially the same as what is shown in the 'Bending Figured Mahogany In the Fox Bender' videos on YouTube.

https://youtu.be/Q7vd9wGG4LM

All of my bender molds are at least 4 plies - with spring steel slats, that's enough support to avoid the sort of distortions that can show up in flat areas like the transitions into a dreadnought waist. Better still is a solid mold, but it chews up a lot of material at $50/sheet for hardwood core 18mm birch-faced plywood.
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Re: Bending Curly Maple Bindings

Postby Stephen Neal Saqui » Fri Jun 16, 2017 9:03 am

Thank you Todd!
I like using solid molds and spring steel slats. In San Diego I found some sheet titanium that I use for cutaway sides. It has almost NO memory. Unfortunately it isn't long enough and I haven't found any other source so far. I use it for the cutaway section.
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Re: Bending Curly Maple Bindings

Postby Greg Marks » Sat Jun 17, 2017 9:20 am

What type of paper did you use and what thickness did you shave your ribs to.
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Re: Bending Curly Maple Bindings

Postby Alan Carruth » Sat Jun 17, 2017 5:54 pm

I've used plain copy paper on 2mm (.08") sides, but kraft paper might be even better. I've used regular Titebond and CA: again T3 might be a better choice.
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Re: Bending Curly Maple Bindings

Postby Todd Stock » Sun Jun 18, 2017 6:37 am

Regular kraft paper works, with white kraft for very light woods like holly. I thin to 0.085", then sand or scrape the interior face, so usually 0.080" for maple, ash, mahogany, cherry, and other lower density woods. For tight cuts, that area will get thinned to 0.070"-0.075", then tapered back up to full thickness by the waist.
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