Puckering Purfling

sequoia

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Anybody have any suggestions on how to bend laminated wood purfling side on so it doesn't pucker? Wood gonna do what wood gonna do and it doesn't want to do what I want it to do. Any ideas would be appreciated.
 
As far as I know, you have to heat bend it on a bending iron, but, I have to admit, I haven't had any luck with that method yet!

Bob
 
I have a little tutorial on bending binding and simple purling on my website page http://www.pegasusguitars.com/bending-binding-and-purfling.html . The quality, or material make up of the purfling has a lot to do with whether it will wrinkle up or not. Usually wood purflings bend O.K., with little wrinkling. The black and white combo purlings from Korea and China that you find on eBay though, are often just what seems to be compressed paper. Those will wrinkle badly in the waist or cutaways, but not to worry. You can iron them flat with a regular iron and they usually come out very useable. More complex purflings, like herringbone, often have to be slightly taken apart to be bent. Lots of fun! Lots to learn.
 
Lots of fun! Lots to learn.

I should have been a little clearer in my post. I've been having problems with the purflings delaminating from the binding when I bend the binding. The frustrating thing (I'm frustrated) is that I have not had this problem in the past at all. Now all of a sudden it is a problem. So my idea was, screw it, I will bend the binding without attached purfling and then drop in the side purfling when I do the glue up. Well it ain't easy to bend purfling when it isn't attached to binding. I spent the afternoon ruining a lot of purfling. So... that approach is not going to work. Back to laminating it to the binding. I'll work it out. I've done it before, but sometimes building ukes can be frustrating. What I'm doing is forcing wood and wood wins in the end. Score it: Uke builder: 0 and Wood 1. Wood wins.
 
I read that Titebond II is the glue to use if you are going to heat and bend wood.
 
I scrape away the inside edge as far as i dare .

The less material (this applied to anything your bending), the easier it gives and doesn
t show symptoms of resistance like wrinkling.
 
I glue them to my bindings prior to bending both them and the binding together.

Same here. Its still hard to get it to bend into a ukulele waist with out ungluing from the binding. Good luck
 
I bend and glue in the side purfling before the binding. Bending it requires a 2 clamps for your bender set so the purling fits between them. This way 3 sides are supported and it can't buckle. bwb is much easier to bend than wbw if the "w" is maple; if its all fiber, then it's easy either way. Be sure to fit the clamps with only a few thousands of clearance and turn the heat down more than normal. Photo 1 is a bent piece of bwb, and photo 2 shows a gauge I use to set the space between the clamps.

bending1.jpg bending2.jpg
 
I bend and glue in the side purfling before the binding. Bending it requires a 2 clamps for your bender set so the purling fits between them. This way 3 sides are supported and it can't buckle. bwb is much easier to bend than wbw if the "w" is maple; if its all fiber, then it's easy either way. Be sure to fit the clamps with only a few thousands of clearance and turn the heat down more than normal. Photo 1 is a bent piece of bwb, and photo 2 shows a gauge I use to set the space between the clamps.

This is friggin' brilliant. Hats off to you!
 
I tried something a bit different this last time. I tape the four pieces of purfling together side by side and bend them as one by hand using the two metal bands that came with the bending iron to keep the purfling straight. Moderate heat, as close to the body shape as I can, taping them inside the mold until they cool. I had been gluing them in the channel separately. But what I did different this time was glue them to the bent binding wrapping the entire length of the binding with blue page, making sure that the inside face of the purfling was flush with the inside face of the binding. I wanted to have a slight lip of the purfling protruding on the outside that would be easy to scape down flush and give a clean line. I then knocked the inside corner off with a small file before gluing the whole thing into the channel. I did have a slight problem with the purfling delaminating, but it was easy enough to reglue. As for wrinkling of the purfling, I had had little problem with the fine multi line purfling that LMI sells.
 
I had had little problem with the fine multi line purfling that LMI sells.

LMI's purfling is all fiber and you can almost tie it in a knot. Stewmac's purfling is fiber and wood, and the wood portion isn't as forgiving as fiber, but looks more natural under a finish. Beau mentioned scraping it thinner at the bend which does work. I use a spindle sander to thin only the portion at the bend, and turn the scalloped side in so there is excess material to scrape on the outside.
 
After spending an afternoon in the Purfling Bending Laboratory, I think that it is possible to bend purfling end-on, but not by me. At least not very well, so I'm going back to laminating it to the binding and bending it that way. It has me thinking however; is side purfling even really necessary? Of all the things I do, this is pure bling. It contributes nothing to structural integrity or the sound of the instrument. Purfling on the top side sure, but why bother with side purfling? Well, I do it because it looks cool, it is fun, but is it necessary - I don't think so. Will I continue to do it? Probably, but I think an uke without it would look perfectly fine. Below a picture of some side purfling I did with the pre-laminated stuff from SMD.

DSCN6039.jpg
 
OK. After bending there was severe delamination. With some judicious coaxing, I was able to pin things down with clothes pins. Happily after letting dry over night night the glue "re-activated" and held the purfling. No harm. No foul. No re-gluing needed.

DSCN6043.jpg

Puckered binding going in:

DSCN6040.jpg

Puckering sands out:

DSCN6044.jpg

Final box coming to shape. Not perfect, but I will take it.

DSCN6045.jpg

But really, I think this side purfling is more trouble than is worth it.
 
That looks pretty.

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Which brings me to my question. I have noticed most people post links to their picture rather than have them come up when the page loads. I am guessing it is not by accident. You people actually like it better that way? Pictures are half the reason I come to these forums. Even if I see a picture multiple times I still appreciate the instrument or process the poster is showing. Also If I want to go back to look at a particular picture I have a tough time remembering if it was img 005832.jpg or img 005843.jpg. I know when in Rome do like the Romans, just curious on the reason.
 
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