Bending wildly curly wood

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Bob Gleason
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Bending wildly curly wood

Post by Bob Gleason »

Just curious if anyone here has experience with wrapping super curly wood in tin foil before bending. Living in Hawaii I'm stuck having to use curly koa because it is just the wood of choice for players. Nice wood, but believe it or not it gets boring after 35 years! I've probably bent more than 1,000 sets of uke/guitar wood over the years. I do occasionally run into unbendable wood. I've read about people wrapping wood with tin foil and am curious about how well it works. Any experience? Good or bad? Your process? Thanks, Bob
tippie53
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Re: Bending wildly curly wood

Post by tippie53 »

I used it but prefer untreated paper and windex

Just bent Koa this week I find water staining a problem with the koa and foil
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Bob Gleason
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Re: Bending wildly curly wood

Post by Bob Gleason »

I have continued to pursue info about using tin foil for bending. Several builders gave me input and I gave it a try yesterday. The bend was on very curly koa ukulele wood. I wrote this little piece up for our Guild and thought i'd post it here too. Those of you on the Mainland who don't have to work with curly koa are lucky. Most other woods don't have any bending issues, and I would not bother with the tin foil. As with a lot of first time things I try, I don’t know if was beginners luck or what. The results were significantly different from bending I’ve done before. The wood was very curly, and though I still experienced a teeny tinny bit of tearout about 1/4” long on 1 side, the process went really well. I was surprised at how different it was from my usual experiences. If there was a down side, it was that there was a bit of staining on the inside of the wood, downside in the press. Not too bad though, and sandable. Could easily have been due to the volcanic junk that is in the catchment water these days. I’ll try distilled water next time. Good chance it won’t happen if I can fine tune the process.
My process:
1. Fine sand and profile the side.
2. Wrap it in a couple of wraps of end role paper from the newspaper. Any clean, wax free paper will work.
3. Spray both sides of the outside of the paper.
4. Wrap it with 1 1/2 wraps of tin foil with the ends bent over to seal the package.
5. Put it in the bender. Timer set to 10 minutes and the temp set to 320 degrees.
6. Here’s where the process really changed and surprised me. Normally, without the foil I would do the 10 minute bending process, from the time I first put the wood on the cold bender and turn on the blanket. After 10 minutes the wood was always still slightly wet and not fully set to the shape, so after the mold cooled I would always turn the bender on again, take it to 300 degree and turn it off. That set the shape and helped dry the wood. Bending the foil wrapped wood today, I made the normal bending sandwich of 1 sheet of aluminum flashing on the bottom, the wet paper and foil wrapped wood, the blanket, and a final sheet of flashing. I did the same amount of time on the bender and same temp of 320 degrees. I assumed the foil would not let the wood dry out and I would have to run the bender again. Not so! Using the 10 minute timer setting the wood was completely dry and nicely set to shape.When the temp returned to 100 degrees I was able to remove the side and transfer it to the holding mold. That took at least 20-30 minutes off my old bending process. Nice! That was surprising. And, I think the curves of the bent side were smoother than I have gotten before.
Now admittedly it could have been beginner’s luck, or the vog, or what I had for breakfast, but I’m encouraged to try more experiments with the foil. Enjoy your building!-Bob
tippie53
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Re: Bending wildly curly wood

Post by tippie53 »

interesting
what thickness? post pics
it is nice to see ways to do things
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Bob Gleason
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Re: Bending wildly curly wood

Post by Bob Gleason »

John- Before I do an all out endorsement of this process, I need to try it a few more times and work on some variables, like using distilled H20, playing with the temp., and using the stainless slats I just ordered from you instead of the aluminum flashing. The simple method of just wrapping the wood in wet paper, like you and I have been using for quite awhile, has demonstrated that it works.I just like trying new stuff. Keeps things interesting. Always looking for the holy grail of any part of the building process! I will do a follow-up with more info and photos. My uke wood is about 1.8mm/.070 thick-.075 thick when I bend.
tippie53
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Re: Bending wildly curly wood

Post by tippie53 »

try the windex I found that to better than water
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Bob Gleason
Posts: 412
Joined: Fri Jul 03, 2015 2:45 pm
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Re: Bending wildly curly wood

Post by Bob Gleason »

I did try Windex before I tried the tin foil and it badly stained the koa. Had to toss out the sides. Have not tried it with the tin foil. I need to take a different approach to this experimenting. Normally I have no patience for , as they say "try on scrap". I'll often just go for it with whatever project I'm working on. I'm going to try a more sensible route and make up a bunch of sleazy koa sides to experiment with. Won't be much extra work as I can use them right out of the wide belt sander without having to do any finish sanding.
tippie53
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Re: Bending wildly curly wood

Post by tippie53 »

Note
Aluminum foil (or aluminum foil), often referred to with the misnomer tin foil, is aluminum prepared in thin metal leaves with a thickness less than 0.2 mm (7.9 mils); thinner gauges down to 6 micrometres (0.24 mils) are also commonly used. ... The foil is pliable, and can be readily bent or wrapped around objects.

In the process of making this , there are 2 sheets and they run through a roller press to get thinner and thinner. This process creates heat and often a coolant is applied. The coolants usually are a proprietary material. When you look at the metal foil you will see a shiny side and a matte side. The shiny side is the roller side so you may want to also experiment is one side is better than the other because of coolant residue.

Also Aluminum may react with the ammonia so another variable to consider. I only use stainless steel as it is inert against chemicals we use.
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Cbstark46143
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Joined: Sat Aug 30, 2014 5:49 pm

Re: Bending wildly curly wood

Post by Cbstark46143 »

So, when is it appropriate to use Super Soft 2?
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