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PostPosted: Fri Apr 26, 2019 1:47 am 
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Joined: Sun Sep 09, 2018 12:23 pm
Posts: 15
Hi, I have been working to learn to bend and have some practice maple sides that are now 2.8mm thick and mostly ripped into longer strips and/or cross cut into shorter pieces. I have a 2" pipe set up and have tried a torch and a heat gun, both seem pretty hot and moist wood easily steams. I have been spritzing with water during bending. I have cracked every practice piece I have tried. I am able to get the wood heated and can feel some release and get some bending, but get a crack before getting to the final curve. I'm not sure how to trouble shoot this, how do I know if the pipe it too hot, not hot enough, the wood is too thick, too much or not enough water, too much pressure, wrong pipe diameter.....etc. There's a few variables and I"m not sure how to trouble shoot or adjust what I'm doing. Any advice would be a appreciated! Tnx.


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PostPosted: Fri Apr 26, 2019 1:55 am 
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Joined: Sun Sep 09, 2018 12:23 pm
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or using windex with ammonia? I have not been using a back metal sheet. Tnx.


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PostPosted: Fri Apr 26, 2019 9:02 am 
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Joined: Fri Mar 03, 2006 7:09 pm
Posts: 5846
Location: Hegins, Pa
that is too thick
go to 1.9 mm that will help
also you can use a steam iron to help get the wood soft then dry heat to set the bend. If you can set a piece of flexible metal to help press it , that may help the cracking. It is a thin line when working with figured wood to not get it to separate or crack.
Yes windex may help but you will see with Maple it like a bit less water and more heat. It take a bit of time but once you get the feel , you will understand when the wood is ready to bend.

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John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
Board of Directors of Association of Stringed Instrument Artisans
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PostPosted: Fri Apr 26, 2019 12:58 pm 
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Joined: Mon Jul 28, 2014 7:50 am
Posts: 658
Location: Chadds Ford, PA
One way to approach the bending problem, specifically is to consider bending veneer. Std veneer (~0.024") will, of course, bend cold and dry (not permanently). Putting dry veneer of a hot pipe will produce a permanent bend very quickly and rarely will separate or crack. Progressing up from there to 0.0625 requires good heating, spritzing helps and a little more effort. Similarly, bending at 0.125 takes good heating, lots of care and maybe a steam box to avoid cracking. The purpose of heating to loosen up the cross-linking hydrogen bonds in polymers of cellulose. Shipwrights like Ed can bend planks with a steam box. However, what John mentions in going to 1.9mm thickness is great advice and will boost your success significantly.


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PostPosted: Sun Apr 28, 2019 11:57 am 
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Joined: Sun Sep 09, 2018 12:23 pm
Posts: 15
Thanks for the advice! I had my pieces sanded down to 1.9mm and have had some success. I was able to pretty easily bend some 2" wide strips and could clearly feel the release in the wood when it was ready to bend. I was able to bend a set of 3" wide practice maple ukelele sides with just one small crack inside the waist which I patched over with a thin strip using CA. This set of sides took forever, probably 45 minutes each side. I never really did feel a full release in the wood, but more had to make very small incremental bends. Not sure if that is just variation in different wood pieces or why it behaved so different from the other strips? Anyways I'm happy with how they turned out and will use them for a build. Today will move onto the real wood for my actual build which is sapele. From what I read it should readily bend, and some people soak it for 10 minutes. I will try that or will just spritz.


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