Thanks Jim. I'll send you a PM. I was hoping that I wouldn't have to go that route. But knowing there is another side eases the tension.
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| Crack While Straightening a Bend - Where to from here? http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=29583 |
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| Author: | John Killin [ Thu Oct 21, 2010 12:51 pm ] |
| Post subject: | Crack While Straightening a Bend - Where to from here? |
I started my first attempt at Pipe bending on real (not scrap) guitar wood and have bent myself into a bit of an issue. I am using a homemade charcoal starter bender. I’m bending the sides for a L-00 out of Hondouran Rosewood. The wood has been thinknessed to .080. I had a line drawn for the waist but as I bent the bend end up about an inch closer towards the lower bout. This made the side too short to work with the lower bout. I decided that I would try and straighten the bend and move it closer to the correct position. For the most part the straightening process was working fairly well. When I bent the “original” waist, I notices a hint of a line that formed. I’m not sure if this was on the inside or on the outside of the bend. I was using a piece of flashing to provide support during the bend. Right were this line was (I’m now thinking it was the start of a crack instead of a burn) I had trouble getting the side to straighten out. The bend was coming out on either side but left a peak at the line. Attachment: Side Peak.jpg I tired to remove the peak and now have the start of tearing fibers showing in the waist bend. There is a line on the other side of the crack. At this point the side seams solid. If I try and flex it, it holds its shape and doesn’t feel as though it is going to break. The problem is that this peak (and now crack) hits the body side right in the straight part coming out of the waist bend. Below are some picks of the crack. I have the green tape marking where the waist should have been. I was thinking of flooding the crack with CA once I was done working with it, but need some tips on getting this part flat. The burning you see happened while I was trying to straighten the bend. I only had some light scorching while I was actually bending. Attachment: Waist and Crack.jpg Attachment: Inside Crack line.jpg Attachment: waist and Crack 2.jpg Thanks for the tips, John |
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| Author: | JimWomack [ Thu Oct 21, 2010 1:25 pm ] |
| Post subject: | Re: Crack While Straightening a Bend - Where to from here? |
Bummer, John. That kind of crack would be tough to fix. Be easier to just start with a new side. I've got a couple of extras from the same billet yours came from. PM me your address and I'll get you a new one. |
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| Author: | John Killin [ Thu Oct 21, 2010 2:01 pm ] |
| Post subject: | Re: Crack While Straightening a Bend - Where to from here? |
Thanks Jim. I'll send you a PM. I was hoping that I wouldn't have to go that route. But knowing there is another side eases the tension.
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| Author: | Alexandru Marian [ Thu Oct 21, 2010 2:10 pm ] |
| Post subject: | Re: Crack While Straightening a Bend - Where to from here? |
Thin the next one more. Honduras is very dense, go down to .07 and will it bend a LOT easier. |
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| Author: | Chris aka Sniggly [ Thu Oct 21, 2010 2:40 pm ] |
| Post subject: | Re: Crack While Straightening a Bend - Where to from here? |
Wooooooow. I did that too!....and then I went  !!Just get another dude. In my opinion it's not worth fixing. Headstock overlays for the rest of it! |
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| Author: | John Killin [ Thu Oct 21, 2010 2:50 pm ] |
| Post subject: | Re: Crack While Straightening a Bend - Where to from here? |
I know it doesn't look, good but at least I made some progress. I have now started working on something other than a jig. Really even with the setback this is big progress for me. |
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| Author: | Laurent Brondel [ Thu Oct 21, 2010 3:27 pm ] |
| Post subject: | Re: Crack While Straightening a Bend - Where to from here? |
Honduran RW bends like butter. As Alexandru points out, .070" should be easier (and lighter…). However it looks like the pipe was too hot, too long. On the pipe you have to keep moving back and forth, adding moisture eventually if it gets too dry. You'll feel when the wood is letting go, then stop moving and start the bend. Do not wait until the wood gets case hardened, and even charred in your case. A crack across the grain is virtually impossible to fix and hide. |
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| Author: | John Killin [ Thu Oct 21, 2010 3:57 pm ] |
| Post subject: | Re: Crack While Straightening a Bend - Where to from here? |
Most of the burning happened when I was trying to get the kink out. Originally I had worried because it was taking longer to release than the scrap wood I had bent. I did increase the temperature on the pipe towards the end. I probably need to give the pipe more time to warm up as well. Then make sure the temperature is stable and not creeping up. I have a lot to learn. |
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| Author: | Rod True [ Thu Oct 21, 2010 4:26 pm ] |
| Post subject: | Re: Crack While Straightening a Bend - Where to from here? |
And here in lies a very good example of why so many use a fox style bender and heating blanket 
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| Author: | Mike OMelia [ Thu Oct 21, 2010 4:56 pm ] |
| Post subject: | Re: Crack While Straightening a Bend - Where to from here? |
I wanna second Laurent... that wood is burnt (or is it burned???). Anyways you can clearly see it and burnt wood will just crack. I also want to second Rod. You can build a fox bender for under $100. Use the lightbulbs until you can justify the expense of the blanket. Ask questions about the fox bender because a lot of the cost can be minimized if you know what not to include (from the drawings) (eg, the aluminum caul). That said, the blanket sure is nice! I started with the Fox Bender, and experimented with a hot pipe (iron pipe from lowes with a propane torch to heat it). With that much heat, water spritzing is really important. Mike |
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| Author: | John Killin [ Thu Oct 21, 2010 7:32 pm ] |
| Post subject: | Re: Crack While Straightening a Bend - Where to from here? |
One of the stupid things is that I have a bender that I have built. I just don't have the blanket and haven't made a form for this size. I wanted to try and do at least one with a pipe... just to have done it. It seemed like a good idea at the time. I also didn't use much water. I sprayed the sides with a spray bottle. But defiantly didn't over do it. I over did the water on my first bend of some Koa uke sides and had some cupping in a uke size light bulb bender. So.... 1. I had the pipe to hot and didn't move the wood enough. 2. Could use more water. 3. Thinner will bend easier. 4. The bender I have sitting on the floor next to where I was using the pipe has tons of potential. |
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| Author: | alan stassforth [ Fri Oct 22, 2010 1:01 am ] |
| Post subject: | Re: Crack While Straightening a Bend - Where to from here? |
The last time I bent sides on my hot pipe, which is still all I have at this point, I put a moistened terry rag over it, and it worked good for me. I will build some kind of bending jig for the next build, because I'm sick of the time I spend bending wit da pipe. |
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