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| Trouble bending sapele http://luthiersforum.com/forum/viewtopic.php?f=10101&t=47627 |
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| Author: | Pete0530 [ Wed Apr 13, 2016 4:14 pm ] |
| Post subject: | Trouble bending sapele |
Hi Everyone! Hoping to get some direction on bending sapele sides for a parlour guitar. I have built quite a few of these guitars using EIR, mahogany, maple and sycamore with little trouble, however, sapele is an entirely new adventure! For some reason, no matter what I do I can't avoid major spring back. The wood itself is quite unremarkable, well quartered without much figure. No extreme curves required. It is thicknessed to 0.075''. I started out on the sidebender, lightly spritized with water and wrapped in foil taking it to 310F with a heating blanket and holding it there for 10 minutes. Tried going a little hotter, but there was evidence of scorching. Once it cooled it became obvious that it wasn't there yet so put it through a couple more of the above mentioned cycles. Still way too much spring back! Tried touching it up on the bending iron, but it is very unresponsive. Just prior to this bent a couple of highly figured maple sides using the same approach without difficulty. What's going on? Suggestions? Thanks in advance! |
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| Author: | Michaeldc [ Wed Apr 13, 2016 6:23 pm ] |
| Post subject: | Re: Trouble bending sapele |
Hi Pete, I feel your pain... I bend my sapele at a max temp of 330°, then lower temp to 280° and cook for 20 minutes. I let it come down to room temp and run it back up to 330° for for a less than a minute, then back down to 280° for 20 minutes. 3-4 cycles does the trick. I then get it in the mold immediately. Works for me with no scorching. I should add: I use stainless slats from Blues creek and dampened parchment instead of foil |
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| Author: | patch [ Thu Apr 14, 2016 1:14 am ] |
| Post subject: | Re: Trouble bending sapele |
Hi, I’ve bent 10 Sapele sides so far with out much trouble. What I’ve been doing is soaking the side for maybe 15 - 20 minutes then wrap the side in paper cut up from a shopping bag then soak again getting to get the paper wet. I then wrap all that in foil and stick it in the bender with the slates and blanket. I’m not sure exactly what temperatures I’m getting, I use a variable router dial and a grill thermometer, not precise but it’s worked fine for 19 sets so far. Anyway I go by steam and sound. When the side goes quiet I turn off the heat and wait a few hours before I take the side out and put it in the mold. So far this method has worked well. I think the key differences are maybe soaking instead of spritzing and leaving the side to dry in the bender not just cool. Hope this helps, good luck! |
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| Author: | kencierp [ Thu Apr 14, 2016 7:46 am ] |
| Post subject: | Re: Trouble bending sapele |
Whether you have bent 10 or 19 sets? I really find this process interesting and rather surprising. My experience with Ribbon figure Sapele has been the less water the better. Because of the interlacing cross grain feature of Sapele water causes the thin wood to cup and ripple almost instantly preventing any bending at all. Frankly, I agree bending Sapele can be an adventure -- Bob Taylor has stated it is the most difficult even in his hi-tech factory environment. |
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| Author: | bluescreek [ Thu Apr 14, 2016 7:53 am ] |
| Post subject: | Re: Trouble bending sapele |
Agree less water more heat. I allow the heat to hit 375 to set the bends. Too much water can make it cup and warp too little can cross grain fracture. The more figure the more of a challenge. It is also a funny wood in that one side may bend well and the other will drive you nuts. |
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| Author: | klooker [ Thu Apr 14, 2016 8:09 am ] |
| Post subject: | Re: Trouble bending sapele |
I've only made 1 Sapele guitar but I broke 2 sides in the bending process. My problem was getting enough heat into the wood without scorching it. Making sure the heat blanket/slat/wood had good solid contact solved my problem but there was still a lot of spring back. I can see how extra moisture would help get more heat in but then you have to deal with that extra moisture. |
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| Author: | kencierp [ Thu Apr 14, 2016 9:10 am ] |
| Post subject: | Re: Trouble bending sapele |
Quote: My problem was getting enough heat into the wood without scorching it. I found that wrapping the side is white parchment paper (grocery store baking supplies) is helpful at higher temps. |
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| Author: | patch [ Thu Apr 14, 2016 10:33 am ] |
| Post subject: | Re: Trouble bending sapele |
kencierp wrote: Whether you have bent 10 or 19 sets? I really find this process interesting and rather surprising. My experience with Ribbon figure Sapele has been the less water the better. Because of the interlacing cross grain feature of Sapele water causes the thin wood to cup and ripple almost instantly preventing any bending at all. Frankly, I agree bending Sapele can be an adventure -- Bob Taylor has stated it is the most difficult even in his hi-tech factory environment. I've bent 10 Sapele and the rest have been a handful of other types. The OP was talking about Sapele without much figure, which is what I have been bending. Seems to me anything with figure gets much tricker so I use less water but still have wrapped in a wet paper bag then foil. Maybe I've been lucky with the Sapele so far, I don't know, I'm just sharing what I've done. |
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| Author: | Pete0530 [ Fri Apr 15, 2016 12:48 pm ] |
| Post subject: | Re: Trouble bending sapele |
Thanks everybody. Lots to consider! |
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| Author: | Terence Kennedy [ Fri Apr 15, 2016 6:07 pm ] |
| Post subject: | Re: Trouble bending sapele |
One option if you expect trouble with a particular wood is to do double sides. You can bend at .060 or .050 and with all our other little helpers like super soft, damp wrapping paper, proper bend sequence and slat thickness, maybe two blankets, it goes well and much less chance of a break. You can bend both sides at the same time. My first double side guitar was done for that reason, I had some expensive Koa a guy gave me and I was scared to death of breaking it. It went well and I liked the way it sounded so much I do double sides all the time now. It's especially nice on archtops with a tight cutaway. |
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| Author: | Joe Beaver [ Sat Apr 16, 2016 2:08 pm ] |
| Post subject: | Re: Trouble bending sapele |
My first adventure with sapele was a difficult one. I broke several sides before I got it figured out. Since you don't seem to be breaking yours then you are far ahead of where I started. When bending none figured sapele I came to the conclusion that the wood went from hot enough to bend to brittle in a very short time. My success went way up (no breaks or scorching and only moderate springback) when I started doing it like this. I spray the sides lightly and then lay paper on them, spray again giving the paper a good wetting but no standing water. Then I cover with aluminum foil, add blanket and slats and put it on the bender. I should add that I put the blanket on the bottom so it does not heat up the upper and lower bout until I am ready for them. I heat it up and start with the waist. When I have a good sizzle going (around 250+ degrees) I press the waist slowly into place and turn the blanket off. I spray water onto the waist to cool it. Then I pull the blanket up to the lower bout and clip it to make good contact. Turn the blanket on and bent when hot. Once the bout is in place turn the blanket off and cool with the water then repeat with the upper bout. For the whole process I set the blanket for 305 degrees. |
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