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| "Feel" for bending on a Fox bender http://luthiersforum.com/forum/viewtopic.php?f=10101&t=39052 |
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| Author: | tjp [ Mon Jan 21, 2013 10:46 pm ] |
| Post subject: | "Feel" for bending on a Fox bender |
Hi everyone, apologize if this has been covered before. I've just about finished my fox-style bender and about ready to bend my first sides (Otterhound's Black Walnut). How do I feel when the sides are ready to bend? When I bend bindings on a pipe, I can feel the wood give. Pretty sure that's not going to happen on the bender. How's it work? Do I just take it to temp and crank on it and cross my fingers? Will I be able to feel it relax with slats and all? |
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| Author: | WaddyThomson [ Mon Jan 21, 2013 10:58 pm ] |
| Post subject: | Re: "Feel" for bending on a Fox bender |
It's a very different thing when using a blanket. The whole piece of wood it already hot, as the blanket is sitting nearly right on it, with maybe a layer of Kraft paper and a layer of foil. If you spray the Kraft paper with water before layering on the wood, when you start seeing steam production, you can start the bend at the waist. Take it down to about 1/2" from being tight down (this keeps it in pllace) then pull the lower bout spring slider, then the upper bout slider, then pull the waist tight. Bend done in less than 7 minutes. I really suggest watching John Hall's videos & Todd Stock's on You Tube. I don't have a Fox bender, but this is what I did recently on my first attempt with a blanket. I just used clamps to puil the center caul down, then hand bent the bouts using a piece of 2x4 as a slide, clamped them in place, then tightened down the waist. It happened very fast. I was getting significant steam within a couple of minutes and the temp was reading about 250 at the wood when I started the bending. I worked pretty fast, and the whole thing was complete in under 10 minutes, so I let it cook to about 350 or so and cut it off and let it cool. After a couple of hours I re-cooked to about 300 or so, then let it cool again. No spring-back at all. |
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| Author: | tjp [ Tue Jan 22, 2013 12:19 am ] |
| Post subject: | Re: "Feel" for bending on a Fox bender |
Thanks for the reply - I thought about your method, actually. But it was pretty easy to buy some springs and a couple chunks of all-thread rod. It sounds like I wait til it's to temp, and crank away. I've seen the videos, and that's what it looked like. Will look at them again before I bend, it just gives me the willies a bit to not be able to feel when it's ready. I'm sure it will be a matter of experience. |
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| Author: | Joe Beaver [ Tue Jan 22, 2013 3:56 am ] |
| Post subject: | Re: "Feel" for bending on a Fox bender |
I think heat control and time of bend are the key. I recently added a LMI temp controller. It has improved my bending success considerably. I prepar my sides pretty much as Todd Stock indicates in his video. Except I do tend to bend a little thicker (.92-.95) I set the controller for about 305 degrees and start the waist at 250. by the time it has reached 300 it is fully in the waist. Since I use the waist blanket and a full sized one, I unplug the waist and plug the main one in as soon as the waist is bent. When it reaches 250 I start the lower bout, finish it 2/3's of the way then do the upper bout about 2/3's of the way. Then I finish the lower and then the upper. Some times the thermocoupler doesn't make good contact so you have to watch for steam also. If it seems like it should be hot but the temp is still low I look for steam, listen for sizzle, and sometimes put a few drops of water here and there to check. To hot means scorched wood. To cold means cracks. |
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| Author: | SteveT [ Tue Jan 22, 2013 9:20 am ] |
| Post subject: | Re: "Feel" for bending on a Fox bender |
I hang several large spring clamps to the blanket sandwich at the tail end of the lower bout. This provides enough weight so that when the wood softens, it starts to bend itself. That's when I know it's time to take action. Of course, I also use a thermometer. |
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| Author: | ChuckH [ Tue Jan 22, 2013 11:36 pm ] |
| Post subject: | "Feel" for bending on a Fox bender |
Just finished bending maple binding with purfling glued on with LMI white glue. Started bending at 245 deg and then lower bout first then upper bout at 305 deg. Let sir at temp a few minutes till all the water cooked out then shut off. Cooled for approx 45 minutes and turned out perfect. I use two blankets. Sent from my iPhone using Tapatalk |
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| Author: | Terence Kennedy [ Wed Jan 23, 2013 12:46 am ] |
| Post subject: | Re: "Feel" for bending on a Fox bender |
Lots of good stuff out there to check out, John Mayes videos, John Hall and Todd Stock tutorials. The moist brown wrapping paper trick is huge, I use two blankets like Chuck. Clamp up the sandwich with spring clamps for even heating. As far as feel, when the steam really starts rolling off (usually around 270 or so) bring the waist down halfway, then bend the lower and then the upper bout, all slow and steady, and finally bring the waist down all the way. The waist is a lot better supported if you bend the bouts first. You are usually around 325 or so by that point. Whole process is usually under two or three minutes once you start bending. I usually cook it around 300 for 10", let it cool fully and cook it again. (for a side, just once for binding.) Fully cool and out to the mold. A million other ways but this works OK for me. |
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| Author: | murrmac [ Wed Jan 23, 2013 9:14 am ] |
| Post subject: | Re: "Feel" for bending on a Fox bender |
since we're referencing side-bending videos, it would be only fair to give a mention to Mario's 3 minute tour de force... |
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| Author: | Glen H [ Wed Jan 23, 2013 10:11 am ] |
| Post subject: | Re: "Feel" for bending on a Fox bender |
Quote: Pretty sure that's not going to happen on the bender You can tell on a fox bender also. When I see the ends of the side start to droop by their own weight, I begin the bending. |
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| Author: | WaddyThomson [ Wed Jan 23, 2013 10:58 am ] |
| Post subject: | Re: "Feel" for bending on a Fox bender |
murrmac wrote: since we're referencing side-bending videos, it would be only fair to give a mention to Mario's 3 minute tour de force... I didn't mention that one, but + 1. |
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| Author: | Tom West [ Wed Jan 23, 2013 11:19 am ] |
| Post subject: | Re: "Feel" for bending on a Fox bender |
In Mario's video the actual time from when he places the wood in the bender till he says he is happy is 1 minute and 40 seconds. Very impressive to say the least.....!!! Tom |
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| Author: | tjp [ Wed Jan 23, 2013 11:33 am ] |
| Post subject: | Re: "Feel" for bending on a Fox bender |
Wow, thank you all! Spent about half an hour looking at videos last night, I'm feeling much more confident now. |
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