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| Those who use two heating blankets when bending... http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=38643 |
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| Author: | CharlieT [ Sun Dec 23, 2012 6:29 pm ] |
| Post subject: | Those who use two heating blankets when bending... |
How many of those who use a Fox style bender use two blankets rather than just one? Do you find two blankets makes a significant difference? Also, does the added thickness of the additional blanket alter the shape of the bent sides to any noticeable degree? Do you need to factor it into the shape of your forms, or do you find that unnecessary? Thanks! |
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| Author: | Josh H [ Sun Dec 23, 2012 11:27 pm ] |
| Post subject: | Re: Those who use two heating blankets when bending... |
Hi Charlie, I'm guessing there are not many of us that use 2 blankets but I am one of them. I don't know if I'm the best person to answer your question since when I switched to the Fox style bender I started with 2 blankets. So I can't offer a good comparision to what it is like to use 1 blanket. I believe it was John Mayes who I first heard recommend using 2. In my mind it is not absolutely necessary to have 2 blankets (obviously most people dont'), but I believe that it is a benefit to heat both sides of wood while bending. I have never broken a set of wood using 2 blankets. I've had one or two pieces crack, but they were salvageable. I think that is pretty good since I've put 50+ sets of sides through it since buying it 4 years ago. I made all my bending forms and did take in the thickness of the blanket into account when making the forms. I should also mention that I don't do cutaways on the bender. I either bend those by hand or do Florentine cutaways. Josh |
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| Author: | Joe Beaver [ Mon Dec 24, 2012 12:20 am ] |
| Post subject: | Re: Those who use two heating blankets when bending... |
I use two blankets but in a different way than Josh. I use one full lenght blanket and a small one just in the waist area. I heat the small one only and bend the waist then unplug that one and heat the 36" blanket and bend the bouts. It works pretty well helping me to avoid scorches in the waist area. |
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| Author: | Terence Kennedy [ Mon Dec 24, 2012 10:17 am ] |
| Post subject: | Re: Those who use two heating blankets when bending... |
I switched to two full length blankets around 5 years ago also because of John Mayes. Have not broken or cracked a side since in probably around 35 instruments. I did not make any adjustments to my bending forms as I used the blanket on the bottom when I was using one. |
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| Author: | CharlieT [ Mon Dec 24, 2012 12:17 pm ] |
| Post subject: | Re: Those who use two heating blankets when bending... |
Thanks for the info, guys. Much appreciated. Josh - did you use CAD to adjust your forms for the thickness of the blanket? |
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| Author: | Link Van Cleave [ Tue Dec 25, 2012 1:04 pm ] |
| Post subject: | Re: Those who use two heating blankets when bending... |
CAD ? Get a rabbiting bit. If you don't have a template of your bending mold make one with a flush cutting bit and some 1/4" mdf. Take the rabbiting bit and change the bearing so that it is cutting a 1/8" rabbit. Make a new template (from the one you just made) with the 1/8" rabbit. You now have a template which is 1/8" smaller and you can make another mold or modify your old one. With a 2" bearing on top bit you can cut from each side of your old mold and have only a 2" area in the middle to clean up. Or if making a new one you can route as you go and do the whole thing. In that case you have to switch to a bearing on top bit after the fist or second piece of 3/4" ply. L. |
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| Author: | CharlieT [ Tue Dec 25, 2012 8:15 pm ] |
| Post subject: | Re: Those who use two heating blankets when bending... |
Todd Stock wrote: I bought a couple nylon spacers at Lowes...wall thicknesses between about .063 and .120, including the .100 that is side thickness plus slat plus foil and paper...gives me an offset outline. I make the body template first, use it to make the outside mold, then make the inside mold pattern using the spacer for the correct offset. Todd, that's brilliant. Thanks for sharing that. |
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| Author: | CharlieT [ Tue Dec 25, 2012 8:17 pm ] |
| Post subject: | Re: Those who use two heating blankets when bending... |
Link - that's a great idea. Thank you! By CAD, I meant a computer aided design software (Rhino in my case). The methods you and Todd describe make more sense though. |
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| Author: | Josh H [ Wed Dec 26, 2012 11:38 am ] |
| Post subject: | Re: Those who use two heating blankets when bending... |
Hey Charlie, I did like Todd only started with the mold and then made the bending forms. CAD and CNC is a great way to make forms if you have it. But I made my bending forms with a bandsaw and edge sander a lot quicker than if I'd done it on CNC. I didn't have CNC at the time I made most of my bending forms, but I do now. Josh |
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| Author: | CharlieT [ Wed Dec 26, 2012 12:10 pm ] |
| Post subject: | Re: Those who use two heating blankets when bending... |
Thanks Josh. The method you guys describe will work great for my needs. |
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| Author: | Ed Haney [ Wed Dec 26, 2012 12:46 pm ] |
| Post subject: | Re: Those who use two heating blankets when bending... |
CharlieT wrote: Do you find two blankets makes a significant difference? Also, does the added thickness of the additional blanket alter the shape of the bent sides to any noticeable degree? Do you need to factor it into the shape of your forms, or do you find that unnecessary? I have 2 blankets that are the same and plan to try them both together, but have yet to try it. Intuitively I think heating at the same rate on each side would be an advantage for even heating and heating on the inside of all curves. But I do not expect the advantages to be "significant". Is it "necessary" to adjust the forms for the thickness of the blanket? No. But it is an advantage to do so and it is easy to do. |
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