Thanks Jimmy! The bender cost me about $45. The base is made of plywood I had on hand, 3 CERAMIC bulb bases, scrap lamp wire, a $15 sauna timer and a $10 dimmer. I use two 300 watt lightbulbs, one in each bout. I use a 150 watt bulb at the waist. I use duct sheet metal for the slats, one for over and one for under the wood. The form is removeable, and I built one for each size guitar....kinda rough, but the wood sort of follows its own curve if you get it close. The form is lined with tinfoil to keep from scorching the plywood.
I heat the form up with the slats clamped in until they sizzle when water is spritzed on them. On a cold day in the garage, this takes 15minutes, which is the length of the sauna timer anyway. While the form is heating up, I spritz the wood with water and wrap it in tinfoil to prevent scorching. I pull the heated slats out of the form and immediately sandwhich the wood in the hot slats, then put the assembly on the form,a nd turn the lights and timer back on. The slats have already heated the wood enough to bend the waste of a jumbo, which is deaper than a dread, so I clamp that down first. I push slowly down on the waist with a section of stair rail, then clamp it in position. Bending the lower bout of any shape guitar takes all of 10 seconds in this form, its such a gentle curve. Then I tackle the upper bout. On a standard guitar, I slowly bend this over about 2 minutes, as it is a tighter curve. Bending like this allows the heat fromthe bulbs to heat the rest of the wood, and there is some heat transfer up the slats and through the wood. When it is bent down, I clamp it in place, and reset the timer for 15 minutes. Steam should be escaping the whole duration. If not, I turn the dimmer down a bit to prevent scorching, but keep it heated for 15 minutes. I then take the form off the base, and let the side cool in the form. Once cold to the tuch (20-45 minutes, depending onthe wood and the weather), I pull it out of the form.....no springback!
The cutaways are tougher....I use the same sort of clamp at the cutaway I use on the waist, but it is a LOT tougher. I need to design some sort of crank system with a more form fitting caul. Its a biznitch, but it works. I have really grown to like the cutaways, though, so I need to build a more proffessional form. I'll wait until I get more scrap plywood form the boat building...I have enough sides bent right now for 5 gutiars....2-3 years of building at the current rate.
The thickness sander does not have an infeed table. Is it possible onthe one you had you were too aggressive? I can only remove about .010" at a time or it bogs down. I also get some pulsing, but if I run each one through twice reversing the wood between passes, there are no waves on the finished peice. It is slow and inefficient, but I only build one or two guitars a year. I spent a week thickness sanding enough wood for 12 guitars, and it is drying stickered in my house (3 years now,,,I have some zebra, flamed maple, padauk, and curly mango, as well as some sitka). When I get to this point on a boat, I will be planking the outer layer with mahogany, which I have very successfully planed down to about 1/8" with a 13" power planer I have...will go much quicker. Not even sure its worth the effort to go through a thickness sander with all the surface sanding I will have to do after its glued on....getting all the joints flush and sanding the epoxy from the edge-glued squeeze-out. I'll just have to remove the first and last 3" due to sniping from the planer, and the rest of the planer marks will get sanded off in hull prep.
I am excited to see yours coming along I still have no idea how the zebra will sound. I am using my own design of laminated braces too, which will have an impact. THe Padauk you've already seen sounds wonderfull withthe braces, but I am concerned about some structural isses...bridge keeps rotating. I might have been too aggressive with scalloping. Anyway, keep it up!
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Ken Hundley
http://www.nocturnalguitars.comSo, my big brother was playing guitar and I figured I'd try it too.
- Stevie Ray Vaughan
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