Quick Bending Questions.

[Gilbert Fredrickson]

Flamed Big Leaf Maple sides wrapped in foil, .078, using a heating blanket. Dry or light spritz? How hot? Figured Narra (.078) with pin-knot cluster in lower bout area, using heating blanket, foil, aluminium slats. Dry, or light spritz?

[Gordon Bellerose]

I'm about to embark on my first acoustic build, and this info would be great for me also.
I hope someone can enlighten us.

[Michael Lewis]

Big leaf maple will want a good spritz, and put it on the side you put the blanket. It probably doesn't really matter much as long as it is encased in foil. I put metal slats on both sides and the blanket on the inside, clamp the 'sandwich" (metal, blanket, foil wrapped side, metal) together with spring clamps temporarily until 'steam' starts to escape the ends of the foil, THEN begin your bending. You will need some gloves.

[Gilbert Fredrickson]

Thanks. I broke a Khaya side and now I am "gun shy" with my figuired woods. In fact, I've been shooting and joining tops and backs, sorting stock, pretty much everything but bending wood. I have a pair of Khaya replacement sides thinned to .075" and I'm just not ready to bend them. I think I'll go with the damp brown paper in the tin foil wrap, sandwiched (with the blanket on top of the tin foil and wood) between the bending slats. So ...heat on high till there is steam, turn the router control down to med-hi, bend the waist half way, bend the lower bout, tighten the waist down, bend the upper bout slowly. It's the bend between the waist and the upper bout that had buckled. The horror ...the horror.

The whole process should be about four minutes. I guess I had just become cavelier with the sucess of the Rosewoods and Sapeles and, of course, the plain Maples. My freehand bending on the pipe is good, just not real accurate.

[Michael Lewis]

You can always bend by hand and then do any corrections in your body form with the blanket and slats. Also, get some other material with which to practice your bending skills.

Everyone's shop is a different 'kitchen' where recipes can turn out differently, so when someone suggests to do something a certain way remember there are variables involved.

[Nick Dingle]

I'[ve only ever bent by hand, and find it gives me a real "feel" for the wood. It bends when it wants to bend and not before. Last set I did was Bubinga, wich is supposed to be a tough bend, but with a spritz and a bit of time, it bent very nicely.

So, I guess, I second the idea to bend it first by hand and then use the blanket and form to finish up. It'll give you a good appreciation for the particular timber you have....Bending is my favourite part. While you've been joining plates, I've been bending sides. Four sets in moulds at the moment...

[Warren May]

Great advice, thanks for sharing your experiences. Any advice on bending Wenge?

[Clay Schaeffer]

" Any advice on bending Wenge?"

Use a piece of sheet metal or a side bending strap to support the wood while bending. Wenge likes to split along the grain pretty easily.

[Mario Proulx]

I think I'll go with the damp brown paper in the tin foil wrap, sandwiched (with the blanket on top of the tin foil and wood) between the bending slats.

There's your problem... Put the blanket -below- the wood.

Heat rises...

[Gilbert Fredrickson]

Viola! The blanket goes under the wood? This would work well with the compression bends in the upper and lower bouts, with the heat on the side of the bend that is being compressed. I have been using the blanket on top of the wood for the tight bend at the waist.

[Mario Proulx]

If you close-up the bender with the blanket in between the slats and get it good and hot before you introduce the wood, there will be enough heat left in the upper slat to execute the waist bend. Or, do the waist on a hot pipe, and finish the bends in the bender.

Edit:

Here's a video of how I do it...

http://youtu.be/sUJbB0pa7Zs

[Randy Roberts]

Hate to contradict but...
Heat radiates, it doesn't rise. Hot air rises due to it being less dense than cooler air, but heat doesn't rise. As long as there is good contact with the blanket and what's being heated, it doesn't matter if the blanket is on top or underneath.

[Mario Proulx]

Perfect contact cannot be assured...

At any rate, I have NOT broken a single rib with the above method. The OP, on the other hand....

[Gilbert Fredrickson]

Thanks all. Thank you, Mario, I am a fan of the pick guard material you developed. Thanks, John Hall at Blues Creek Guitars.

[Michael Lewis]

I choose to put the blanket on the inside of the sides because of possible scorching that I don't want on the outside where it can easily be seen.

Heat radiates, but in this case it 'conducts' through contact.

[Gilbert Fredrickson]

Great advice. Nice video. On the side I broke, I must have rushed it and not allowed the wood bend. It is a Zen thing, Grasshopper.