Official Luthiers Forum!

Just got a heating blanket fron John Hall. I've used the old light bulb heat source since "last century" but got the blanket to do a cutaway bend on two sets of "The Tree" mahogany. Figured a more even heat source/distribution will lower the "Oh No!" factor when bending this highly figured, and expensive, wood.

So...I need some temperature guidelines from you who use the blanket heating system, and any hints you may have gathered in your bending experiences with a blanket.

I've got the variable power switch and figure to run it through the timer on my Fox bender just as an extra precaution.

So, what temps worked for you?


Thanks,
Hank

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Hank Mauel

Venitian?
Think about using Super Soft.
Heat to 230, start setting the waist slowly, leaving about 1/2" gap.
As it moves up to 250, slowly do the lower bout. Set the waist the final 1/2"
At 250 slowly set the cutaway as it climbs to 300.
Let it stay at 300 for 5 minutes.
Turn off. Let sit over night.

Wrap in paper, lightly spray water on both sides.
Put blanket on top, check that the more dimpled side of the blanket is away from the wood.
Verify you thermometer's output before you start.

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

Hank!...I also have the same combination of blanket and bulbs and really believe the dual source helps with the bend. I typically measure the top surface of the blanket with a StuMac surface thermometer as a guide. I mostly start the bend when it approaches 200*F and turn off the heat upon reaching 300*-315*. In order to achieve those temps, I typically have the blanket dialed in the center of the "medium" territory of the controller.

Hope this helps...good to see you back!

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JJ
Napa, CA
http://www.DonohueGuitars.com

Yes, Venetian...unless it cracks, then pointed!

So, you set your waist BEFORE any of the cutaway bending. On less figured woods, with the "light system" I set the waist, then backed it off a bit, did the cutaway, then reset the waist to final depth.
Are you using "cooking" parchment paper?

Thanks for the heat/time schedule.

Hank

_________________
Hank Mauel

The Tree!!!! A good sedative is recommended.......

I was thinking of some chips, salsa and a pitcher of margueritas.
Not necessarily in that order!

_________________
Hank Mauel

Hank,
I have a roll of white 36" drafting paper. It was just sitting around and free.

_________________
"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.