side bending

[Tmh]

Just finished my first from scratch (3 previous kits) a slope shouldered 12 fret based on a j 45. A great learning experience. Had trouble with the sides cupping but used them anyway. I modified my bending mold by covering it with aluminum sheeting and tried a set of mahogany sides. mold,dampened side wrapped in kraft paper,slat,heating blanket,slat. first side cracked once in upper twice in lower. Tried other side and used magnetic woodstove thermometer to 300 f. went slow and results were worse than first attempt. Any ideas? Ditch the aluminum on the mold.Thought I had it warm enough. Sides were between 95 and 100 thous.
Any input appreciated.
Tim

[tippie53]

First the sides are too thick.
2nd you may be waiting foo long.
can you post a pic of your bending unit .
3rd the thermometer is measuring outside heat not inside.

So my basic bending is this
patter - slat - wet kraft paper - wood ( .075 to .090 inch thick ) wet paper - heat blanket - top slat.

Adjust into the bender , set the hold downs and turn on the blanker. I use a 5 watts per inch. Thermometer is under the top slat and against the blanket. I have found that you will get mis readings as the steam comes out . At 220 F I start to bend , lower bout first
check to see upper bout is damp and bend
drive waist cawl down
should be finished within 4 minutes to get the wood on the pattern

allow heat to set the bend and go to 325F to 375 F
once heat is attained set the controller to VAR and L setting . You want to be around 212 to steam out the last of the water. The heat process is total of 15 min then let cool.

[Tmh]

Thanks for the quick reply. I double checked my side thickness and it is in fact .100 The first set that I bent on this bender were thinner approx. .085 but I experienced cupping side to side so I left these thicker. Do you have any thoughts about using the mold with the aluminum skin (.035) or should i go back to the steel tubing spacers? Also my blanket is 6" x 36" and 540 watts. My bender is shop made from plans I purchased.
Thanks again Tim

[tippie53]

Aluminum is too weak to supply support. I would also ask to see the wood. Sometimes rift cut will cup. Glad to help

[Tmh]

I just wanted to let you know that the aluminum skin was over the existing mold with the cross bracing pipes intact. Seemed very strong. I just thought it would possibly cup less and eliminate one slat. The wood I used was not of the highest quality but until I gain some more experience bending I thought it would be the way to go. Maybe not?

Thanks Tim

[tippie53]

that doesn't look too bad , from the picture it looks pretty good .