Official Luthiers Forum!

OK. Just started bending my first sides on a fox style bender that I made. I got 6 maple practice sides from Stew-Mac and basically tried to duplicate what Todd Stock does on his bending videos (Thanks Todd). Me, being in a hurry, cooked the sides for about 40 minutes between 300-340, let it cool down to room temperature and anxiously took the sandwich apart to see what I had done. And Waa-Laa! I had actually bent a side! Now as you can see in the photo there was spring-back, but still I was pretty happy. But I decided that I wanted to tweak the spring-back out of the side using a hand-bending iron. I basically used Stew-Mac's directions on the hand bending technique, just knowing that I was about to make the perfect side. Well, not only did I not get rid of the spring-back, I actually made it worse! Not only that, but I cracked the lower bout as well (see photo).
Please have mercy on me. Can anyone tell me what in the heck I did that actually made the side spring-back even more? I am now totally confused.
Here are my questions:
1. What did I do during the hand bending that would make the side spring-back more?
2. If I just heatblanket bend only, what can I do to minimize spring-back.
3. What is an acceptable amount of spring-back?

Thanks for listening to my problem and much thanks in advance for any help.
Bill

i cant give much advice but in john mayes video he has a over bend on the " horse's "
on both ends allready so you dont run into that problem sorry i cant be of more help

I cut my mold to handle springback about an inch back and 1/2" front. Maple is not the easiest wood to bend. Your probably heating out the bend when you reheat it, maybe not enough water, not hot enough??

How thick were your sides?

Nice molds BTW...

_________________
Here is what a Parlor Guitar is for!
http://www.youtube.com/watch?v=oEa8PkjO6_I

During the hand bending part did you hold the sides in position while they cooled?

_________________
Jim Watts
http://jameswattsguitars.com

As you are finding out , bending is a skill. I use a 15 minute drying time after heating but regardless of the length of time I use a 200 to 250 temp cycle to dry off the side and as Todd points out ,your wood has to be cool. Maple doesn't like a lot of water but you need to use enough so you can get through the bend cycle before you case harden the wood. The next point I will ask is how you actually bent them ? Do you do the bouts and then the waist , or did you start at the waist. I found doing the waist last gets you a better repeatability and shape. What was your thickness of the sides ?
My bending method is similar to Todd's and I doubt the differences between our methods are really that different. His video is well worth the time. Practice and it won't take you long to succeed. remember that if you are using a building mold just getting it close is all you need. I do compensate my form for spring back.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Thanks everyone for the help. I was gone all day and just now got back to the computer.

Todd - This time I let the side set overnight before taking it out of the form and the spring-back was minimal.
John - Yes, I use your method of lower bout, upper bout and final tightening of the waist. It works great!

My only problem now is that I scorched the maple rather badly. Do you think it was my drying temperature (varied between 300-340 for 40 minutes)?

John, I just now noticed that you said you dried at between 200-250. Would this be a better drying range for maple and most other woods, or does that vary from species to species?

I had a hard time getting my hand bending iron up to 300. I"m thinking that maybe I was trying to bend at too low of a temperature even though I saw steam coming off (Like Todd said). Would most of you think that 350-400 would be better on the bending iron? How long should it take for the iron to get up to 350? More than 30 minutes? It seemed like it wasn't going to get there.

Once again, thanks everybody. (Sorry for the random questions)
Bill

_________________
Formerly know as Mandodiddle.