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Hi everyone,

I just did it - I completed building my heat-blanket side bending machine today and just had to give it a go...tried a Wenge practice side. The bending itself went surprisingly well. The machine needs a few improvements though, so here are my questions:

The springs I used for the cauls are too weak. What size spring would you recommend?
Also, the lower bout lifted a little - would you recommend two cauls for the lower bout?

thanks a lot, Christian

oh, and also...how is Wenge to bend? I found it pretty easy, so I'd like to know where it lies on the spectrum.

you need a 3/4 heavy spring with .083 wire. 5 and 6 inches long. Also what was your bending procedure?

_________________
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

Yes, I felt pretty good being finally able to bend my first side. I also really enjoyed the process of laying out and constructing the bender.

Thanks for the spring sizes, John...I probably should have ordered those with the heat blanket

As to my procedure:
- Wet the sides a little (went with my guts as to the amount of water), wrap them in parchment paper, make the steel slat-wood-blanket-steel slat sandwich
- Heat the blanket up to about 220, then I started to tighten the waist a tiny bit (but nowhere near 1/2" from the form)
- set the lower bout, cursing after realizing the springs were to weak
- set the upper bout, even more cursing because those springs were even weaker
- set the waist (temperature now up to around 260)
- lowering the temperature control
- frantically searching and cutting some wire
- reinforce the springs with the wire using one hand, while pressing the caul to the form with the other hand, while monitoring the temperature and taking care not to burn my self
- realizing that the lower bout lifts...pressing down manually with a rag
- cranking up the heat and cook the whole thing a little at close to 300
- let it cool down and open a beer


I hope No 2 goes smoother...at least it didn't crack...
Christian

A set of 4 springs is $12 plus shipping.

_________________
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

If it's not cracked, and it fits in the mold you did a good job. I haven't bent Wenge so I can't comment on your temperatures. I'd recommend getting the correct springs from John. I wear welding gloves while bending just so I don't burn myself.

_________________
I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

Christian did you build from a set of plans? Just wondering. I'm planning on building one after I'm done my current project...Mike

Thanks for letting me know, John. I got some stronger springs today at a local hardware store. They're not exactly the size you recommended, but close. I already tried a 2nd Wenge side with them and following the procedure suggested by Todd Stock, it worked like a charm. The side was set in no time. I may order them as part of a larger order somewhen in the future nonetheless.

Woody - welding gloves are a good idea...probably better then the gardening gloves I was wearing yesterday and today.

Mike - I didn't follow any plan. I just studied some images I found on the web closely and started building. It's not really hard to do, but I took more time than I expected. During the process I really came to appreciate what a terrific deal John Hall is offering if you order the whole machine from him. If you add up the money for all the parts needed - blanket, controller, slats, press screw, springs, plywood,... - and then factor in time, you may realize that you're better of just ordering the whole thing

cheers, Christian