Side Bending - Luthier Tips du Jour Mailbag
In this episode, Robbie O’Brien offers several tips for successfully bending sides with a side bender.
Video Transcription
[on-screen text reads: Luthier Tips du Jour Mailbag]
Mailbag question: I'm having difficulty bending sides with my LMI side bender. Can you offer some suggetions?
Robert O'Brien: Today's Tips Du Jour Mailbag question comes to us from California.
"Dear Robert, I have the LMI side bender and I'm having difficulty bending my sides. Can you offer some suggestions? Thanks, Chris in California."
Guidelines for successful side bending
Chris bending sides can be a problem, especially if you have ornery set of sides that don't want to cooperate. Having the LMI side bender definitely increases your odds of having a successful bend. However, there are some guidelines that I can offer from personal experience that I think will help you.
Use practice sides
First of all, become acquainted with your side bender using practice sides. LMI sells practice sides fairly cheap, so use a set of those to get acquainted with the bender.
Dont' take too long
Also, don't take too long to bend the sides. When I bend sides in my shop, I'm finished with the entire operation in 10 minutes or less. Taking longer can dry out the sides and that risks scorching or even cracking.
Wrap sides in foil and be mindful of thermocouple placement
Something else that you can do is wrap your sides in foil or parchment paper. When placing thermocouples in the bending sandwich, make sure that they fit snugly. You don't want them to pull out easily. Placing them in the bending sandwich snug makes sure that you get an accurate reading on your temperature controller.
The mass of the press screw and the waist caul draw heat away from the stack, which can make you think your stack is cooler than it is on average. For this reason, you need to place the full blanket thermocouple a minimum of three inches away from the waist caul to minimize this effect.
Don't use sides that are too thick
One other thing that is very important when bending your sides is, how thick are they? If it's too thick, any side bending operation is going to give you some problem. So make sure that you have them at the recommended thickness for what you're trying to do. Usually, for me in my shop, that means somewhere around .080" to .090".
Set the right temperature
Something else that's very important is the temperature that you're using to bend your sides. When I did the original instructional video for LMI on how to use the new LMI side bender, I recommended 350 degrees Fahrenheit. LMI now recommends 320 degrees Fahrenheit as your target temperature. Any more than that, you could get a bit on the hot side depending on the species of wood, so keep it around 320 degrees Fahrenheit.
Half-turn every 30 seconds
Also, when cranking down the screw at the waist, when you're bending the waist, my original instruction said a quarter turn every 30 seconds. LMI now recommends a half turn every 30 seconds. That way you get through the bend a little bit quicker. Remember I said I'm done in 10 minutes or less. Get it done. That way things don't dry out. If things dry out, they could become too brittle and therefore you risk breaking the sides.
So Chris, I hope these suggestions that I'm offering to you from my own personal experience while bending sides help you become more successful when bending your sides. When it comes right down to it though, these are only guidelines. The LMI side bender is not some magical apparatus where you just push a button and your sides are magically bent. You as the operator need to have a feeling for what you're doing. That's why the practice sides are so important. Using practice sides in your bender will give you a sense of when the wood wants to bend. Listen to the wood. It will talk to you.
I hope this information helps and thanks for your question. Oh, and by the way, if smoke is coming out of your bender, it's probably too hot.
[on-screen text reads: More Luthier Tips and online courses available at www.obrienguitars.com. Private and small group guitar building and finishing instructions available.]
