Acoustic Guitar Construction

I've gleaned alot of info since I found this forum and thanks for it all. In all the pictures of the bending forms, I see spring steel for the slats. Is there a good source for it somewhere and will other metals ( like galvinized or aluminum flashing) work? Thanks- Steve

Hi Steve -- glad you are enjoying the forum!

I love questions like this, since it one of those guitar making myths mostly perpetrated by luthier suppliers and has become more inaccurate conventional wisdom. Your common sense has told you other metals will work and you are spot on correct! While with galvanize there is a chance of chemical reaction to the resin in the wood and/or water (I recommend distilled water no matter what slat material) it still can be used. Best to wrap the lighter color wood in parchment paper. The truth is all our (KMG) production benders not only use aluminum slats all our forms are covered with aluminum as well. I use material purchased from McMaster Carr and even Lowes and Home Depot. A thickness of about .023" works nicely. 2' x 3' aluminum sheets are very inexpensive about a tenth the cost of SS.

To understand how guitar making myths are born -- read this:
http://www.xenodochy.org/ex/calfpath.html

I remember reading somewhere years ago that Rosewood can stain the metal slats and they need to cleaned well after bending Rosewood and before bending a light colored wood like mahogany or Maple. One day it dawned on me to cover each side in aluminum foil before they go between the slats. No more stains or cleanup. I have never used the parchment paper but I would expect it does the same thing.

I too wrap my sides in aluminum foil....I bent a few sets and haven't tried any since I learned about using parchment paper, so I have yet to try it. As far as metal slats, I went to Hoe Depot and bought a 2'x3' sheet of flat ducting metal, and cut it on my table saw. WEAR PROTECTION, the metal slivers fly and stick into skin. Don't ask. Otherwise, works perfectly, and I just sanded the sharp edge smooth to deburr it. I think my total cost was $4, and I got two sets of slats out of it.

It does help to keep the slats in a dry, moderate temperature. I keep mine out in an uninsulated garage in the CHicago area. They collect dust, then moisture, and they do oxidize...doesn't impact the bending, but if you are finnicky about your tooling, find a good place to store it. That, or jus tmake more when you are sick of it...they are cheap enough.

well I've gotten the metal choice out of the way, and I had thought about using parchment paper for protection( see- all good minds think alike!) But I've been starring at my bending form now for several days and I just can't turn that switch on... oh the balls- where are they when you need them. This is my first attempt at a cutaway,and my throat's getting dry, palms sweaty... I think I've painted my picture for you. Anyway, it's only 100+ year old walnut. Somebody give me the push I need to pull the switch- oh the balls...

Steve

If you use parchment paper, which I have done, use two sheets of it. One on top, one on the bottom. If you flod the paper in half, it crinkles in the bends and can leave some marks on the wood that you need to sand out. Two pieces leaves no marks to sand out so you have a little less work down the road. This trick is even more important if you use aluminum foil to protect the wood. I bent a set of walnut, and to test this out, I folded the foil when I bent one side and used two pieces for the other. The side I bent with the unfolded aluminum foil had no crinkle marks to sand out while the folded foil side was full of them. They are not deep, but if I can avoid work, I like to do so.
Steve,
Bending the sides wont be hard. I had the same problem the first time I bent a set. I was worried I would ruin the sides so I got some practice sides from a guy on another forum for free. It was so easy, I kicked myself for not pulling the trigger sooner. I posted a video of the process:
http://www.youtube.com/watch?v=8yBs4ywxvqw

Easy as pie. In fact, I would have felt I had wasted my money if I had actually paid for the practice sides! I would suggest that if you are that worried, you practice on the piece you cut off from the side if you have pre-profiled them. If you have no practice wood, go to any lumber store and get something! Anything! Make a thin piece to practice with and then go for it.
What kind of bending machine heat source do you have? Blanket? Bulbs? Combo?

By the way, walnut is one of the easier woods to bend. It seems to like bending. You picked a good first wood!

thanks Tony, Actually this is my 5th guitar but first with this bender that I built. I have already bent the easy side and it went as well as it should. I am using two 150w bulbs and just switched to 200's for the other side. In the past I've used a pipe and bent this same walnut, I think you can look cross-eyed at and it would bend! It's just that extra bend in the side that keeps me looking for other things to do. Thanks for the paper /foil tip- thats why I keep looking here!
Steve