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Hi

Do you know of any resources on the web that explains the geometry of cutting the sides before bending. I am assuming that the end of teh sides near the heel and tail block have to level out so the are parallel at some point ?

John

If you work with a dish, or a cylindrical form, it is relatively easy to mark your side profile with the mold. I think there are a couple of tutorials on how to do this on the OLF. Once you have your line it's a matter of making a jig that will do both sides at once with a pattern bit for example.
Personally, I keep one "side" of the side set flat, usually the top, for reference, and don't even bother to profile the sides before bending. I cut my sides with the desired measurements at the butt and head, it's very fast to profile them with a block plane and the form.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

I do it in CAD, but there's a fine real-world analogue:

Buy a piece of cardstock long enough to get halfway around the guitar, stick it to the sides with -gentle- double stick tape leaving it proud on top and back, and trace the profile of the top and back onto the inside of it.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

When working with a new design, I do it the way Laurent describes. Once you've built one, (And you like it) make a side template with card paper. I still like to leave 1/8" extra on the back edge of the sides & leave the top edges straight.
Just in case...

I've seen that very question asked enough times that I'll bet if you came up with one you could sell it commercially. I'd be a customer.

Here's a tutorial I did on making side templates some years ago, it is very simple and foolproof.

http://www.luthiersforum.com/forum/viewtopic.php?f=10102&t=8117%22

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

I do it like Bob does - I profile them before bending. I have a router template that I made that also includes a small tab shape to mark the center of the waist on the top of the side. This is one of those things that is actually easier to do on the router table than it is on the CNC. I use this to keep the side in the right position relative to the bending form.

Trev

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http://www.PeakeGuitars.com

Colin's method is great and I think John Hall offers side templates for just about anything. When I was just starting out I ordered some profiled but unbent sides for an OM and Dred from Martin and made templates from them. Those are the ones I still use for those sizes. I just leave the top flat and sand the profile into it with the dish after the rim is glued up. I always profile before bending and leave them a little long on each end.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Hi

Now I can see my pre bent and profiled sides in the mold it dawned on me that all I have to do is trace around the profile on some card making it repeatable. I will be doing this for the OM I am working on. I will also try tracing directly off the radious dish.

Thanks

John

My .02 cents on this. If you are profiling a cutaway body, you have to make the side with the cutaway a bit wider in that area to compensate for the fact that the side is higher at the cutaway, due to the radius of the back. FYI ...