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I just paid $60 for a sheet of baltic birch plywood. I am going to build a new outside mold and bending form. I just hate to have a lot of waste with the plywood at that cost. This is what I am thinking.

Cut one side of the outside mold and sand to the correct size. Now using that piece as the template mark out another side for the outside mold. This time scribe one line tight to the mold and then add a second line about 3/16" inside the mold line using a using washer. Cut on the band saw staying inside the pair of lines. With the two pieces I now a have an outside mold and a piece for a part of the bending form.

My question is would the bending form being 3/16" smaller than the outside mold be "too small"

I am pretty new at this so maybe there is already a more eloquent way to do this.

Any thoughts, thanks
Dave

I just did that very thing, except used about 1/8" inside the mold line to cut between and get a bending form .. works fine.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

The form needs to be smaller then the mold by the thickness of the wood plus whatever is under the wood(between the wood and the form. For example, I use slat, wood, slat, blanket for my stack. My sides are @.080" plus .020" for my slat, throw in a few thousandths for craft paper and foil, and I make my form .120" samller than my mold. I find if I make one master mold piece by cutting as close to the line as I can, then trueing it up on a sanding drum, I can use it as a template for the other parts. And I usually have enough on the cutout part to make my form from. I'll turn these two into masters, trace the mold master and cut inside but close to the line. Then screw the pieces together with the master and use a template bit on my router table to true them up.

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Rob

I like to glue a 1" strip of scrap wood along the bottom edge of my bending form pieces. Makes it easier to get a smooth bend at the ends of the sides if the form surface is longer than the side.

I use the inside waste to make the spreaders and there is hardly any waste.

Hi-lair-e-us Todd!

I do the same as Haans but use the inside for the bending form and sections of it for spreaders. I use a inlay collar kit to make the outside mold template and the bending form template from the guitar body mold. Using the inlay collar kit will give you an exact shaped outside mold to your body template. You can find that in the MIMF library. This YouTube is pretty much how I make the molds once the templates are made.
http://www.youtube.com/watch?v=TQ3ufWxQNjQ

Todd are you referring to my method? If so I cut the blanks close to the lines and then use the template to route the final shape. Then I remove the routing template from the section and screw that section to another blank and use the finished section as the routing template. Flip that over and add a new blank to the other side and route and flip and add and route. I don't have any problem with alining the pieces and setting some screws. On my mold for my Tricone( a squared corner form) I even drilled for 4-1" dowels that allowed me to remove sections of the mold when needed and to also locate templates on the mold for doing certain opperations as well.(See my tut in the MIMF library on building a metal body Tricone, I think it's probably one of the best tuts on the subject so far, and free) If I'm making the outside building mold I'll have a outside shape that's not squared corners. But if a square outside mold works for some one then leave it square.
Once someone has established their outside building mold template using inlay collar kit
http://www.woodcraft.com/Product/200139 ... c71e37ef06
then by adjusting either collars or bit sizes or both they can produce a bending form template of the proper offset or close enough.
The Inlay kit and a router template guides/collars and the use of them is very handy for making jigs and I use it a lot. I couldn't have made my tuner button jigs without it as well as my clam shell jigs for bridges to name a couple. Any time I need to make a template from an original piece it's the thing to use as long as you have the thickness to worK with. Something thinner and small then the McKensie duplicator would probably work.