Official Luthiers Forum!

Those who make their own forms, what do you use to hold the two "outlines" together.
I see for example that Bruescreek Guitars use metal tubing, and I believe I have heard of people using aluminum "strip", (maybe about 3/4" x 1/8" on "edge")
Just wondered what you guys use, and do you secure them in some way, e.g. are epoxy/superglue fit for temperatures involved, or do you use screws/pins, etc?

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

I have a Blues creek bender, it came with one bending pattern D size, with the 1/2 conduit to hold it together, I misplaced the conduit and substituted 1/2" poplar dowels. I've built O, OO, OOO/OM & Gibson L-OO/Nick Lucas bending patterns using the dowels works great.

On my first one I used 3/4" hardware store dowels, made of some kind of some type of inexpensive Asian wood. They are glued with Titebond but I imagine a friction fit would work. For my second form, I didn't use spacers--I followed Todd Stock's tutorial on this forum, which suggests using thee layers of 3/4" plywood. Having tried it, I am partial to that method and would recommend you consider it if you haven't yet. Of course, both types seem to work pretty well.

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Tim Allen
"Never hurry, never rest."

I use 6 pieces of 3/4 inch plywood and make a solid block form. Sometimes I cover it with HPL if I am also going to use it for molded sides. I use kerf core as a "clamping blanket" over the heat blanket or as an outside form for molded sides. I use titebond to glue up the block form. The forms are a bit heavy but "solid" and easy to make.

I too use a solid form. I use Baltic ply on the outside and MDF pieces for the center. I make it with a cavity in the center so the center pieces are lighter. Then I cover it with a stainless steel slat

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Joe Beaver
Maker of Sawdust

Solid form........!
Tom

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A person who has never made a mistake has never made anything!!!

I initially started with the two outer forms with steel rods between per the plans I used. However, I have since switched to 3 forms with plywood spacers connecting the three pieces. I think you get better support across the width of the sides as you bend. A solid form would be even better. This assumes you're bending with a blanket and not using light bulbs.

For this one I want to try both heating blanket and light bulbs.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Double width Fox bender, heating with globes, 12 off, 1/2" steel bars, 300mm long, push fit. One set of bars for many different forms so that the forms store flat. It takes about a minute to assemble a form by threading the bars in.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

I have always used two forms with 1/2" wood dowels instead of steel but on my last form I did it with 3 forms and only a few dowels to hold it together. This will not work with bulbs but I think the advent of the heating blanket being available make the bulbs obsolete. I always thought that bulbs were a dangerous and unreliable way to create heat.

Here is a shot of my Bouzouki form and outside mold.

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Fred Tellier
http://www.fetellierguitars.com
Facebook page http://www.facebook.com/pages/FE-Tellier-Guitars/163451547003866

This. No need to glue in the bars unless you have way too much storage space.

I do pretty much the same, 1/2" plywood with 20 1/2" steel bars, use the same 20 bars for jumbo, dred, L-00, and parlor. I still use light bulbs for heat. I'd go to a solid form if I used a blanket.

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A man hears what he wants to hear, and disreguards the rest. Paul Simon

One thing I forgot to mention, and another reason I use a solid form, is that I make the block form and the outside mold at the same time. I cut just inside the outline on 6 pieces of 3/4 inch plywood, and then between routing and sanding to true up the patterns I have an outside mold and a block form of about the right dimensions.

I use a light bulb base with two 150 watt bulbs and build all my molds to fit on or around that base.
I build the side forms from 3/4" particle board lined with aluminum foil (spray adhesive). The forms are separated using 3/4"square wood spacers drilled finishing nails (aluminum foil preferred) two inches between them. Flashing aluminum covers the mold.

It has worked for me so far.

Bob