Inside mould

[rocket]

Has anyone seen or heard of an inside mould being used on a guitar build? similar to that of violin or double bass moulds.
Most violin makers use the inside mould but i have heard of some using the outside mould.
Pro's that i can think of is no need to for inside bracing/ spreaders and i think the sides might conform to the mould more easily, needing less clamping!
Con's you need to remove the work from the mould before completing the kerning/ lining to one side, so get one plate glued on then remove from mould and then complete linings and close the box.
My small shop is chockers with moulds/forms and bending forms but just considering trying the inside mould on the next build!

Cheers

Rod.

[sebastiaan56]

I’m on fiddle No 9 and have a bit of experience with inside moods now. The biggest issue is spring back. This is resolved by keeping the sides thin, 1.2mm for a fiddle. How that would work for a guitar is a good question.

FWIW French violins, the Mirecourt School, were built with outside molds.

[TomBeltran]

Ignacio Fleta, who started as a violin builder, used an inside mold to build guitars. There is a video available from Arts On Film, of him building a guitar and it shows his use of an inside mold.

[simonm]

The StewMac kits used to come with a cardboard inside mould. I did both a D and a Triple O more than a decade ago. Haven't checked if they have changed that. Worked quite well.

[rocket]

Thanks for your thoughts, i don;t intend to duplicate any of my existing moulds but if i decide to do a new model i might go with the inside mould!!

Cheers
Rod.

[johnparchem]

I have considered using an inside mold for ukuleles but I have never pulled the trigger on my thoughts. I put a pretty good radius on my guitar backs so I have appreciated the support of a mold and spreader as I sand in the radius. I am getting better at cutting my sides close to the finial radiused profile and bending the waist accurately to the cut profile such that I do nut sand very much and might not need the molds support.

I have also found that even with one plate glued on, the spring back in the sides opens the rim a bit. I build my flamencos top down on a work board and find that a mold helps keep the sides square while gluing on the back. In that case I am sure there are other ways to square up the sides with out a full mold.