Official Luthiers Forum!

I wound up thinning my new Black Walnut sides just below 2mm. Do you think they are sill usable?


Scott

If you're careful and they don't ripple much then yes you'll be ok.

_________________
John Mayes
http://www.mayesluthier.com

I'd use them without even doubting. I often go as thin as 2mm or under for sides.

_________________
Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

This is only the third type of wood I've bent so far. The Black Walnut bends like a dream, no ripples at all. I bent the sides at just under 2mm.
I'm sure they would have bent at 2.5 mm with no problem. I never went over 280 degrees and the whole process took around 20 minutes

Thanks again

Not too thin as long as you won't need to sand much more after bending. Are they smooth now, and will you ben bending with a Fox bender or by hand? Either way, you'll just need to be very careful and precise. Not much meat there for sanding after the fact.

Thanks Corky. I did bend on a Fox type bender and like you said after sanding I'm well under 2mm, around 1.5mm at this point.
Now I'm even more nervous about using them. Do you think using side bracing to compensate makes any sense?

Scott

One option is to bend another set and laminate them. You are at about 0.060 and that's too thin for me even with a bunch of side braces.

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

A simlar solution, although smaller, would be to laminate some veneer under (meaning on the 'inside' part of the side) the parts that are a little thin. Work the sides as normal, with linings and side braces if you use them, and then finish with the laminations.

_________________
Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

I'd also go with a laminate.
(edit: math error!)
I don't have much experience but on my current build I bent my EIR sides at 0.080 and after rectification and inside finish sanding, i'm about 0.070. I have 5 side braces on each side and find them too flexible. I would prefer a more rigid structure but I guess it's a matter of taste.

_________________
Francis Richer, Montréal
Les Guitares F&M Guitars

2mm is .079". That is normal side thickness in my shop.

_________________
Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

I also mistakenly thinned some walnut sides to less than 2 mm. I had already invested time in the matching back, so I decided to try to salvage them. Laminating veneer to already-bent sides seemed fraught with ways to go wrong, so I tested laminating veneer to the side before bending. I had two scrap sides to use, and walnut veneer that would add enough thickness. I tried fish glue and polyurethane glue, clamping the side between boards to veneer. Once dry, I used a Fox bender with a heating blanket, following the procedure demonstrated in Todd Stock's tutorial. While the fish glue test side de-laminated a little bit, the test side with PU glue bent just fine, so I went with that. The completed sides are assembled and it looks like the fix will work well.

If anyone wants to try this, you should know that Gorilla brand PU glue is supposed to be inferior, and before using you should test any PU glue to make sure it's fresh enough to work.

This whole process was time-consuming, but on the other hand I saved time by hurrying through the original thinning process.

_________________
Tim Allen
"Never hurry, never rest."

2mm is the thickness I use as well. If a wood is difficult to bend I have taken them as thin as 1.6mm and been fine. I have seen historic guitars (spanish classical) that were below 1.5mm.

I have bent sets that had thin spots (I use alot of BRW that tends to be cut tight) and often will glue a layer of veneer inside prior to bending and once dry will sand or scrape to the desired thickness and then bend. Unless if the side feels weak after bending or you are afraid it will split at some point in the future, you can laminate a layer of veneer inside a bent side if you support it well. I use a side form lined with bending ply that is cut to the outside dimensions and shape of a side which I then use as a support for the bent side. When I have glued in a layer of veneer, I then use plastic bags filled with fine sand to apply pressure to the veneer since the sand bag conforms to the surface of the inside of the side.

To thin... Or not to thin.

Walnut bends like butter, just below 2mm as in about .075"? Go for it, my sides rarely exceed .070" in thickness and for harder woods are just about .060".

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