Lowden bracing - hand planed radius vs machined

[Daniel P]

I've been reading all I can find about Lowden's approach to bracing, and recently watched this video:

https://www.youtube.com/watch?v=4kLr8-vZGhc

At about 9:56 he explains that at Lowden they hand plane the final radiused glue surface of each brace to create a more perfect glue surface. He readily admits that this is a small thing - but one of many many small things that may add up to have quite an impact on tone.

Are many of you taking time to prepare the sanded/radiused glue surface on your bracing?

Or could one make the argument that a very slightly ridged surface of a sanded brace actually creates a stronger glue joint?

[Dave Bagwill]

From what I've read, smooth surfaces actually bond better than rough ones. Sort of counter-intuitive.

As to planed braces vs. sawn or sanded, I will bow to Mr. Lowden's experience, but with skepticism; a well-radiused and well-glued brace, not planed, has made for some pretty great guitars.

$.02

[ken cierp]

I am sorry -- but blah blah blah --- the idea that Lowden workers make their glue joints better than other top tier makers is just marketing BS.

However, on the subject -- there is an accepted practice that does lead to poor brace to plate contact, this is the idea of sanding the contour of the brace gluing surface on a "radius dish." The results from this method can yield a gluing surface that is beveled on the outsides of the narrow width of the brace, in other words a rounded surface which will never make complete contact with the plate. It is far better to make the glue surface perfectly perpendicular to the height of the brace, this assures that the brace will lay flat on the plate in the narrow contact area (5/16" or 1/4").

[John Parchem]

plus 1 on Ken's advice\concern when using a radius dish for braces. I have learned the hard way. Conceptually I thought it was a perfect match as I glue the braces down in a dish, but I learned that I consistently either over rounded the brace leaving a gap along the glue joint or the brace glues on tilted. I now do what Ken advises.

[Daniel P]

I'm definitely aligned to Ken's recommendation to not use a radius sanding dish - the potential downfall is clear. Just waiting for the new KMG brace shaping jig :)

Whether or not hand planing the final brace surface is of specific benefit, I think we can all agree that close attention to detail is, if anything, a benefit, and leads to a higher level of finish on the final instrument. This awareness of the fit of each piece should only lead to better control of the tone - maybe not better tone immediately, but a better chance of controlling the variables.

[ken cierp]

+ 1 for close fitting parts. I do believe there are studies that indicate that roughing up a joint does not make it stronger. On the other hand a burnished surface does not allow the adhesive to do its thing at the molecular level, in other words the glue needs to get down into the pores of the wood.

[Dave Bagwill]

I've been unable to find any evidence that a well-done, sanded radiused brace is any likelier to fail at the glue joint than an equally well-done planed radius.
Agree/disagree? Has anyone here seen a brace glue joint fail due solely to it's having been sanded, rather than planed?