Finally starting to brace my first build

[nkwak]

I seem to be getting a little flak from some friends over my choice of not sanding a radius to the base of the finger braces. I intended to do the same with the tone bars too but now I'm thinking that I may radius them after all. What's your consensus?

[deadedith]

I started with cam clamps, then a go bar deck, then made my own version of a better gobar deck, then made a vacuum clamp with a strong bicycle pump - reworked - and it worked fine too; now I find I just really like clamps! Since I'm not in a huge hurry, I like the fact that there are no gobars to slip and ding; I get good positive safe clamping I can leave overnight and not worry about. That's just me.

I radius every dang thing before I glue it down. Again, just me. I don't argue about it.

[nkwak]

You even radius the bridge plate? To be honest I haven't heard much about the requirements of a bridge plate. All I've heard is that you either use maple of rosewood though every now and then somebody will use spruce for some reason. Other than that I haven't seen much regarding how thick it should be or what the grain orientation should be. The only thing I've seen definitively is that a poor choice in grain orientation can leave it susceptible to cracking under stress and to have the ball ends ship away at the plate.

As for using cam clamps, I like the idea as well but so far the method of using a radius dish and go-bar deck is easier for me to comprehend.

[tippie53]

never heard of radiusing the plate . Martin never did . The fact is once you cross grain glue 2 pieces of wood you have a dynamic platform that will want to move with RH Changes. The plate , top and bridge work as a unit . You can try it . I fit the bridge to the top and it becomes part of the brace system .

[kencierp]

Ditto John -- nice flat 1/4 sawn, perpendicular to the sound-board grain. The bridge, the sound-board and the bridge plate make a "most excellent" laminate (plywood). My method of assembly uses the bridge plate as the anchor point for the rest of the top bracing.

http://www.kennethmichaelguitars.com/topassembly.html

[deadedith]

Yeah, I suppose you could be right. Then again, say we've got a 40' radius - I radius the plate to match - it's not much of a radius - I also radius the bridge of course - so my sandwich fits together perfectly. No mashing. Takes me about 15 seconds to radius the plate.

I just don't think it is a detail to worry about that much. Then again, some days I feel like I don't know a thing...


Edit: I am going to go by the wisdom of those who know about these things and stop the practice of radiusing the bridge plate. Sometimes I can be stubborn enough that it is to my own detriment. Not prudent!! Thanks to Ken and John for stating their experience so clearly.

Onward and upward :-)

[deadedith]

I've taken a little time to think this over, and I see now what the principle is.

Main point: the bridge plate -to -top glue joint is paramount. There is no better way to get that perfect joint than by gluing a flat bridge plate to a flat top. Then the x-braces etc., glued in a dish or with the 3x5 card system. This will of course alter the flatness of the bridge plate to some extent, but the glue joint keeps its integrity. Then the bridge, shaped to conform perfectly to the top and plate makes that good laminate right there at the heart of things.

Pre-radiusing the bridge plate is putting the cart before the horse.

I know there are other approaches; but this is my method (actually Ken Cierp's) and it makes a lot of sense to me.

[nkwak]

I was told to just use a rift sawn piece of wood for the bride plate so that it bends to conform. Like you said deadedith, the glue joint should help with structural integrity.

BTW how thick should the bridge plate be? A friend told me to go for about .1".

[deadedith]

You will surely get a few answers - Somogyi's book stated .090, mine are around.095-.1

[nkwak]

I put the X in tonight using the radius dish and some cauls to ensure that the go-bars don't slip. The lower face bars go on next time.



I decided to put off the lower face bars and just glue in the X brace. This time I used the radius dish and I also took precautions to make sure that no go-bars slipped off!



BTW, I also tapered the ends of the side finger braces with a chisel. This isn't their final shape yet though.