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Building a Classical Guitar #5: The top

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Blog entry by kem posted 11-12-2008 07:33 PM 9984 reads 1 time favorited 8 comments Add to Favorites Watch
« Part 4: The sides Part 5 of Building a Classical Guitar series Part 6: The back and back braces »

The kit for this classical guitar came with a bookmatched pair of Engelmann spruce boards for the top. My pair has some beautiful silk in it that I hope will come out in the finish. After jointing the inner edges of the two boards and tapering the opposite edges. We used a wedge jig to glue up the top. The wedge applies the clamping pressure to the joint in the middle of the top.

I then used hand planes to surface the outside of the top.

The next step is installing the rosette to this outside surface. We used a Dremel and a circle cutting jig to make the channel for the rosette.

To glue the rosette into the channel, we used the go-bar clamping system. I didn’t get a picture of this but you’ll see plenty of examples of using this clamping system as you read on. I flushed up the rosette to the top using a block plane and cabinet scraper. You can see some of that sweet silk in this photo!

Using a drum sander, the top was thicknessed to 2.6 mm.

For the bracing pattern, I used the one included with the kit which is the pattern in Segovia’s Hauser guitar.

The first piece to be glued in is the bridge plate. I made a bit of a mistake here with the bridge plate. You can see it doesn’t really match the pattern above. That’s because I made it before consulting the pattern! Oops.

Here are all of the spruce braces after cutting them to size and roughly laying them out.

You can see some of the braces need to be notched to fit over the bridge plate. Robbie showed us a clever way of doing this using a bandsaw. Check out his youtube video.

Here is a picture of the first set of braces to get glued in with the go-bar clamping system. This system uses flexible rods bent between two decks to apply pressure.

The reason for gluing the braces in in steps is to give you room to shape the braces using small planes and chisels. Here is how I shaped the fan braces.

Here’s the final glue up of the remaining braces.

And here is the inside of the top after everything has been shaped. At this point, you can tap the top and hear a satisfying resonance that sounds like a tuned tom-tom.

-- Kevin



8 comments so far

View YorkshireStewart's profile

YorkshireStewart

1106 posts in 2539 days


#1 posted 11-12-2008 09:38 PM

Thanks for this series Kem. What a simple yet effective way to cut those notches. I’ll be using that for all sorts of applications.

-- Res severa verum gaudium - True pleasure is a serious business. http://www.folksy.com/shops/TreeGems

View Grant Davis's profile

Grant Davis

615 posts in 2546 days


#2 posted 11-12-2008 10:07 PM

Nice blog, what are your rod clamps that you are using on the brace glue up made out of….fiberglass?

-- Grant...."GO BUCKEYES"

View Chris 's profile

Chris

1867 posts in 2629 days


#3 posted 11-13-2008 12:29 AM

Thanks for the the blog… I’ve not heard of the go-bar clamping system before.

I just found this with a quick Google search:
Go-Bar Clamping System

-- "Everything that is great and inspiring is created by the individual who labors in freedom" -- Albert Einstein

View GaryK's profile

GaryK

10262 posts in 2626 days


#4 posted 11-13-2008 12:34 AM

Great blog Kem!

Chris – You can find them and a lot more tips here:
http://lumberjocks.com/jocks/GaryK/blog/2554

-- Gary - Never pass up the opportunity to make a mistake look like you planned it that way - Tyler, TX

View Todd A. Clippinger's profile

Todd A. Clippinger

8775 posts in 2737 days


#5 posted 11-13-2008 02:43 AM

Thanks for sharing, this is a pretty interesting process to me. Your work is definitely tight.

-- Todd A. Clippinger, Montana, http://americancraftsmanworkshop.com

View Doug S.'s profile

Doug S.

295 posts in 2345 days


#6 posted 11-13-2008 06:41 PM

Thanks for posting this. One question on the Go-bar clamping. It looks like most of the rods are bent in the same direction on each brace. What stops the brace from being torqued over sideways? I would have thought you might need equal number of rods bent in opposite directions to counteract the sideways force??? I guess not because it obviously seems to be working but just seems counter-intuitive.

-- Use the fence Luke

View kem's profile

kem

56 posts in 2356 days


#7 posted 11-13-2008 07:35 PM

The go-bars are flexible fiberglass rods. I like the skinny cylindrical ones in the second to last picture better than the rectangular rods.

Good question, Doug. You do have to be careful with the go-bars. Always wear safety glasses cuz they can shoot out in exactly the situation you suggest (a brace falling over sideways). This isn’t much of an issue with the short braces, but the tall skinny braces are inherently more unstable.

If there were no glue and no friction, you would be correct in trying to balance the forces laterally. In gluing these in, you need to let the glue set a little bit before putting in the go-bars. Otherwise, they can easily skate around. I guess the tacky glue and the tremendous amount of downward force counteract the relatively small lateral forces being applied.

-- Kevin

View robbie's profile

robbie

9 posts in 2152 days


#8 posted 11-14-2008 05:41 PM

Keep up the good work Kevin! I can hardly wait to hear your guitar.

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