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My method for gluing the top and back of my classical guitars

I use an outside mold and the labelled back is shown propped up in the sides and ready for the back brace pillars (offcuts of the kerfed lining).


Here's the back ready to be glued to the garland of sides using Titebond glue and my go-bar deck. I pad on the glue with a sponge.


Back being clamped using gobars. Pressure is applied right over the linings. Putting the back on first allows for good glue cleanup.


The top is also glued with Titebond. Here. the mold is placed on little legs to allow access for the clamps. They are just the spring component of dryer hose clamps and exert just the right amount of pressure, A strip of Masonite, rough side up, cushions the springs and keeps them from skidding onto the top.


When the glue is set, the springs come off in handfuls. The fun part.


And, the finished box. Now on to the much anticipated cutting of the binding rebates. I need a drink.


Photos courtesy of John Jones (client for this guitar)
Makeup courtesy of Dotty's Pet Grooming.

Views: 921

Comment by Cliff Morris on June 18, 2009 at 8:59pm
Very nice Bob. Sure is helpful to see how everyone does this. I notice you use a caul over the neck block on the top but not on the back, Any reason for the difference?
Comment by Bob Webster on June 18, 2009 at 9:48pm
There is so much pressure on the neck end of the back just to bend it down to the neck joint that there's plenty of squeeze on the glue on the Spanish foot. The foot is actually in the way of the back and the back would really rather go flat past the brace. It can't because the foot sticks up and puts pressure on the back. Does that make sense?
Comment by Donald A. Fortune on June 19, 2009 at 8:45am
WOW Bob -- I am in awwww you have your stuff together.. I like the go bar system for holding the back while the glue is setting up.. Where did you ever get thoes spring clamps to hold the top on while the glue sets up??
Nice work too :-)
best to you,
Donald
Comment by Bob Webster on June 19, 2009 at 9:04am
Donald, I ended up finding them at Rockler Woodworking. Regular hardware stores in Washington don't carry them any more because current code disallows their use. Go figure. As for the gobar gluing of the back, I may start using the Masonite rims on it too just to ensure that I'm getting the pressure from the gobar distributed a little better. Haven't seen any problems with the current method, but better safe than sorry.
Comment by Cliff Morris on June 19, 2009 at 11:31am
Yes I think it's clear. With just the back going on there is enough give in the ribs that the foot stays firm against the back. Both pieces give a bit to find their correct fit. Next question: You have the spanish heel inside but is the neck of your design tennoned or dovetailed to the heel block? The traditional way is for the neck and heel to all be one piece correct?
Comment by Bob Webster on June 19, 2009 at 12:42pm
It's tenoned. I do that so that I can finish the body and the neck+fingerboard separately. Actually, the neck heel has a mortice also, so I guess the correct term is a spline joint. I havve some pics I could throw into a separate blog on the neck joint. Want to see them?

As for give during the gluing, I really don't know what it is that's doing the giving. The sides are braced with spreaders against the mould and the neck block is fixed upright via a bolt through it to the exterior of the mould. That leaves the back itself. How it manages to accomodate the change from a tubular shape with a radius of 25' to a dome with the same radius, without anything else also deforming is one of nature's mysteries (at least to my senior grew up in the '60s brain). It has to create a significant amount of tension in the final structure.
Comment by Luis G. Bianchini on August 29, 2009 at 11:02pm
Dear mr Webster... have you used " Steam sourse" as an ironing steam system for bending sides?
thanks for any help.
Luis

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