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I was approached yesterday about possibly replacing a top on a classical guitar that has seen more than it's share of wear and tear.
The present top has several long cracks, both new and old (with questionable repairs). The guitar doesn't sound all that great and I wonder how many braces are intact.

The owner is in the market for a new guitar, and I ventured that it would be easier for me to build him one than repair his at that level, but I think he is going to go for a fairly high end guitar, and is mainly offering me the existing one for the experience. I'm game and it's the sort of repair I should learn how to do. I am envisioning routing the top off inside of the top bindings and putting together a drop in replacement, but I'm wondering whether you try to save the top purflings (and this guitar has a set of very fine purflings, probably 8 in all with very thin material), and how do you manage controlling the cut so you cut right to the purfling lines and not beyond.

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Jim Kirby
kirby@udel.edu

Jim,

I came across this method a while back. I've never tried it, but it looks like it should work for you.



www.grevenguitars.com/retopping-demo.html

Jim, I've done this before by simply routing the top off like I was cutting very wide purfling channels, then re-binding. It goes pretty well.
There have been a couple of articles in past GAL issues if you have those. I haven't read them in long time but I managed to remembered they were there.
Jeff Elliott has one in #34, I believe this is similar to way I've do it, but I'm not certain. And Harry Fleishman has an article in #100. I believe he preserves the binding and purfling in his technique. These are probably worth reading if you have them.

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Jim Watts
http://jameswattsguitars.com

Thanks JIm and Mark, I'll have a look. As with any older guitar, I'm worried about being able to match new top bindings to the back bindings if I rout off everything. If the bindings look easy enough to match, I may just go the simple route, and can then just purfle the top any way i want.

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Jim Kirby
kirby@udel.edu

I've used this method and it works great.Don't even have to rebind it just add purfling.

OP what is the make of the classical guitar?

I've done a couple. In avoiding having to cut new pockets for the inlet braces, I fitted all the braces into the old pockets, then lightly glued the top onto the braces, took the top off with the braces, used locating blocks on the go bar deck against the new braces, popped them off, and did the real brace gluing using the blocks to duplicate the brace locations.

There's the fretboard issue too, whether to remove it. Some folks keep it on and work under the FB extension.

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com

Here are some videos about replacing the top and saving the bindings and purflings.

http://www.youtube.com/watch?v=MQihQUn6YOU

Finishing is a lot simpler when you save the bindings, and matching finish is the hard part of any repair in my book. I'd remove the fingerboard. Remember to shape the new top before you rout the old one off: the sides get pretty flexible once the top's off, and it gets hard to maintain alignment. With wide purfling you may want to add a bit of width to the liners; easily enough done with a bent piece.

It's a luthier guitar but no one of any significant reputation - I've forgotten it since Sunday. The guitar is dated 1982. Owner is English originally so I'm guessing the guitar is too. I'm not worried about destroying the value of an expensive instrument. I do want to check it out first before making any decisions about taking it apart. it turns out the back has cracks in it too.

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Jim Kirby
kirby@udel.edu

Anyway, keep in mind that the tutorial shown by Greven is for a steel string guitar. Beware, the biggest challenge I found in replacing the top, is getting the right neck angle. So, if you are going to retop a classical guitar with no removable neck, you might have a problem.

Good point. That could lead to some very careful measuring being needed. I admit that I don't always get it right during initial assembly of my own guitars yet - I almost always have to do at least a little fretboard tapering after assembly.

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Jim Kirby
kirby@udel.edu

The Fritz Damler videos are for retopping a classical, and he talks about maintaining the neck angle as well as saving the purflings. As a learning experience I think it might be nice to see how much of the original trim (and rosette) can be saved, so if a more valuable instrument needs a similar treatment one might have the experience to do it. It may also show the pitfalls of the method. If it becomes a total failure then retopping and rebinding in the conventional way is still an option.

If the rosette has some reasonable thickness, it can be saved. Glue something like thin plywood (get it at a model airplane shop) or card stock to the rosette. Cut around it carefully, taking care to not hit the rosette itself. Plane the top wood off the back side until you just get to the rosette, Trim around it inside and out carefully. Inlay the sandwich as you would any rosette, only going just deep enough with the rout to house the wood part, with the sheet stock standing above the surface. When it's all dry, carefully plane/scrape/sand back to the rosette and level the top up. I used this technique a year or so ago when replacing a top on a steel string that had a fancy shell rosette, and it worked well.

Again, if you cut the new top to shape before removing the old one, it goes a long way toward maintaining neck alignment. Clamp the new top to the top of the guitar with spool clamps, and scribe around the edge carefully. I like to plane back to the scribe line, and check it against the original at that point. Then I use a marking gauge to scribe a new line in from the edge by the width of the binding top, and plane back to that. Check it one more time on the guitar before you rout off the old top. Once the old top is gone, and the ledge cleaned up, the new one should just drop in and will push everything back to where it should be. Then you can brace it up. Yes, it's fussy work...