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Wesley S. Boyd

Separating the Violin Top (or Back) From Ribs, Lining and Block.

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How do you approach dissecting the top (or back) from the body of a violin? Is it separated with a knife then leveraged off? I read an article about a person re-graduating the top when fixing a crack for sound improvement.

I look at my violins and can't imagine how you guys approach this feat.

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I use a piece of thin 3/4 inch high-carbon banding strap that I've cut to a point ala Exacto knife angle and sharpened one side of the angle to a fine point. Carefully insert this into the joint area where the chin rest will be and open the joint just enough to then insert a thin Sheffield kitchen knife blade into that opening.

The joint will pop with agonizing sounds as you work the blade toward the middle and upper bouts. At the end blocks you need to use endless patience to work the knife point ( also an exagerated sharp point) into the glue joints and pop them loose. On many violins the corner blocks will also be an area for more patience. Using a Q-tip you can introduce alchohol down the blade to the block glue to hasten the release of the glue but keep a tissue handy and don't get any on the exterior finish.

Always use extreme care to aim the banding strap blade straight 90 degrees to the ribs to avoid sliding the point into top plate wood. Good luck.

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There is often a portion of the glue joint that is already weak or even loose. Look for it. Pay attention to grain direction, especially on the top. Minimize splinters. If your knife separates one from the top, it will ride up the resulting wedge shape of the splinter. Stop immediately and begin working in the other direction.

Use a blade that applies wedging pressure to the glue joint. A sharp edge can cut wood and begin the dreaded splinter removal process.

Work slowly, and with patience. You can hear and feel the difference between a separating glue joint and separating wood fibers. Minimize using a sharp point or edge to begin separations, you risk catching a splinter each time you do so.

Good luck,

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Most tops will have some degree of runout somewhere - you won't ever get a top with absolutely no runout along the edges. It is important to separate the plate in the direction of the runout (towards the downward-slanting grain). If you do it the other way the chances of the plate splitting are very good. The runout will determine where you start the operation, and this might not necessarily be at the chinrest position. Also, take some time to check the direction of the runout all around the edge. Sometimes there are twists in the grain and you hit a spot where the runout is in the opposite direction from where you started to lift the top. You don't want to be alerted of this by an unexpected splitting of the edge.

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quote:


Originally posted by:
W.S.Cool

How do you approach dissecting the top (or back) from the body of a violin? Is it separated with a knife then leveraged off? I read an article about a person re-graduating the top when fixing a crack for sound improvement.

I look at my violins and can't imagine how you guys approach this feat.

I will repeat the method described by our absent Mr. Darnton. After finding a slight opening, a very small amount of alcohol is introduced to help cleave the bond. Work around slowly with thin pallet knives for example. I myself use a 50-50 mix of alcohol and dilute ammonia which also works well. Keep it off the varnish, needless to say.

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I regularly use a very thin knife heated on a clothes iron.

I know --it isn't supposed to help-- but it does. I understand all the reasons it isn't supposed to help; I'm not gonna argue the point. All I know is that where I live (is humidity involved?) on the violins I work on, it helps a lot.

The fellow who originally shared that with me lived in the UK, which I believe has roughly the same micro-climate characteristics as western Oregon, so possibly that is part of why it works. Maybe in a drier place it would not work. Except that I did it in Tucson too, and it worked fine. So maybe there's something wrong with my glue...I dunno.

Try it, if you want... I have also found that if I heat a FB with that iron, and then the knife in removing it, it goes very smoothly.

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Tops are also generally easier to get off the rib garland because initially a more dilute glue is used, because the maker expects the top will have to come off in the far future (not that he wants it too).

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I wouldn't try this first on a good instrument. It would also be good to watch someone do it before trying it yourself. Make a note that some instruments have small wooden pins through the front into the end blocks that have to be dealt with. Also, be very careful around the corner blocks so that you don't break the corners off the front.

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quote:


Originally posted by:
fidleir

Does anyone use steam or heated knive?


I use a small syringe to apply alcohol (run a small bit of it into the seam on the blade) in the tough spots.

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All, Thanks for the responses.

The real caveat to my story... When I make my violin, I'm not sure I desire to graduate the top of violin "tone zones" real thin (meaning down to 2.5 mm in certain places).

I would like to graduate my spruce top to 4 mm in zones, secure the top, and play the violin (pre-finish). If it does not sound right, I want to be able to pop the top and re-graduate a little thinner if required. My wood is Engelmann Spruce and it is very light.

Sincerely, The Carving Coward. -Wes

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Wes, as I understand it (and I may not), a light, "fluffy" wood like Engelmann should probably end up a bit thicker than a heavier, denser, harder wood like Sitka. More experienced guys: is that right? I've read that there is a target weight for a back and a belly. Search here on MN, you'll see Mr. D having posted on the subject. If that's true, then that would indicate a lighter wood would end up thicker, to some degree.

Caveat to your caveat: I'm pretty sure planning to pop the top just to adjust it is not the greatest idea, especially for a beginner (more experienced guys will chime in here). Note that I'm just like you - working on #1. Anyway, I think it'd be a better idea to put aside any preconceived notions about thickness until you get there, and make the plan to get the plate as "right" as possible before gluing it on, whatever "right" turns out to mean. Lots of help available here. Can I assume you have an accurate dial caliper or equivalent? That would make all the difference, but you can also tell quite a bit by holding the plate up to a light and seeing where the thicker parts are...

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Tim,

An electronic bench caliper (+/- .0005 mm) is in the mail as I type (along with an array of numerous new tools). I have 5 violins and I don't think I embrace any of them. I want to make my own.

I'll do some searching on MN for Engelmann as you suggest. Thanks for the input.

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A really, really thin knife with the edge dulled so it won't cut

into the wood is worth its weight in gold, I found mine at an

antique store, I'd guesstimate the blade is about .5mm at its

thickest. I don't find I need any alcohol or heating the knife if

the knife is thin enough, sincerely Lyndon

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Yesterday I used a set of $2.00 palette knives from Chinatown to remove a bass top, first time I've done this. I had them all warmed on a clothes iron like COB3 does, and used one after the other. They are thin and blunt and easy to use. I used thin wooden wedges and paddlepop sticks to hold the wood open as I worked around. I am convinced the heat was useful, especially at the end blocks which were very tightly glued.

I am leaving my bass top thicker than usual because I am using lighter wood. I may have to remove some more wood if the instrument does not speak to me. Use very thin glue on the belly especially if you want to remove it later.

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