thin top at soundpost


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I have always liked and used sheep skin patches (old drum heads, not the plastic type) slightly moistened so that it is very pliable.

There was an article in the Strad Magazine about 20 years ago about an English restorer (the name escapes this old memory) who used round punchings of sheep skin to underlay cracks instead of using traditional wood cleats. It was claimed that as the moistend sheep skin dried during the gluing process it would pull the two sides of the crack together as it shrunk and made a very strong underlayment and didn't add much mass to the joint.

I have used this method and find it quite effective. Anyone else use this method??

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hello

is it sacrilegious to use fiberglass? say .56 or .72 oz... with hide glue... i have seen it done that way :)

let me brace myself before anyone responds.

V_L_R

VLR - Ok, this is off topic, but I love that icon.

I once fiberglassed (using massive amounts of glass and resin) the arch back into a school bass that was so damaged that it had been take out of inventory and was awaiting the custodian hauling it to the trash. Ten years later, it is still going strong.

I think it all depends on the value of the instrument and the cost of the repair. There are violins where I wouldn't use anything but like wood (spruce on spruce or maple on maple) and there are violins that I would superglue or epoxy/fiberglass or even screw (with steel wood screws) or wedge (like the neck/fb) without a second thought.

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I have always liked and used sheep skin patches (old drum heads, not the plastic type) slightly moistened so that it is very pliable.

There was an article in the Strad Magazine about 20 years ago about an English restorer (the name escapes this old memory) who used round punchings of sheep skin to underlay cracks instead of using traditional wood cleats. It was claimed that as the moistend sheep skin dried during the gluing process it would pull the two sides of the crack together as it shrunk and made a very strong underlayment and didn't add much mass to the joint.

I have used this method and find it quite effective. Anyone else use this method??

Hi IBK,

Sheep skin or parchment can also cause cracks in instruments as it is usually still quite sensitive to changes in relative humidity. The cracks are often caused just at the edge of the sheep skin patches. It can be dangerous stuff.

If you don't have any evident deformation in the sound post area and there are plenty of annual rings you might want to hold off on doing anything. One reason for doing some reinforcement would be if the sound adjustments are difficult to impossible to do or the instruments falls out of adjustment quickly; indicating structural weakness.

Bruce

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Hi IBK,

Sheep skin or parchment can also cause cracks in instruments as it is usually still quite sensitive to changes in relative humidity. The cracks are often caused just at the edge of the sheep skin patches. It can be dangerous stuff.

Bruce

I was going to mention this, because someone else here (Darnton perhaps ?) has posted the same thing several times in the past, specifically about either parchment or some other organic patch material than wood - I don't remember the specific threads off hand, but I have never seen this happen personally.

I'm glad you thought to bring it up.

Plates are awfully thin and are apparently subject to this sort of contraction/splitting. The same force, I would think, that would cause the crack to "join tighter" as the glue dries.

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If other materials are liable to cause cracks, what is the reason people use linen reinforcement in patches on cellos (new), or to back up cracks?

Linen expands and contracts far less than parchment. Stradivari used linen strips on the inside of his cello ribs. The ribs are relatively thin and the linen probably helped stop any crack from running the length of the rib once started.

Bruce

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Old instrument.

Top previously thinned.

Soundpost area at 2.3mm.

Too thin? Patch?

Thanks!

++++++++++++++++

Too thin? If you have tapped it and played it and you feel the top is too thin, then

Forget it.

I don't know why people do thinning their violins. They think they are smarter.

Patch the soundpost area is the most difficult thing to do if you want good result.

Only if you can find your best luthier in town. I am not surprised if the guy or the gil is taking an vacation.

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I once fiberglassed (using massive amounts of glass and resin) the arch back into a school bass that was so damaged that it had been take out of inventory and was awaiting the custodian hauling it to the trash. Ten years later, it is still going strong.

If fiberglass is not recommended for your precious little violins, than why use it on a double bass?

I am also glad you included the obligatory Custodian reference, wile discussing the bass. Cracks me up every time!

A lot of Double Bass stories on Maestonet, always seem to include such phrases as "the trash" and "Janitors" or "hauling it away".

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If fiberglass is not recommended for your precious little violins, than why use it on a double bass?

I am also glad you included the obligatory Custodian reference, wile discussing the bass. Cracks me up every time!

A lot of Double Bass stories on Maestonet, always seem to include such phrases as "the trash" and "Janitors" or "hauling it away".

??

I realize that I have mentioned this particular repair here before.

Still, this is an "interesting" response to a meatball repair story... Obviously, you've never worked for a school system, on very cheap instruments, that have been beaten to death, and where anything goes in an attempt to save them from the trash. I assure you that this repair was exactly "as stated" and worse. None of it was fabricated in order to intentionally portray basses or bassists in a bad light - I promise ...

And in fact, over the years, I have used fiberglass on "my precious little violins" (and on cellos also) before...

In the realm of meatball repairs - there's probably nothing you can think of, that I haven't done.

And I think that most of them are probably still in the inventory and are still being used. Which is the entire point of such repairs.

In fact, what I have done to keep some of the bows (which, in a pinch, can double as either pointers or swords) in service makes the instrument end of the job look tame.

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Old instrument.

Top previously thinned.

Soundpost area at 2.3mm.

Too thin? Patch?

Thanks!

Crabtree says "Why not leave it as it is?"

I understand you want to avoid cracks.. but an acoustics question is interesting to me here. "What does it sound like?"

If you do reinforce the area, would you please comment on any changes of sound?

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Hi all.

Got called away yesterday, but thank you for all the responses.

The underside of the top is deformed at the s.p. location.

I'm going to opt for the maple veneer.

Scrape it down to 2mm, add the veneer, then take that down a little more.

Thanks for the responses.

I think Johnmasters deserves an answer to his question...... and I would add, WHY do you think you should take off even more wood to fix it? :)

Bruce

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Fair enough.

The top was off for a bass bar crack repair.

Someone had thinned the top(he signed the inside indicating as much).

The violin has not been set up and played due to the bar crack, so I can't tell you the difference before and after. My thinking went something like this, since the top is off, and the soundpost area is too thin, address the issue now, rather the after the top was back on and the sound was dissappointing or a crack developed.(I have no idea how long it's been since this violin was last played.) As the thinness was due to the actions of a previous person, I didn't have any qualms about preserving the "integrity" of the original instrument.

As to why I would remove more wood before adding a patch, there was a clear depression where the post was, and in the interest of eliminating that and making a smooth surface for the patch to lay on, I scraped the area till the depression was gone. About .1 or.2 mm

Yes?

No?

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As the thinness was due to the actions of a previous person, I didn't have any qualms about preserving the "integrity" of the original instrument.

As to why I would remove more wood before adding a patch, there was a clear depression where the post was, and in the interest of eliminating that and making a smooth surface for the patch to lay on, I scraped the area till the depression was gone. About .1 or.2 mm

Yes?

No?

Well, after all, the typical course for putting in a soundpost patch entails removing quite a bit of original wood, right?

So, with regard to your question, who knows?

If you know what you're doing there should not be a problem. But then again, "knowing" what you're doing, and what you're doing it to, is a relative thing, isn't it?

People who work on real world instruments, are often faced with making decisions about what to do with violins that require work, instruments which do not constitute valuable historical relics and which must be repaired within a realistic budget, based on time constraints, amount of work, and the worth and scarcity of the violin itself...

so, casting aside all romantic notions to the contrary, every violin repair cannot be treated as if the violin was a Strad. Those people who think it is otherwise, do not work as luthiers. I promise you, they do something else for a living. Something where they, also, must price their services within an honest, pragmatic, realistic framework, in order to satisfy their customers and pay the bills.

Whatever it takes to make the instrument playable, on such a violin is what you should do. What use to anyone is a violin that has been butchered by someone, and then has not been brought back to playing condition? Would it be better left "unaltered" - to sit and rot in an attic somewhere, because no one likes how it plays?

The idea that all violins are holy relics, never to be altered, is an idiotic romantic notion.

"Oh my God!, you did what? Now we'll never know what the intent of the original maker was!"

So what?

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Do you play to find sound? I would be interested in the sound before and after this repair. Not to check your work, but just for my general information about a two-thin soundpost area.

I have a 1/2-size school cello here. There was an old soundpost crack in the back which I decided to reinforce. I put a shoe across the crack. About 1.5" long (across the grain) and .5" thick and 5/8" high. The ends taper like a bassbar, rapidly. The center has a divit to take a soundpost with a pointed end.

I have found in the past that this works very well. You can even move the top of this new post around relative to the bridge foot.

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On the other hand, don't do this to a Gagliano, for example...

When I started back in Michigan we were working on school instruments too. The truck would pull up and unload the lot onto the concrete driveway including a barrel full of bows to rehair. We won't talk about what was done to repair these instruments so that the students could start fresh again in the fall.

I have had bad cases of damage in the soundpost area, caused by bad fitting posts and too many sound adjustments, where simply fitting a piece of spruce in to fill up the hole has been adequate and acoustically valid. The idea is not to remove spruce from the belly unless it is necessary. If you're doing a full blown soundpost patch then you do remove much more wood as ctviolin says. For myself, I like the idea of leaving things alone if I can and I don't think it is romantic to think this way. Even today I work on everything from Stradivari and Guarneri 'del Gesù' to the lowest form of student grade factory instruments with the intention of serving my customers without having to rake them over the coals. If, at the end of a repair, they go away happy it's the best publicity a violinmaker could ever have.

Bruce

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