Thickness of lower wings

[Roland]

Due to some over-enthusiastic scraping, the lower wings of the top I am currently working on have become a too thin -- around 1.8 to 2 mm in the region of the fluting. Comparing the graduations of several Strad posters, I realised that this area is always reasonably thicknessed (around 2.6 to 3.5 mm). It is probably just a result of their technique, yet I seem to recall that this area is also of some acoustic importance (maybe our acoustis experts can shed on this -- Don?).

I might add that the wood is quite dense (around 430 kg/m³).

Currently, I can think of three options:

- leave it like that

- add a cleat to the wing

- glue a spruce "veneer" (maybe a thick shaving) to the wing (on the inside, of course )

 

Any advice would be welcome!

 

 

best,

Roland

[Don Noon]

Although the lower wings do flap appreciably at certain frequencies, if you look at the area involved and the frequency (plus the fact that they aren't tightly coupled to the bridge), my conclusion is that they can't do much acoustically.  The response plots appear to agree.  Structurally they do absolutely nothing.  I tried cutting them off, and the only change I could find was a shift in the air mode, due to the increased F-hole area.

 

I'd go for the first option - leave it like that.

[Roland]

Ha!

That would definitely be my favourite option!

 

Thanks Don!

[Oded Kishony]

Although the lower wings do flap appreciably at certain frequencies, if you look at the area involved and the frequency (plus the fact that they aren't tightly coupled to the bridge), my conclusion is that they can't do much acoustically.  The response plots appear to agree.  Structurally they do absolutely nothing.  I tried cutting them off, and the only change I could find was a shift in the air mode, due to the increased F-hole area.

 

I'd go for the first option - leave it like that.

 

I seem to recall a thread where you concluded that the wings absorb energy, but since they do not radiate well the result is that the wings dampen certain frequencies. Have you changed your mind about this?

 

I think wings can cause noticeable change in the sound. Now that the wings are thin I would ignore it until I hear the violin and find out if there is any particular acoustic problem.

 

Oded

[martin swan]

Probably Stradivari left wings a bit thick so they didn't break off or lose corners too easily ...!

It's a very vulnerable bit of a violin.

[Bill Yacey]

I think I would be inclined to put a small cross-grain cleat. Eventually it will be subject to cracking, especially in an overly- thin state.

[Don Noon]

I seem to recall a thread where you concluded that the wings absorb energy, but since they do not radiate well the result is that the wings dampen certain frequencies. Have you changed your mind about this?

 

That was the inner wings.  The inner trebel wing is definitely an important player, inner bass not so much, lower wings not.  At least, that's my present understanding.

 

 

I suppose some reinforcement might be reasonable, depending where the thinness is.  If the area above the eye is thin, I'd reinforce that, to prevent wing cracks.  Otherwise, I'd leave it as is, and fix things later if you find it is needed.

[Muswell]

I did the same.  I decided to leave it and repair if necessary, The violin sounds good,but then again maybe it would have been better with thicker wings.  Such is life.

[Don Noon]

The violin sounds good,but then again maybe it would have been better with thicker wings.  Such is life.

 

I wonder if anyone honestly has had consistently positive results from "fixing" small percieved defects like this.  My experience has been no.

 

Larger-scale problems, yes, such as wood 1mm too thick, or bridges/soundposts poorly done... but not with localized oopsies in the body, far from the bridge/soundpost.