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Three13

Bass bar question

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1 hour ago, jezzupe said:

google "ultrasonic thickness gauge"....they have ones as cheap as 100$....the one I looked at did metal, pvc,glass and such, I assume it work on wood too.

I ended up borrowing a friend's gauge. 

The question now is whether there I can find anyone good willing to take on this sort of work. I imagine that the whole "angels fear to tread..." cliche applies to regraduating violins.

 

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On 8/12/2019 at 2:55 PM, Three13 said:

That’s the plan - if anyone has a recommendation for a source for a Hacklinger gauge that won’t break the bank, let me know. 

I have one of these.   With some care in use, they are fairly accurate.

magnetic thickness caliper

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1 hour ago, Three13 said:

I ended up borrowing a friend's gauge. 

The question now is whether there I can find anyone good willing to take on this sort of work. I imagine that the whole "angels fear to tread..." cliche applies to regraduating violins.

 

I think with good communication that this is a pretty straight forward. I think in most cases like this a repair/modifying  luthier is perhaps more afraid of the clients expectations that the actual job itself.

Meaning you seem somewhat convinced that a re grad would improve it, and it may, but it may not, and if it does not how would you take that?, is it the luthiers 'fault it doesn't sound better? do you think "well maybe if someone else did it it would have worked? 

And so lots of gets into you understanding that you're paying someone for an attempt , not a guaranteed improvement, which would be subjective anyways....and that in all that, I think anyone who would attempt such things would know how to verbalize all that in a work order contract.

Or quite simply, ya, I'll pull it apart and thin it, but if it doesn't; sound better 1. I get paid either way 2. you don't bad mouth me after the fact for not being able to improve it

This by all accounts should be a simple job, BUT there can be lots of curve balls in this sort of thing...Right off the bat a common issue can be that a "properly glued" top is fairly easy to remove, thus making it so we can get right to thinning, BUT, maybe it wasn't properly glued on and someone opened it before and put it back with super glue. Then suddenly we have a job that can't be done  without lots of extra time before I even try to thin it

A good contract goes over every scenario and lets you know what will/won't/may happen so that no matter what the scenario or outcome no one get left feeling burned.

Some people may charge by the job, charge you an amount that virtually no matter what happens they will make a profit, others may do it by the hour,probably the most likely way you would be billed

 

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8 hours ago, Don Noon said:

I disagree.  Those are significantly thick graduations, especially the top.  If I assume normal-ish wood density and went to my usual graduations, I estimate that the plate weights would come down by a total of ~50 grams, giving an instrument weight close to the normal range.  Yes, it would be an absolutely enormous pile of shavings.

Having regraduated some brick-like student instruments with tops over 90 g, I feel this IS THE PROBLEM as originally stated, i.e. that the low end is anemic.  Taking that much wood out, particularly from the top, gives a huge boost to the low end.  

This is one example of the before/after impact response, where the low frequencies are 6-12 dB stronger (that's a LOT):

Regrad.jpg.aa4a890463d3fe28f62300ca4b5bb7ca.jpg

Looking at those results, there was an impressive change in the lower frequencies, and I agree that removing wood from the plates in the OP violin will improve the stifled lower register.

My feeling is still that something else may still be amiss afterwards. Although we have not seen pictures of the OP violin, it is described as well-made, and has already been re graduated previously, though it would seem that graduation attempt left a lot to be desired, and they were unsure of how a bass bar should function.

Given that the plates are still so thick now, I imagine that the ribs are overly thick too, hefty blocks and linings, perhaps a very thick fingerboard, and I suspect the wood is slightly above average in terms of the density. To get this instrument below 400g will require more than just thinning the plates in my opinion.
In the past you have posted some interesting information of just how much some types of finish weighed for example. But the 477g weight quoted can easily be skewed, if this violin happens to have a heavy ebony tailpiece with four steel adjusters, losing that would make a large difference in itself.

Until a lot of work is done, we won't know the final answer for sure. Ultimately, the OP has to decide if it is worth the cost to them, or if it might be prudent just to change the instrument.

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5 hours ago, Dave Slight said:

My feeling is still that something else may still be amiss afterwards. 

Absolutely... we don't have enough information to tell everything about this instrument, and what else may be screwey with it.  However, I think that from the weight and thickness measurements, if they are correct, appear to be the  major item causing anemic low end, and a good chunk of the extreme weight.  I wouldn't say that getting below 400 g is a reasonable goal for this instrument, at least by plate regraduation alone... there can be globs of fat many other places, as you say.  Most of those other places wouldn't affect the low end much, unless perhaps the ribs are 3mm thick, gigantic end blocks, or something like that.  Extremely dense wood is also a possibility.

In any case, this all supports the idea that if someone is going to take on this revoicing project, they really need to know their stuff, and be willing to tread in questionable areas.

 

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