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A few restoration questions:

 
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S. Stewart
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Joined: 25 Apr 2007
Posts: 3

PostPosted: Wed Apr 25, 2007 10:56 pm    Post subject: A few restoration questions: Reply with quote

Hi,

This is my first post here too, so I'm also introducing myself, ... hello! I'm an engineering student with a strong intrest in guitar repair and am new to violins.

Recently I got the opportunity to restore my great great grandfathers violin that he built. It's not a very fancey violin, and may have been built from a kit, but to me it's still very exciting. I want to get it to a very playable condition, and cleanup the major problems.

There are 3 main areas that I think need the most attention, and I'm looking for some advice.

1. On the back, near the bottom, the seam looks more defined then it should be, and I'm thinking that it might need to be filled. I am wondering if there are ways to determine this for sure.

2. Where the brige normally sits the finish has been worn away to the wood. I don't want to refinish the whole violin, but would like to properly repair the area so it doesn't get worse. I'm curious to know if there are any standard ways of cleaning this up.

3. The violin came with two bridges, both with there own problems, I am wondering if it would just be better if I got a new bridge instead of trying to salvage one of the older ones.


Thanks for your time and I appreciate any advice.
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Mat Roop
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Joined: 24 Mar 2007
Posts: 911
Location: Wyoming Ontario

PostPosted: Wed Apr 25, 2007 11:51 pm    Post subject: Reply with quote

Hi S....
1- depends... if you are referring to the seam where the two halves of the back are joined, test it gently by pressing on one side of the seam... in good light conditions you should be able to see if one side flexes independently of the other... if they flex in unison, I would leave it as is... the less you mess with things the better.
If you are talking about the seam between the back and the ribs, test it by tapping lightly with the back end of a small screwdriver... if the sound is disinctly hollow compared to other ares, then the seam is open. If so, you need to open it it with a thin knife, work in some clean hot hide glue and clamp.... dont let drips of glue dry on the varnish or it will pull it off and make a real mess!
2- The theory is that varnish under the bridge feet will dampen the transmission of vibrations to the body. Old timers often removed the varnish under the feet to get a better sound...I would leave this as is unless there is serious damage
3-I am not sure what the bridge problems are, but yes I would likely fit a new bridge...but there is alot to fitting a bridge....check out this site....
http://www.violinbridges.co.uk/ref.php?link=main#

When you have specific problems... it is always nice if you can post a pic of the issue...but if you can't that is Ok too.. in any case let us know if you need more info!
Cheers and goodluck!
Mat
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S. Stewart
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Joined: 25 Apr 2007
Posts: 3

PostPosted: Thu Apr 26, 2007 1:32 pm    Post subject: Reply with quote

Hi Mat. Thanks for the response.

The seam is where the two back halfs are joined. I tried pressing on it to flex it, but it is near the sides so it was difficult to tell if it was flexing at all. When I tap near it, it sounds different, but not hollow. I don't want to make things worse so I am tempted to leave it, but I don't want it to affect the sound of the instrument. Structurally, I think there is no problem if it was left the way it is.

There is no damage where the varnish is missing, and it completely makes sense for that to be the reason. My great great grandfather was apparently quite the old time player, he held it against his shoulder instead of under his chin, fiddling on it and stomping around.

To expand on what I was saying before with the bridges. There are two that came with the violin, neither have cracks in them, but they are really different from each other. One is a good 3mm shorter and slightly flatter on top but the treble side isn't lower than the bass. Why I was thinking about getting a new bridge is because the notches on top of both of these bridges are very worn in, and I could see the string buzzing and having interference problems.

If I can, I'll post some pictures later today. I was looking at the bridge info that you posted. I agree it does look really involved, I have the time and the tools though, so if I needed to, it could be fun.

Thanks again!
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Jeffrey Holmes
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Joined: 03 Apr 2007
Posts: 90
Location: Ann Arbor

PostPosted: Thu Apr 26, 2007 1:45 pm    Post subject: Reply with quote

S. Stewart wrote:


I don't want to make things worse so I am tempted to leave it...


Good idea. That particular repair can be a bit tricky (depending on the cause of the separation). Unless you've manipulated a back center joint before, there are plenty of chances to make things (much) worse.
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Ed
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Joined: 02 Apr 2007
Posts: 17
Location: Merrimack, NH USA

PostPosted: Thu Apr 26, 2007 3:40 pm    Post subject: Reply with quote

Jeffrey, could you elaborate on methods to repair an open back seam? I have one to do which is open starting below the upper block to about 1/3 the back length. Top off, no doubt, or perhaps back off? Getting the edge surface to be flush with one another has always been a big challenge for me. - Ed
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Jeffrey Holmes
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Joined: 03 Apr 2007
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Location: Ann Arbor

PostPosted: Thu Apr 26, 2007 5:52 pm    Post subject: Reply with quote

Hi Ed;

As I’m relatively new to this board (and I'm not sure how many here know me), I’d like to explain one thing before I make a comment on the repair (a disclaimer?). I am aware that there are several ways to approach repair procedures… and that following some of my suggestions may lead to spending more time on instruments that may not be “worth” the effort of going through what I describe…That’s the defining point for what I’m willing to work on (that it’s worth doing the job correctly)... but I’m in the position that I really need not take all comers… I choose what I work on (and who I work with). Earlier on, when I was learning repair techniques, I looked at less expensive instruments as an opportunity to learn more complicated techniques… and I figure everyone won (I learned, the instrument got more and better attention than it otherwise might have and the owner-if not the shop I was working for- often got more than their money's worth). I also understand that some in the industry are in the business of holding less expensive fiddles together, so to speak, for school programs, etc. In this case, following my lead is probably a great way to go broke.

I say all this, as often I'll describe a procedure that is over the top for some... If that's the case here, sorry!

OK, enough of the boring stuff. Back joints:

The approach is dependent, to a large degree, on the cause of the problem. Back joints rarely just “let go” for the heck of it. The joint fails for a variety of reasons including stress, shrinkage, a poor initial joint or unstable wood (similar to shrinkage but more complex). I can’t see yours (without a photo), so I’m shooting in the dark here…

The wood-to-wood contact should be checked first. If it’s a simple failed joint (no stress), it may be simply a case of gaining enough access to line up the halves and glue the joint. If the joint was starved or the glue was weak, the failure may have been present in the build. Check the joint to make sure that it is free of varnish (if the joint was open at the beginning, some will have traveled in). It is often possible to reglue joints with good contact by removal of the top (for access), possibly loosen one or two of the bouts on the back, and use of strap clamps in combination with towers/wedges/clamps for alignment issues (see "Invisible seams?" thread)… but in your case, the fingerboard may be a nuisance. If it will be in the way, you’ll need to consider removing the back.

BTW: I'm not big on clamping joints or cracks from above and below to align them... Problem with this is, hot glue will swell the wood around the opening when applied, so if you squeeze it with a clamp, it compresses the swelled wood, which will often still contract as the glue dries, leaving a small gully. I much prefer using towers or "zipper" style cleats (one cleat glued on one side of the crack, the next on the other) for alignment.

If there is any significant gap in the center portion of the open joint, or there is distortion, the job is more complex. I’d remove the back. I use jig with a flat surface to ensure that closing the gap will not cause the plate to cup or curl (as it will simply re-open, or cause a new problem, due to stress when the back is re-attached and flattened back out). With the back removed, it’s also possible to set up a clamping system with pins and wedges (again, see the "Invisible seams?" thread) to aid your strap clamps.

If the gap cannot be closed by use of reasonably gentle pressure without causing the plate to cup or curl, it may be that wood will need to be removed from one end of the joint (which will allow the gap to close). In more severe cases, (multiple openings, severe cupping, other difficulties), rejoining the plate may be necessary… but this requires a bit more complicated setup.
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Last edited by Jeffrey Holmes on Fri Apr 27, 2007 12:34 pm; edited 1 time in total
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Mat Roop
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Joined: 24 Mar 2007
Posts: 911
Location: Wyoming Ontario

PostPosted: Fri Apr 27, 2007 12:47 am    Post subject: Reply with quote

a couple more thoughts....
I had a client with a sentimental violin with a split back seam ( about 1/2 of the lower bout length) (apparently it had been stored behind a furnace in a basement for 25 years)... but she wanted the repair so she could display the violin and did not want to spend the money to do it right... Although I tend to fuss well beyond reasonable limits to "get it perfect", I agreed in this case to just make it look good.... but I could not pass the opportunity to experiment without removing the top or back. The separation was right past the end block and the purfling was still intact
I cleaned the seam by running the thinnest 400 grit paper thru the split, separated the tail block and 1/2 of the lower bout ribs from the back. I tested by dry clamping and realized the two halves just would not pull together. Considering this was a "non-musical" repair I proceeded with gluing the seam by rubbing in a fairly thick hot hide glue and clamping as best I could. In the morning, I was absolutely amazed that the glue had pulled the seam visibly tight and seemed real secure. I now have a greater appreciation for the ability of hot glue to expand the wood with the moisture, and then draw it together...I use a 260 gram bloom strength hide glue.

and S... re the bridges... the standard curve of a violin bridge is about 42 mm radius, but for fiddlers the norm is in the order of 47-48 mm. Check the height of the bridges relative to the fingerborad projection. The finished bridge should be in the order of 32 to 33 mm high and at that height, the clearance of the strings above a normally scooped fingerboard end should be 2.5mm for the e and 4.0mm for the g

I try to avoid removing backs... you can quickly get into big trouble with the button... I always work from the top... including removing the fingerboard.
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Jeffrey Holmes
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Joined: 03 Apr 2007
Posts: 90
Location: Ann Arbor

PostPosted: Fri Apr 27, 2007 10:33 am    Post subject: Reply with quote

Mat Roop wrote:
I try to avoid removing backs... you can quickly get into big trouble with the button... I always work from the top... including removing the fingerboard.


Back removal can be tricky, and I agree it's best to choose the least invasive procedure available to accomplish the job in the best possible manner... That said, in my opinion, if the best way to accomplish the job means the back needs to come off (which it sometimes does) and you don't feel up to it... best to refer the job on.

Yes, Mat; Hide glue can do some pretty amazing things (like pull joints together). The trick is to be able to predict what it will or won't do. Smile

An alcohol lamp or other heat source can also come in handy closing up cracks...
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Ed
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Joined: 02 Apr 2007
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Location: Merrimack, NH USA

PostPosted: Fri Apr 27, 2007 12:31 pm    Post subject: Reply with quote

Thanks for your reply, Jeffrey. I appreciate the help.
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Mat Roop
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Joined: 24 Mar 2007
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Location: Wyoming Ontario

PostPosted: Fri Apr 27, 2007 5:44 pm    Post subject: Reply with quote

Jeffrey Holmes wrote:

An alcohol lamp or other heat source can also come in handy closing up cracks...

Jeffrey...I have not tried the heat technique... what is the essence? My first reaction would be that heat would dry and shrink the wood thus pulling the crack apart....obviously I am missing something. I use heat but only to heat up the parts to prevent the glue from setting too quickly.
Cheers, Mat
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Jeffrey Holmes
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Joined: 03 Apr 2007
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Location: Ann Arbor

PostPosted: Fri Apr 27, 2007 5:53 pm    Post subject: Reply with quote

Heat works well when you have the ability to bring the crack closed relatively well by clamping... not to "suck" or swell an open crack or joint closed. Once glue is applied and the clamps are on, heat can sometimes help make the crack "tighter (tight glue line).
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S. Stewart
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Joined: 25 Apr 2007
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PostPosted: Fri Apr 27, 2007 6:59 pm    Post subject: Reply with quote

Wow, this thread seems to be doing well.

Thanks for the advice Mat, and others. I was thinking of putting the strings on loosely as I fitted the bridge, is this a normal practice? or shouldn't I try it?

I've finished making the initial bridge design, and now it needs to be properly tuned (feet, strings), so I'm thinking this would help.
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Mat Roop
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Joined: 24 Mar 2007
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Location: Wyoming Ontario

PostPosted: Sat Apr 28, 2007 12:07 am    Post subject: Reply with quote

S... we are here to help!
I fit the feet of the bridge first without the strings...ie the thickness and the mating to the top
Then I mark the top about 1-2 mm higher than the estimated final height and shape it to the right curve and mark the string notches, file and lubricate grooves with pencil graphite.
Next I install the strings to tension and then start to make the necessary ajustments, check sound production, elevation above fingerboard etc. A string lifter is of immense value in this process:
http://www.violins.ca/tools.html
8D-4501 String lifter, violin/viola

You will take the bridge out maybe a dozen times before you are satisfied...and I generally do it over two nights.. 1st night almost right and then by the second night things have settled in for the final ajustments.

Cheers, Mat
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