Bridge warping


Recommended Posts

Regarding the 'chest' on the tailpiece side of the bridge, I leave violin bridges flat (and approximately perpendicular to the top) up to about the level of the heart, then file away 0.25-0.30 mm at the top (sometimes slightly more on the treble than the bass side). I check this by holding a small straight edge against the tailpiece side of the bridge (vertically) and judging the gap at the top. The front of the bridge (fingerboard side) is definitely thicker in the center than at the edges, and ends up with a thickness of 1.2 mm at the top edge. I echo Jeffery's opinion that only the player can prevent warping-I always demonstrate how to judge and maintain proper bridge position to everyone taking an instrument from my workshop, and try to remember to provide positive reinforcement to those who do a good job as well as remedial advice to those who don't.

Link to post
Share on other sites

Thanks for the link, Michael! I forgot about "squeeze the banana". :)

OK... I've got a full day, but will take the time to post this before I jump in. Lest we get carried away comparing the arch on the back of all bridges based on my comments, the original OP asked about minimizing warping especially on 'cello bridges. My first post in reply concerned that... 'cello bridges. While bridge cutting is, well, bridge cutting, I think 'cello bridges are a case-set all on their own. As I mentioned, these days most 'cellists are using steel core strings and 4 fine tuners and a majority prefer Belgian style bridges. The strings and tuners add complications of stress on the bridge. The tension of the modern strings aside, the bridges are being "pulled back" by tuning at the tailpiece, and pulled forward by the tuning at the pegs. For stability sake, I've increased the relief on the back of the bridges (I do more than I used to) and changed the style of the cut (I've strived to make the legs more vertical/parallel on my Belgians, left a tad more in the "hip", and strive to lower the position of the heart just a bit) in an attempt to increase the stability. It seems to work well, and a bonus... I like the sound better in almost all cases. The shaping of the edge of the bridge is done in a way that, unless you knew I relieve the back and you were looking for that feature, you might not notice.

Now. Violin/viola bridges. Yes. I slightly relieve the back of these bridges as well (not as much as I relieve the 'cello bridges), above the heart, and with the same deceptive treatment at the edge. I do usually end up planing both sides of the blank, taking off the bridge manufacturers stamp, as I like to fine tune the grain orientation.

Many do things similarly. Some do not. I took out one of my bridge boxes and checked about 20 bridges this morning. The majority were slightly relieved, though a there were some nice bridges by notable shops there that were made with a flat back. A few of these were concave from use, a few were not. Fewer of the slightly relieved examples had this particular problem. This tells me, like is true for many things, that there is probably more than one way to "skin a cat" (as the saying goes), and one has to find methods that are reliable and reproducible for oneself.

I've stayed away from the issue of wood quality. That's a subject that probably deserves it's own thread.

post-17-0-36751800-1318596923_thumb.jpg

Link to post
Share on other sites

Thanks for the info.

I typically leave the back of a violin bridge flat, remove a tiny bit from the back on a viola, and about 20% off the back of a cello bridge.

I'll try "chesting" the back of a violin bridge next few I make.

I've gone through some old violin bridges from various maker I've collected, and it seems to be about 50/50 flat backs vs rounded.

Here are a few pictures of one of my recent bridges. Comments are welcome.

Thanks!

post-24710-0-70398900-1318602540_thumb.jpg

post-24710-0-37992300-1318602563_thumb.jpg

post-24710-0-74009000-1318602575_thumb.jpg

post-24710-0-22137600-1318602589_thumb.jpg

Link to post
Share on other sites

Comments are welcome.

Thanks!

You have a bit of that bullet shaped thing at the edge going on the arched side of your bridge. Changing this aspect would probably give you a slightly more graceful look, if you care. Also, it depends on the fiddle & the wood of the bridge a little, but the "chest" seems to extend up toward the string edge (top) just a little far for my tastes. I think the strength provided by the chest is important just a tad bit lower.

Also... a suggestion when doing bridge study... when comparing what other bridge makers do (relief or no) I think it's important to note "who" made the bridge (if the shop has a good rep) and how it stood up to the test of time (not that you need to tell us, just note it personally). In other words, what shops like Hill, Beare, and Wurlitzer did is more important to me than what some others might have done. If you decide to go off in one direction or another, knowing what the classics looked like will give you a good point of reference.

Link to post
Share on other sites
  • 4 years later...

Making the back perfectly flat means you can detect any warp more easily, putting
a chest on it means you can't detect that so easily. 
I put a small chest on all bridges partly to centre the strings over the mass of the bridge, but also to give the bridge a second chance, should it move a little either way. 

Main thing with Cello bridges is good legs, but then I always preferred legs.

Link to post
Share on other sites

I put a bit of shape on my bridge backs too, for all the same reasons as everyone else, but also I think a completely flat bridge back can look hungry.

 

I question the grading of bridges by their figure. I often find that the plainer grades of bridge blank are much better than the fancy ones. Most of the cost of a bridge is in the cutting, and I've never had a client complain about having too few medullary rays, so I don't worry about the grading at all, and make my own decisions.

Link to post
Share on other sites

I do it dry on a hotplate, with a piece of paper between. 

 

Occasionally I dampen the bit of paper, but I don't like to, and the steam can burn your fingers! I once left a bridge there on the plate, and answered the phone. Not my most intelligent moment - an extremely expensive piece of toast.

 

Some people use a heat lamp. They say they just give the bridge a blast and it straightens up -  I don't know, I haven't got one.

Link to post
Share on other sites

Ben,

 

I use a clothes iron on all violin and some cello bridges. Cello bridges take a while to heat through. Someone else once mentioned first heating bass bridges in a microwave oven. I've tried that with very good results. Probably would work well on cellos too.

 

Note: my microwave is a small 700 watt model. Do it gently.

Link to post
Share on other sites

Regarding Cello bridges, I've noticed that if they warp, the top bends toward the tailpiece rather than towards the fingerboard. I don't really understand why, as was pointed out, the angle between the string and the Bridge is smaller on the tailpiece side, I'd expect the tendency to be in the other direction. Also, considering how sacconi type tail Cords Stretch, I'd expect that would contritrube to a bending toward the fingerboard. But I have seen that happen only once or twice and only on incorrectly stored Cellos that were unused for a very Long time.

 

I'd also like to add that Student Cellos I meet on a daily Basis all have this Problem of warping toward the tailpiece, starting day one. However, I had one 1/2 size Student Cello Setup adjusted by another lutier than the one that usually does Cellos of my students, and the only Thing they did to the cheapo Bridge was correct the fit of the feet, nonetheless, this Bridge has kept straight as a candle, better than any other Student Cello Bridge I've encountered so far. So I'm suspecting warping on Cello Bridge has a lot to  do with the fit of the feet too. And also: cheap bridges can stay straight and work well if the work done on them was done properly.

 

btw I hate Auto correct!

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Recently Browsing   0 members

    No registered users viewing this page.