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Flusg Bridge Feet


keyboardclass
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If you intend to cut bridges regularly, then don't bother with sandpaper. It will take you far longer and won't work towards proper tool work that you need to learn. If you want a shortcut on the roughing you can use a 3" sanding drum in your drill press and follow the line that you scribed (should take about 30 seconds to get rough fit), then follow one of the knife or chisel fitting methods described in the recent thread that Ben mentioned. I think it was Properly Fitting Bridge Feet or something like that. I think there are numerous threads on the subject, though.

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I woulnd't go near a sanding drum with a violin bridge.

Yeah, I think that was my first thought when I was expected to rough fit with a drum sander and finish fitting with a chisel in a shop that did high volume setup in an assembly line of sorts. The demonstration of a 5 minute hapless bridge fit was compelling, but it took me quite a while to get the hang of it. The drum sander lets you match your pencil scribe line square to the back of the bridge in about 30 seconds and from there you fit as normal. It's just for rough fitting, not acceptable without finishing with a knife or chisel.

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I virtually never see those "perfectly" knife fit bridges. I guess they avoid my shop.

I would think that there is an abundance of perfectly fit bridges using a knife or chisel. At least that's the case in my area. I'll post one tomorrow. I can't imagine achieving the same thing with sandpaper. Certainly couldn't be as fast as a blade in the hands of someone accustomed to fitting that way.

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Speak for yourself. You just have to know how. And I virtually never see those "perfectly" knife fit bridges. I guess they avoid my shop.

 

This bridge is a standard quality bridge for 'step up' or higher end factory violins in our shop.  It is fit with a chisel, and I'd say it's pretty typical of what I expect from knife or chisel fit bridges from professional luthiers. Photos were taken with the strings slack, so there are no gaps pressed out by string tension.  There is a little bead of varnish that obscures the line of the bass foot, so it's hard to prove the gapless fit on that side.

 

post-78210-0-61840500-1456773083_thumb.jpg

post-78210-0-07110300-1456773109_thumb.jpg

 

No idea why these photos are posting upside down.  This has happened to me once before, and I'm at a loss as to why that would happen.  The photos open right side up on my machine.  Last time this happened I tried flipping the photo and uploading it, and the photo still flipped.  I tried it both on my iPhone and on the PC, and it's flipped on both machines.  Either way, I'm sure you get the idea where fit is concerned.  Has anyone else had this issue?  Any explanation or remedy for this?

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At the risk of being accused of shameless self promotion, here is a tool I have developed.... works like a charm and saves a ton of time ( for me anyway) . The key difference is that the bridge is stationary in the EXACT same position during during each test of fit... even if you use sandpaper, which I don't really recommend.. but it does work for student fiddles.

https://www.violins.ca/info/violin_bridge_fitting_tool.html

Could not resist posting the link... my apologies :unsure: ... cheers, Mat

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Keyboardclass,

 

Have a look at this thread. I asked the same question about a month ago. With tips from members I was able to get a perfect fit with a knife and a chisel. it took e a couple of goes but i was able to do the whole bridge in about 45 min. There is no way to get around it, this is one of those things that just requires practice. 

 

good luck!

 

Chris

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New violin, soft varnish, hollow feet, no problem!!! :lol:

 

attachicon.gifhollowed bridge feet.jpg

 

Bruce

Hollowing the underside of bridge feet certainly increases the pressure on the varnish by at least double... but I have many times heard of this being done ... not to the extent of the pic above, but done nonetheless. 

Is this practice strictly an amateur venture in the arena of folklore, or has it been done professionally with some evidence of benefit to tone?

 

cheers, Mat

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I think Bill Fulton, well known VSA maker, suggested bridge feet should be slightly rounded cross axis because bridges never stay vertical. Makes sense.  Also, I think a summary of this subject would be to use whatever method will shorten this task.

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The drum sander lets you match your pencil scribe line square to the back of the bridge in about 30 seconds and from there you fit as normal. It's just for rough fitting, not acceptable without finishing with a knife or chisel.

 

I have been able to get a near-finished fit from a drum sander... but only for my own fiddles where the cross arch of the top (at the bridge location) was made to an accurate radius (chalk-fit to a radius gage).  Then I can use my radius fixture on the drum sander to match that curve.  All that remains is to use a light scraper to take off the scratches.

 

In general, though, I agree that the drum sander would only be for hogging off the bulk of the excess wood, and that other ways of using sandpaper to fit the feet will not get a good fit, as it almost always rounds off the edges to some degree.

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Hollowing the underside of bridge feet certainly increases the pressure on the varnish by at least double... but I have many times heard of this being done ... not to the extent of the pic above, but done nonetheless. 

Is this practice strictly an amateur venture in the arena of folklore, or has it been done professionally with some evidence of benefit to tone?

 

cheers, Mat

I'd call it an amateur thing. I can't think of even one highly successful pro who does it.

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Well, I certainly don't see a perfect fit in those pictures. Must be a difference of definition. I can easily do better than that by sanding. Of course, visible fit is only part of the problem. I'm more interested in full-foot fit, best judged (in my opinion) by the impression left in varnish. But I'm just a hobby maker.

 

Hi Captain.  I find "perfect" is a matter of degree, but a well cut bridge foot should fit extremely well.  I use chalk impressions for final fitting, but others use carbon paper, or graphite, or china markers. I haven't seen a fit I find acceptable accomplished by sandpaper, but if one put their mind to it, they might come close on a new fiddle.  For older instruments that have indentations from the feet already (in the wood and/or varnish), I don't think I'd be sticking my neck out too much to say it would be damn near impossible to obtain a good enough fit with paper.

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Well, I certainly don't see a perfect fit in those pictures. Must be a difference of definition. I can easily do better than that by sanding. Of course, visible fit is only part of the problem. I'm more interested in full-foot fit, best judged (in my opinion) by the impression left in varnish. But I'm just a hobby maker.

 

Well I can see how you might not be able to see the difference between some of the varnish that is pushed up around those feet, and a gap.  It's clear to me because I saw the original before taking the photo, but looking back I can see that the photo is just not clear enough.  I'm sure I could find a better example, but that was just what was on my bench when I was thinking about it.  I can't see any way that you'd be able to get a sandpaper fit that leaves you with a bridge that can stand without pressure and have no gap on either side, particularly if there is any disturbed varnish.  Then again, seeing is believing, so post a photo of a bridge without pressure, and we can see how well it fits.  The impression left in the varnish isn't a good gauge because previous bridges will have left their mark.  The first bridge in particular often leaves an impression, and anything that comes after will need to conform to the surface that exists.  The varnish may have gotten harder since that first bridge, so any impression may be misleading.  Best to assess the fit of the bridge by how it stands in position without string pressure, and whether it has any rock or tilt.  Of course hollowing out the middle is not an acceptable way to achieve that, and graphite, grease pencil, or chalk are common ways of ensuring that you have a fit across the entire surface of the foot.

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