Bridge fitting..

[Joey Anchors]

After upgrading my tuner machines on the MD404 I noticed my bridge feet aren’t making full contact with the top. In the attached photo you can see the gap (there’s light that passing through that gap as well)


Should I have the Brekke Bridge feet fitted better or is this normal?

[Manfred Hacker]

Should I have the Brekke Bridge feet fitted better or is this normal?

Normal?
No, this is terrible!

[Joey Anchors]

Normal?
No, this is terrible!

Those were my thoughts when I first took the strings off.

Does anyone have suggestions on fitting a Brekke Bridge? I know there isn’t a bridge rig for this type of bridge sadly.

[Br1ck]

First of all you need to take a look at it with string tension on the bridge. A top will flex slightly under tension. If it's still not making contact, what I do is slacken the strings enough to remove the bridge, place a fresh sheet of sandpaper face up on the top, put the bridge back on, put some tension back on the strings, and work the bridge back and forth across the sandpaper. You can't put full tension on the strings and work the bridge.

Those that do this a lot can apply down pressure with no strings on to simulate string pressure. Just be careful not to rock the bridge front to back while you do this. Plus you need a few extra e strings you are bound to break while doing this.

[RustyMadd]

First of all you need to take a look at it with string tension on the bridge. A top will flex slightly under tension. If it's still not making contact, what I do is slacken the strings enough to remove the bridge, place a fresh sheet of sandpaper face up on the top, put the bridge back on, put some tension back on the strings, and work the bridge back and forth across the sandpaper. You can't put full tension on the strings and work the bridge.

Those that do this a lot can apply down pressure with no strings on to simulate string pressure. Just be careful not to rock the bridge front to back while you do this. Plus you need a few extra e strings you are bound to break while doing this.

That is perfect advice. I would use 100-200 grit and as Br1ck said above, trap the paper between the bridge bottom and the mandolin top and just slightly wiggle/slide the bridge to fit the feet.

Great advice Br1ck
Blessings and good luck, you should be able to do this job yourself and the experience will be yours.

[Hendrik Ahrend]

I get best results, when I use the sand paper mainly to mark, where I need to take wood away. I then scrape (with a sharp pocket knief) or cut (with a small chisel) wood off the base of the bridge - repeatedly - and check with the sand paper in between and go basically as Brick describes. In order to prepare for string tension, I also found it practical to shape the bridge so that the ends touch the top first, in effect leaving a hairline gap in the middle, which closes when strings are tightened.

[Rodney Riley]

Did you mark (put some blue painters tape around the bridge) before you took it off? I would string it back up and set the bridge in place and get the intonation right. Then see how it fits the top. I’d make sure the bridge is in the right spot before doing any sanding and find out I was off an 1/8 or 1/4 inch and my newly sanded bridge actually doesn’t sit flat right where the intonation is perfect.

[Folkmusician.com]

Having attempted to train quite a few people in bridge fitting, I can tell you that the big mistake is not using enough downward force.

I too use sand paper mostly for showing the high spots, then a scraper or knife to remove wood. Back and forth, over and over. Some mandolins are much more difficult than others, it just depends on the top.


Strings are left on to speed up testing.

Sand paper across top. Pull tight with fingers and thumb. Use enough force to keep it contoured but don't snap the wings off the top.

Then small movements side to side with the bridge foot. A good deal of downward force to simulate string tension. Pull off, scrape, repeat.

Periodically check foot fit directly on the top.

[dadsaster]

Make sure you check your intonation before you fit the bridge and after. I find it easiest with half of the strings on.

[Br1ck]

You can use graphite paper to mark the high spots if you want. There are YouTube videos showing the process. Don't worry if it takes a lot of time to do your first one. When I wanted to play a Kentucky 1000 at the Mandolin Store,mit had just come in, they set the mandolin up in about ten minutes. Took me two hours the first time.

So Robert, you said attempting. Were you teaching efforts futile?

[soliver]

I created a bridge fitting tool similar to the one sold by Cumberland Acoustic... But I'm not sure it will work for a Brekke bridge.

This thingy:
https://cumberlandacoustic.com/wp-co...4842250252.jpg

[pops1]

I have the Stu Mac bridge fitting tool, similar to what soliver made, I don't use it and prefer side to side. I clamp a guide to the rims of the mandolin that has an arch in it so it doesn't come in contact with the top, only at the rims, and I can slide a piece of sandpaper under it. I use that for a guide to go side to side in the proper place without skewing the foot. I also use a piece of wood with holes drilled in for the studs in the foot of the bridge to go into. It is an inch or so tall and about the thickness of the foot and slightly longer than the saddle. This allows me to guide the foot while creating a fair amount of downward pressure at the same time. As others do I scrape the foot also and don't rely on the sandpaper alone. This allows a faster fit without the worry of tipping the foot forward or back, slightly angling the foot, or changing the location.

[Folkmusician.com]

So Robert, you said attempting. Were you teaching efforts futile?

In short, yes. Or at least when it came to consistency. Mandolins with difficult arching presented the most problems. I guess it makes sense. They take me three times longer and I have fit over 1000 per year.

[Ivan Kelsall]

From pops1 - " As others do I scrape the foot.. ". When i fitted a CA bridge to my first Lebeda mandolin,i'd heard of that technique ( i wasn't a Cafe member at that time),but i found that even the sharpest blade that i had in my home wouldn't scrape a molecule from the bridge base,so it was wet & dry paper all the way - i got it done & achieved a good fit,
Ivan

[HoGo]

...... i found that even the sharpest blade that i had in my home wouldn't scrape a molecule from the bridge base.....
Ivan

What about taking the blades to that W&D paper and sharpen them in the first place ;-) makes them good for slicing soft bread as well :-)

[Stephen Perry]

Scrapers. 45 degree bevel, very even and sharp, turn a crisp hook. Need a slightly curved edge. If very tough, lightly wet the ebony.

[Jeff Mando]

Experienced violin bridge fitters, use a knife/scraper and LITERALLY take about 30 seconds to fit a bridge. Obviously, a mandolin is not a violin and the bridge base is much larger. Sanding seems to take forever, but slow and easy is the best approach, sometimes taking hours. There is the additional problem of oversanding, which you want to avoid and if you don't use a jig, you need to make sure you are holding the bridge perfectly perpendicular to the top -- which I see as the main challenge.

[pops1]

It takes me much longer than 30 seconds to fit a violin bridge, but the reason for using a knife (sharp) or scraper is that a sanded surface is not smooth, leaving a fuzzy surface. Cutting with a knife or scraping leaves a smooth surface that is much better contact for sound transference.

[foldedpath]

The best luthier/repair tech I've dealt with (Cat Fox), maintained that scraping was the only way to do it right, because the sandpaper technique inevitably rounds the corners. Maybe applying enough pressure avoids that, I dunno. And you could probably get an equivalent to a smooth scraped surface with the right progression of sandpaper. But if you're going that far, then scraping might actually be faster anyway.

[Br1ck]

If you don't already, take a single edge razor blade and run a small round file across the blade at a forty five degree angle. Makes a dandy scraper for small shaping jobs like braces and bridges.

[sblock]

Abrasion, performed by sanding and polishing, is capable of getting at least as smooth a surface on wood as any type of scraping can -- in fact, even smoother, if so desired. It is simply not true that sanding always leaves a "fuzzy" surface! It all depends on the succession of abrasive grits that are used. If the wooden surface appears fuzzy, then you didn't go to a high enough grit number. You can even make the under-surface of the bridge glossy, if you're willing to be patient, and to use the finest abrasives. But, of course, this extreme is totally unnecessary for proper bridge fitting.

It's equally untrue that sanding "inveitably" rounds the corners of the wood base. That depends on whether you manage to keep the bridge properly perpendicular to the top at all times while performing any sanding (a jig certainly helps in this regard), and whether the sandpaper manages to stay flat against the top plate. If you manage that right, there is no rounding.

As others have stated, one advantage of bridge sanding is that it's much easier to control the amount of material that gets worn away (and where). With a scraper, you can easily go too far with a single misplaced stroke. But hey, do whatever works best for you, I say!!

[Folkmusician.com]

I fit two bridges today with sandpaper and scraper. The sandpaper only rounds the ends if you use strokes that are too long or do not have enough downward force. It really comes down to the downward pressure and adjusting technique depending on the arch of the top. Sometimes you can only move it 1/16". Other times 1/2" is fine.

I should note, I am using the scraper for material removal so I can limit the sanding. This is specifically to keep from rounding corners. The sanding is to mark the high spots and then get a final close fit.

[darylcrisp]

I have the Stu Mac bridge fitting tool, similar to what soliver made, I don't use it and prefer side to side. I clamp a guide to the rims of the mandolin that has an arch in it so it doesn't come in contact with the top, only at the rims, and I can slide a piece of sandpaper under it. I use that for a guide to go side to side in the proper place without skewing the foot. I also use a piece of wood with holes drilled in for the studs in the foot of the bridge to go into. It is an inch or so tall and about the thickness of the foot and slightly longer than the saddle. This allows me to guide the foot while creating a fair amount of downward pressure at the same time. As others do I scrape the foot also and don't rely on the sandpaper alone. This allows a faster fit without the worry of tipping the foot forward or back, slightly angling the foot, or changing the location.

Pops
would love to see a picture of this in place, I think I have the idea in my head, and if it is how I think it is, it sounds like a solid easy to use guide.
thanks so much
d

[darylcrisp]

some well thought out processes above. some things to definitely try out next time.

to the OP, make sure you didn't turn the bridge around when putting it back in place-that can happen easily and the outward feet will look like your picture. usually on the weber bridges(if this is a bruce w issue) you will see a G pencil marked for that string course side. the "saddle" can be flipped and will fit either direction if it was removed, so check your bridge before you reshape.

d

[dang]

Frets.com explains this rather well...
http://www.frets.com/FretsPages/Luth...t/fitfeet.html