How many ways to shave a bridge?

[tadej bratkovic]

I never came across any explanations how to actually lower the bridge itself.

Often times I would like to perform this type of setup, especially when saddle to bridge pin string break-angle is not sufficient or the guitar has high action, but the saddle's not protruding enough.

I was thinking about it a lot and still can't come up with a neater solution than sanding and filing it down. And, of course, endmilling the saddle slot if needed.

I thought that it would be easy with a plunge router base on a dremel with a 3mm endmill, using with a simple jig that one would put over the soundboard. But since soundboards are bellied, this method is very tricky to work properly, I'd say.

Recently I had a customer that badly needed a bridge shave. Outer strings had such poor break-angle that the piezo was just barely picking it up. I had to recommend another repair guy for this type of job. That guy apparently did it for $30. I haven't seen the guitar yet. The owner assures the problem is gone and of course I believe him.

I can't call the guy and ask him, these old-timers here are taking everything to their graves. Small country, handful of customers, but lots of repair people and private instrument builders lately. Seems like the old-timers are being annoyed on a daily basis.

Since everyone here always has a better solution to offer, or at least an alternative one, I wanna know what you do.

Thanks!

[Mark McLean]

John,

Yes, I agree that on a Taylor it would have been quicker, easier, and more aesthetic to adjust the neck.  However, we have to give it to whoever did this - it is a workable method.  There might be situations (cheap but much loved guitar, unworkable neck joint, ovation) where this is the best way around the problem.  Thanks for showing us!

[Hesh Breakstone]

Either a small, very sharp plane or a big-arse, aggressive file and high pucker factor....  We protect the tops, a good idea.

This idea of shaving bridges has it's applications such as that Epiphone that Frank mentioned or other instruments with a neck joint that is not serviceable.

What I hate to see though is something like a nice Martin that someone shaved the bridge on instead of doing a neck reset....  We see this far more than we would hope too as well.

Bridge shaving is clearly a Lutherie activity that the idea of "what's appropriate for the instrument" comes into play and I see that this has been mentioned already as well - good to see.

EDIT:  At times making string ramps can get you the break angle that you seek as well.  Again it's what's appropriate for the instrument.

[John]

Here's a manufacturers point of view on bridge planing. The link to the original article is at the bottom.

Question:

It seems many people have issues with low to no saddle left for adjustment.

This is what I have been told when I asked a very reliable source, Larrivee has used a thicker than normal bridge to allow the user to adjust the set up to their liking via a bridge profile. When I asked what a profile was I was told that the bridge material is removed to allow for more saddle height so the the saddle can now be lowered again. It just seems that shaving bridge material with the bridge on the guitar is a bit aggressive.

If someone can explain bridge profiling and how it is done that would be great.

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Matthew Larrivée replies

It's an issue that opens a can of worms for many people. As there are a group of "internet forum readers" who believe it is not a valid way to adjust the guitar. Both Jean and I, Taylor, Martin, Collings, and virtually every other maker disagree with them.

Our bridge starts off at around 10.5mm and you can safely take the bridge as low as 7.0mm with no loss in tone or stability. We basically use a rectangular orbital sander and some hand sanding to do it. We also manufacture special bridges (9.5, 9, 8.5, 8, 7.75, 7.5, 7.25, and 7mm) that we use for repairs. The bridge usually requires some extra dremel sloting to reset the string break angle as well.

The primary reason this is done is not that neck join has changed, but rather the back of the guitar has either swollen or collapsed due to moisture change which forces the neck block to slightly move in turn giving the apearance that neck angle has changed. For example I had a lady come in this week from San Diego whos guitar was swollen like a football. Her action was a mile high because the back of the guitar had swollen up shifting the neck forward. She had lowered the saddle and there no room for it to go lower. So we removed about 2mm from the top of the bridge and reset the break angle - the string height at the 14th fret went from 8.5/64th to 5/64th with room on the saddle to spare to try and get lower if she wanted. It's a quick and easy permanent fix that doesnt require the risks and damage of a neck reset.

http://toonz.ca/bose/wiki/index.php?title=Larrivée_Bridge_Height_Adjustment_vs_Neck_Reset

[tadej bratkovic]

Thanks everybody for contribution.

Yesterday I tried it for the first time with a budget quality small block plane. Did the majority with that, then filed, scraped and finally sanded it up to P600.

I didn't like the feel of a plane on the bridge and it actually quite tricky to control. I am going to try a block surform plane next time.

I think the reply from Larrivee made everybody's lives a little easier. :)

[Andrew]

Thats how budget planes usually perform. Ive never seen a cheap plane tuned to snuff out of the box, and many cannot even be tuned properly except for very general work. This is not 'general purpose' work.

I could also see how a normal block plane could be a little on the large side. Also, with ebony, the changing grain runout associated with cutting contours, the plane needs to be very, very sharp, and very finely set, especially for this kind of work. Using planes effectively requires a lot of experience and an intimate understanding of the tool and the wood. This isnt a situation for practising with, in short.

I might suggest a smaller rasp or a chemically etched 'razor file' like stew mac sell (more of a float really) for material removal rather than a surform if you want to go that route. Surforms tend to fight you the whole way through most hardwoods. Theyre just a simple man's plane really.

You'll never regret the price of quality hand tools if you learn to use and care for them properly. Hardware store stuff has a place, but usually the hand tool departments are quite lacking in precision and quality compared to 'real' tool dealers, at least around my parts.

[Paul Verticchio]

http://www.leevalley.com/US/Wood/page.aspx?p=70138&cat=1,41182

[Andrew]

Yes that one came to mind lol. Im very up to date on Lee Valley stuff. Drool over it all daily. I think that one would be a wee bit small for quick material removal in this case. Probably the flat squirrel tail palm plane would be the best balance of easily manageable size and efficient cutting, but of course this is subjective to the preference of the person doing the work:

http://www.leevalley.com/US/Wood/page.aspx?p=57205&cat=1,41182

One could use a myriad of these little detail planes on a job like this, one for each little function in the process of shaping. If I had my way, Id have the full Lee Valley selection at ready disposal for these situations. And a few Lie Nielsons as well. But of course I like fooling with my tools as much as actually getting things done :P (if not more so!)

[Paul Verticchio]

Hi Andrew.

I've owned and still use their full size low angle block plane for about 10 years. I personally prefer it's functionality & feel over the Lie-Neilsons. Both are, however, superb. :) It's my preferred tool for the initial stock removal when lowering an acoustic bridge. The ability to lock the lateral movement of the Veritas's blade seems to add a psychological assurance to the job.

Now, if their 'Apron Low Angle plane' had an adjustable mouth, it would be "perfect' for this kind of work. And without going 'fanboy', LV/Veritas tools, in my opinion, are still one of the best values in high end tools. I believe we may have some of the same tool dreams :)

I believe the one spec that is vital for a plane for bridge shaving is a low angle blade. That feature greatly reduces the possibility of tear-out.

The squirrel tail planes, unfortunately, are not available low angle models. They are, fortunately, customizable and extremely affordable for other lutherie tasks.

Good stuff :)

[Andrew]

Yeah I thought the same about the apron plane for this job. I might have thought a low angle blade would cause more tearout however, and perhaps not hold up long to ebony? But then I often tend toward higher cutting angles and a finer cut. Most literature agrees that higher angles = more work but less tearout. Thoughts? Perhaps ebony is different in some way. It sounds like you've planed more of it than I have.

Side note: I do most of my final thicknessing/truing of solidbodies with my Veritas LA jack plane :).

[Hesh Breakstone]

Except mine....  I don't agree with any blanket statement that shaving bridges is an OK practice regardless of who may be advocating it.

Sure it's been done for ages and sure even our shop does it too when appropriate for the instrument but a shaved bridge does not in and of itself get one a perfect neck angle.  Instead it's a quick-fix substitute for resetting the neck to the proper angle.

What happens when a bridge is shaved on a more valuable instrument instead of dealing the the improper neck angle with a reset is the instrument now has an original.... shaved.... bridge and as such when and if the instrument is properly restored to f*ctory specs the shaved bridge has to be removed and tossed and a new one installed.  This is trauma that the instrument did not have to go though had neck angle issues been dealt with with a reset.  And in terms of preserving value an original bridge would always be the preference if it can be preserved and has not split, etc.

Additionally, let's talk about Martin.  True Martin has various height bridges available but this was not intended to be a neck angle fix on older instruments only, the other heights were used on new instruments as well looking for another important spec.  The other important spec is between the D and G on the face of the bridge Martin is looking for a string height of 1/2".  Any less and the instrument will not be as responsive or as loud and any more and the rotational forces on the bridge start to creep up into the territory of possibly encouraging the bridge's trailing edge to lift as well.

Back tracking shaving bridges is fine when appropriate for the specific instrument but it is a practice that more and more these days is frowned upon when dealing with valuable or potentially one day valuable instruments.

Not trying to be argumentative but the notion that because others do it never meant squat to me personally.  In addition for those of us who do f*ctory warranty work we all also know and have experienced that f*ctories want to reduce the costs associated with liability and warranty repairs so the methods that they will cover or even advocate are not by any means an unbiased, we are MOST concerned with the well being of the instrument point of view.  Instead it's at times a quick, cheap fix, next.... and not necessarily the state of the art in conservation and restoration.

Here's another example - instrument comes in with loose bridge wings.  The f*ctory advises and only covers the coin to squirt some new glue under the wings, clamp, and call it good....  When a bridge is lifting the only way that I know for sure that I can guarantee my work and not in the same process have to guarantee the work done before me by the f*ctory is to remove the bridge, clean-up and expand the gluing foot print if expansion is available and it most always is and then reglue with say HHG and the appropriate concerns for using HHG.

So putting yourselves, ourselves in the shoes of mr and ms customer which way would you prefer your bridge to be repaired if this guitar was your baby?  Squirt some glue under the wings and call it good or careful removal, cleaning up the mating surfaces, expanding the mating surfaces if available to do, and then regluing with HHG using knowledge and experience for the handling of the glue?

So Tadej if you think that Mathew's statement above sets the record straight I beg to differ.

There was also a time in the trade when finger board extensions were routinely cut off at the body joint when reseting the neck.  Today folks look at this and consider it a crying shame.....

Anyway I have to get going I have a bridge to go shave....;)

[Andrew]

A noteworthy post. I also disagree with Larrivee's supposed statement that swelling of the back is the primary cause of a shift in neck angle. Sure, the back will change with time and humidity, but wood doesnt swell very much parallel to the grain, which is the orientation of the neck. So of course its worth knowing all you can about how the shape of the whole body is affecting the neck angle; the condition of the top, back and sides all come into play in some way. The example he gives just seems far too generalized for an operation that requires pretty specific consideration. Why not address said swelling if it was the cause? Etc etc..

[Mike Kolb]

carefully.... very carefully :)