bridge shave

GregMac

Member
Messages
27
I need to shave a bridge on a 12 string but i dont know how to measure it correctly so i dont remove too much material. I have shaved the saddle as far as possible already and the action measures 5/64" at the 12th fret. Any help with this would be greatly appreciated. Thanks in advance.
 

soulohio

Member
Messages
11,004
careful with that axe GregMac...
i got in a bit of a stickey wicket with a shaved saddle...just using sandpaper
 

guitararmy

Member
Messages
2,709
Unfortunately if the action is too high with the bridge sanded/shaved down, you might be in need of a neck reset....
 

202dy

Member
Messages
440
Basics:
  • A change of two at the bridge makes a change of one at the twelfth fret.
  • The bottom of the slot needs to be at least 3/32" to maintain stiffness over the top. An eighth would be better.
  • Most of the time shaving the bridge is treating the symptom rather than the disease.
The reason most people shave a bridge is to avoid:
  • Repairing loose braces.
  • Replacing the bridge plate.
  • Re-setting the neck.
If the top has a high dome, the answer is most likely braces, bridge plate, or a combination of the two. If that is not the problem it is likely that the geometry is wrong. The reasons could be that the neck is coming loose from the block, the neck is in rotation, or the guitar was not right when it was built. Evidence of rotation can be seen as a dip in the top at the north end of the sound hole through mid top.

Since these three services are expensive, it makes sense to shave the bridge on an inexpensive, or sometimes mid level, guitar. If the instrument is well built, shaving the bridge is probably the last thing to do. If at all.
 

RustyAxe

Member
Messages
3,012
First, find out WHY the action is too high. Then price out what the guitar needs done. Personally I'd never shave the bridge. If the neck needs a reset, it won't get any better on its own, and when its finally done right, you'll need a new bridge or a too tall saddle.
 

John Coloccia

Cold Supporting Member
Messages
9,578
I need to shave a bridge on a 12 string but i dont know how to measure it correctly so i dont remove too much material. I have shaved the saddle as far as possible already and the action measures 5/64" at the 12th fret. Any help with this would be greatly appreciated. Thanks in advance.
GENERALLY SPEAKING, if you straighten the neck and lay a straight edge across the frets to the bridge, you normally like to see the bottom of the straight edge just barely clearing the bridge, or really close to clearing at any rate. That will normally get you a saddle that is about 1/8" tall. That's kind of the ideal situation you look for...generally speaking.

But there are just too many variables to diagnose something like this without having the guitar in front of me. That's my opinion, anyhow. I'm all for people learning setup work on their own, but for something like this it really pays to have a trained eye and some experience to take a close look at what's going on and make some recommendation as to what can be done to fix it.
 

icr

Member
Messages
2,849
I need to shave a bridge on a 12 string but i dont know how to measure it correctly so i dont remove too much material. I have shaved the saddle as far as possible already and the action measures 5/64" at the 12th fret. Any help with this would be greatly appreciated. Thanks in advance.
You need to double the distance at the 12 fret. So if you need 1mm less height at the 12th fret, you need to shave 2mm from the bridge and saddle. The million dollar question is 'what is the minimum break-angle over the saddle to prevent buzzing.'
 

GregMac

Member
Messages
27
Thanks for all the advise. I used the straight edge along the fretboard to get my height to shave to and resessed the pins by 1/32". That helped when it came to intonating it. Sorry for posting in the wrong place.
 

walterw

Platinum Supporting Member
Messages
38,257
I used the straight edge along the fretboard to get my height to shave to
OK, but how much did you have to shave away?

too much and you get a bunch of other problems:

a too-thin bridge loses structural rigidity, allowing for more top warping

too shallow a saddle slot leads to problems seating the saddle

too shallow and the strings poke out too far, allowing the reinforcing wrap to sit up on the saddle
 

GregMac

Member
Messages
27
I routed the top of the whole bridge by 1/32" including where the pins sit. Also i redrilled the top of the pin holes by 1/64" to return the little rebates that hold the lip under the pin head as the routing had removed them. Its playing fine. Its only a crappy few hundred dollar guitar i picked up so i could practice setting up 12 strings. I have a worse problem now with a telecaster that needs a half turn on the truss rod to get more relief but the nut is coming loose way too soon. Any tips or suggestions would help. Its a screw head accessed through the heel. It seems like it will screw out completley although it tightens up fine.
 




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