How To Install Tune-O-Matic Bridge Posts

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Important: Before starting to install the tune-o-matic bridge posts (or bushings) make sure the neck and fingerboard are in their final positions. The position of the bridge on the body is highly dependent on the fingerboard and the nut. Since the strings vibrate between the nut and the bridge (the scale length) and since the position of the nut is fixed, the exact position of the bridge will determine the correct scale length.

Step 1: Alignment. Place a long ruler along the side of the fingerboard and extend the ruler onto the guitar body. Then draw a line on the body. Do the same on the other side. You should end up with two lines that are extensions of the fingerboard (see image). The two lines should not be parallel to each other since the fingerboard is tapered.

(Note that in this case the body has not been finish-sanded yet so I’m not worried about pencil marks. If your guitar body is sanded to receive its varnish, then I suggest placing making tape on the body and drawing the lines on the tape.)

draw-two-lines-parallel-to-the-fingerboard
Draw two lines that extend from the fingerboard (line was made bolder in Photoshop)

The two lines extending from the fingerboard
The two lines extending from the fingerboard (lines were bolded in Photoshop)

 

Step 2: Find the bridge positions. By knowing the scale length, you can determine the exact location of the bridge saddles. Place a long ruler on the fingerboard aligned with the center axis. The scale length of this guitar is 25″, so the 25″ mark is placed at the location of the strings over the eventual nut.

Place a ruler on the fingerboard
Place a ruler on the fingerboard

A scale length of 25″ means that the 12th fret will be at 12.5″ from the nut and 12.5″ from the bridge, meaning the half-way point.

Check the scale length at the 12th fret
Check the distance at the 12th fret. It should be half of the scale length

The exact position of the bridge saddles can now be located. Before placing the bridge under the ruler and in order to allow for intonation compensation (later during tuning), bring all the saddles at their most forward positions (as shown in the image below) and align them under the ruler.

The bridge must also be aligned between the two fingerboard lines; you can easily do this by eye, or else use a ruler. Once the bridge is aligned for scale length and between the fingerboard lines, then mark the locations of the bridge posts using a pencil.

Identification of the exact location of the saddles on the bridge
Identification of the exact location of the saddles according to scale length

On some bridge models, there may not be enough “saddle-room” for correct intonation at the bass-end of the bridge. In that case, it is common practice to shift the bass-end of the bridge a few mm away from the pickups. You can do this by rotating the bridge by 3 degrees around the treble post (see the green line in next figure). This is optional but popular.

mark-the-positions-of-the-bridge-posts-2
Mark the positions of the posts (lines and circles bolded in Photoshop)
mark-the-positions-of-the-bridge-posts-closeup
Close up view of post positions 

 

Step 3: Drill the holes. Before starting to drill any holes, determine the depth of the holes. Use one of the bridge posts to estimate the depth and place masking tape to identify the depth. Hint: it’s better to drill a slightly deeper hole rather than a slightly shallower hole.

Mark the depth of the hole on the drill bit with tape
Mark the depth of the hole on the drill bit with tape

Before drilling, make sure the body is extremely-well clamped-down and will not move during drilling. A drilling mistake at this stage of the build can be disastrous for the guitar body and the guitar builder’s mind!

Drill the bridge post holes
Drill the bridge post holes

 

Step 4: Verify. At this stage it is wise to check the depth of the holes and also the final alignment.

Check the depth
Check the depth
Compare the depth of bridge post holes with posts
Compare the depth of bridge post holes with posts

 

Final alignment verification… everything fits well. Do not install the posts yet if the body is not ready for assembly because removing the posts will be nearly impossible and will damage the holes.

Check the fit of the bridge onto the posts
Check the fit of the bridge onto the posts

 

The tailpiece is usually 2″ behind the bridge. In this case, I drill the ferrule holes.

The ferrule holes are drilled
The ferrule holes are drilled

 

I would love to hear your comments, ideas and suggestion. Leave a comment below.

About araz

I'm an ex research scientist, now building electric guitars :)

26 thoughts on “How To Install Tune-O-Matic Bridge Posts

  1. Hello. I found you doing a google search on locating a bridge on an electric guitar.. I’m putting together a kit soon, but I think I’ll actually build an electric short scale, or shorter than normal scale electric guitar in the future out of wood from Indiana. My brother has a bunch of Walnut / black walnut for bodies and a bunch of birdseye maple for necks.. as well as a wood shop.. So, I’m going to try my hand at building a very simple short scale (23″ or 24″) single cutaway guitar with 22 frets.. Medium tall, etc,.. Thanks so much for this info on the locating the bridge. I have the Melvin Hiscock book on building guitars and it helped a lot, but this is a better way of finding where the bridge should be. Does this work on a Fender hard tail bridge as well ?

    1. Hi Tim,

      I think starting with a kit guitar project is a great idea, it will get your feet wet…

      A few things about building from scratch:

      1. When you say “short scale” I assume you mean “short scale length”… Unless you know how to calculate fret distances and properly cut fret slots in a fingerboard, I recommend to go with standard electric guitar scale lengths and buy a pre-slotted fingerboard. The big manufacturers have standard scale lengths of 24.75″ for Gibsons, 25″ for PRS and 25.5″ for Fenders (see a great description of scale lengths here http://www.stewmac.com/freeinfo/Fretting/a-scalelength.html ) You can create a guitar with a different scale length for sure, but it also means a lot of work.

      2. The Melvin Hiscock book is good but I don’t necessarily think it’s very practical for finding information in an easy manner… It’s written too much like a novel with no separation of subjects… The book that I highly recommend is Building Electric Guitars by Martin Koch. It’s highly detailed, easy to read, many diagrams and more of a step-by-step approach.

      3. The approach outlined in this article should work for finding the bridge position on any guitar. Just make the necessary modifications for the specific hardware of a Fender bridge type.

  2. I have a Gibson les paul double cut away with the whip stop bar tailpiece. What I would like to do is add the tuno’matic bridge. I think the holes that are there will work for the bridge but I would need to drill holes for the stop bar tailpiece. Is that possible?

  3. Lots of help thank you! Great pictures too. Perhaps it would be nice to also show the location of the stop tailpiece to finish the job?
    Many thanks

    1. Hi Andy,

      As requested, I just updated the post to include the tail piece holes. However, on this guitar I have chosen to install ferrules… see last image in article.

      Take care,

      Araz

  4. Thank You very well explained instructions, I will start on a Les Paul project soon, I bought a body and neck already glued from guitarfetish.com buy out clearance sale, but the body doesn’t has the holes drilled for the bridge nor for the stop tail piece, how far has to be the stop tail piece from the tune o matic bridge? Or maybe I can just use a wrap around bridge too

  5. Hi, just curious as you don’t say in the post…
    the line you’ve drawn that represents where the bridge sits, is that exactly 25.5″ (or whatever scale length) from the edge of the nut?
    I’m wondering if you have added any “compensation” other that the 3 degrees for the bass side? I keep hearing about people adding compensation but I’m never sure if it is to both sides + the extra on bass OR just the bass side.

    Cheers!

    1. Hi Annalise,
      Yes, the line is drawn exactly at the scale length from the nut.

      1. Before finding the final position of the bridge, bring all the saddles on the bridge to their most upfront position (meaning, turn the little screws until the saddles are closest towards the fingerboard).

      2. Then place the *saddles* on the line.

      3. Mark the two post locations with a pencil and remove the bridge.

      4. Calculate the 3 degrees and place a new pencil mark for the new bass-side bridge post location.

      That’s the final position for the bridge.

      When you put the strings on, you will have ample space to move the saddles for intonation compensation…

      Hope this helps,

      Araz

  6. Hello there and I’m confused whereby in step 1 it says “The two lines should not be parallel to each other …..” , yet the photo for that step says “Draw two lines parallel to the fingerboard” – please advise, thanks.

    1. Hi Hugh,

      I can see how that wording can lead to confusion.

      The two lines are parallel to the fingerboard but not parallel to each other. That’s because the width of the fingerboard is smaller on the nut side and wider on the body side. So the lines will get progressively further from each other.

      I changed the description on the image to remove the confusion.

      Araz

  7. Hi

    I caught this article just in the nick of time before drilling these holes for the posts. Whew ! Only after reading this did I see all the dangers involved. I will read it again and again before drilling.
    Thank you – the best guide on the net.

  8. Hello, so all scales are a minimum? Like 25.503″-25.579″ for example. And are shortest on the treble side? I have a schaller that has an angle built in. If I make the 1st string@ scale then no other string can be. Is this correct?
    Thanks.

  9. Hi very nice and clear description, one of the best on the net.
    But i have to make you question for a GTB series bridges by Wilkinson, and it’s adjustable G and B Saddle,.
    Should I drill posts like in your description with 3 degree angled or should I drill them straight and parallel to pick up cavities? That’s my doubt Hamlet! . I’m building a Prs style guitar. And any advice in bridge change? i heard that is better the on with individual saddle adjustment! Thanks in advance! Hope you anser soon. I would to spray my guitar!! Have a nice evening!

    1. The type of bridge you mention requires the two outer E strings to be correctly positioned first, and then the inner strings will be more or less correctly placed and you can fine tune them with the adjustable saddles.

      So the question is, how to get the correct placement of the bridge posts so that the two outer E strings are placed correctly?

      1) You need to simulate the finished guitar by putting on the tuners, the nut, and then placing the bridge at about the right location on the body (place a shim under the bridge to mimic the bridge post studs). No drilling at this point, just place it on the body.
      2) Then insert the two outer strings from the tuners, over the nut and over the bridge. You will need to figure out a way to hold the strings in place in order to tune them to correct pitch (see this video for an idea https://youtu.be/-QXLfAIHjnI…).

      3) Now, move the bridge by hand until the outer E strings are correctly tuned… that’s your final bridge post locations.

      I hope what I said makes sense to you. The video link is a great help. The main issue I can foresee though, is how to keep the strings stretched on your particular bridge type. One idea I have is to clamp a piece of wood on a bench, hammer in, partially, two nails and hook the strings on them and then over the bridge saddles, over the nut and into the tuners.

  10. You mention that you should “bring all the saddles at their most forward positions” and place them at the proper location (centered on the scale length). I have found other sources that say to set the saddles in their center position before placing the bridge. With your method there can be no intonation adjustment to a slightly shorter scale length — is this okay? I believe your method is correct because all intonation adjustments have to compensate for a string thickness of greater than zero which means that all intonation adjustment has to be “scale length plus some adjustment” and never “scale length minus some adjustment”. Is this correct? I’m just looking for some clarification since I have found many other sources that suggest setting saddles at the center of their adjustment point.

  11. Hi!

    Thank you so much for the info! I have a question about bridge placement and neck angle. In the article, you mention that the neck has to be in the final position before starting the bridge locating process. My question is, how do you know what neck angle to create before the bridge is installed? Doesn’t the neck angle differ with the type of bridge you decide to use? What if you have to raise or lower the bridge? Wouldn’t that affect the correct neck angle? I’ve seen info online with varying degrees of neck angle, from 2 degrees up to 7 degrees or more. Is there a standard neck angle number when using a certain type of bridge? If not, how do you calculate the neck angle to use if you may have to adjust bridge height later in the build?

    Thank you so much!

  12. Hello I am building my first guitar and I plan on a neck thru 25.5 scale with a tune o matic bridge .I was just wondering what neck angle would be good to use.

    1. Hi Kevin,

      The neck angle is mainly determined by the height of the bridge above the surface with respect to the height of the fretboard. The best way to determine the correct neck angle is to draw a full scale side-view plan of the guitar. Draw the body, the tune-o-matic bridge, the neck, the fretboard and even the heights of the frets… then you’ll know what neck angle needs to be.

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