Bridge-Pin Science

by John Mickelson

What role do bridge pins play in sound? Aren't they just to keep the strings from flying off? I mean Ovations don't even have bridge pins do they?

I've been fortunate in having being able to talk in depth with well over a hundred experienced luthiers over the past few years. These individuals have contributed a large mass of empirical data about how the fit, shape and weight of the guitar's various parts relates to the efficiency with which their instruments make sound, and they've shared their knowledge freely with me.

The last components installed on any guitar THAT DOES USE BRIDGE PINS are the bridge pins. Okay we can split hairs and say that the string is because you have to put it through the machine heads (God, am I glad to get that cleared up finally).

So... here's the deal. There is your soundboard with the bridge and beautiful hard saddle and inside your guitar is the quarter sawn maple bridge plate correctly glued under the X brace. The saddle and action are all appropriately set. (See Roger Simonoff's article on bridge movement as well as Dan Erliwine's excellent book "The Guitar Players Repair Guide)
When all is right in guitar heaven the guitar's pins need to contact four things all at once to achieve their highest coupling effect. The string, the top, the bridge and the reinforcing plate (bridge plate). 1,2,3,4. The pin itself would make the fifth.

FIK brand bridge pins have been engineered deliberately to allow you to modify the tone (volume, sustain, fullness) of your guitar's voice. The beauty is a bonus!

How does that work?

The taper of FIK brand pins is such that when the bridge is ever so slightly reamed (see instructions) the hole and pin have the identical taper. Once that is done, on those guitars that require it, the string slot (most custom guitars have half the strings diameter worth of a Groove milled into the bridge) is deepened to accommodate the string.


The original holes on some commercial guitars are a straight hole or a different taper than the pins employed. The pins are plastic or Ebony and have a groove milled into them to accommodate the string. Rather than occupying the hole uniformly what actually happens is the string wobbles in the hole or tilts forward as the string ball levers the bottom forward. The inside of the guitar where the string ball rests against the reinforcing plate is more than 50% air and the string ball gets cocked awkwardly in the groove.

HMMMM!!!!! So now we have the string held in by the ball end and the pin kind of insures that string isn't going to pop out but the coupling of the pin, string, bridge, top and bridge plate is only sloppily done at best. Check me out. Next chance you get look up your guitars insides with a mirror and flashlight and you will see a gap between pin and other components.

John Gilbert, a classical guitar maker weighs every single component of his guitars' tops. All the fan braces weigh exactly the same amount. All his bridges weigh exactly the same. All of his instruments are beautiful sounding. You don't need to play twenty to find a good one. All are great.

So, without all the esoteric stuff what can you expect from any given pin?

As your guitar's top gets warmed up the bridge begins tilting forward and backward just Rocking Out BABY, YEAH!! (Sorry Stones are doing "Satisfaction" in the background) the guitar top becomes a diaphragm pump. That top is throbbing. An optimum amount of mass is crucial to this flywheel effect thus to optimum tone. By offering pins in different materials that are uniform in style you can optimize the tone of your guitar to your tastes.

I have one customer who has several identically sized sets of pins of different materials that depending on the situation he trades out. When he is recording he seems to like a variety of pins all at once in his guitar. When he performs he dresses that D-18 to Kill.

For long sustain and all around full tone, I would recommend Ivory pins every time.

If I had a guitar that was lightly braced and really like the warm mellow muddy tone of it I would probably go with Water Buffalo. If I need real snap just punch and maybe a little brassiness I use the Bone.

When would you not use Slotted Pins??

I am a huge advocate of unslotted pins and getting the most of the string captured in the bridge. I have just seen to many guitars improve this way.

BUT! There are instances where the geometry of the guitar precludes this. In fact I occasion to rethink the whole concept. My first reaction to new information was to take it as fact.

I asked two engineer friends to review my notes, test my theory(s) and give me some solid engineering feed back. One happens to be one of the finest Luthiers on this Continent. The other is a fantastic guitar player and brave enough to modify all of his guitars to be able to provide an honest opinion. I supplied each with several sets of pins in different materials.

Engineer One supported the slotting the pins. It did not all come down to point to point contact theory based on spheres. If the String, the Pin and the other contact points were all titanium or stainless steel then the transfer of energy from string to Pin to Top would be best achieved with a slightly slotted pin and slightly slotted bridge. For practical reasons over the life of the guitar this engineer's position is that the pins are easier to replace than a worn out bridge or bridge plate. I can't argue with that.

Engineer Two said " In real life??" The string compresses, the woods involved will compress and the bridge pins themselves have a certain give in them so that still, with the exception of those guitars where a string slot will compromise the geometry of string break angle over the bridge or the integrity of the guitar, I have to advocate deepening the string slot." Once the string is secure it should not move enough to ever wear anything. It is that lack of positive contact that induces movement of the string winding so that it would eventually saw out the slot!"

Want me to take a position? Slot your bridge you won't be sorry. If you are unsure take it to a pro have him read this or have him/her call me.

There are some damn nice guitars out there with funky pins, plastic saddles and worn out nuts. Ballpoint pen covers or chunks of wood crudely fashioned to hold the strings in place. They are fantastic sounding, lots of them. They probably would be just that much nicer with a little respectful attention.

What about nuts and saddles?

I occasionally have material big enough for saddles or string nuts. Even though I am in the business of making and selling Ivory Products primarily I discourage saddles of Ivory. How come John? Geez?

Saddles typically are very thin. Fossil Walrus Ivory has almost an "impossible to account for" tendency to warp. And it is pretty strong stuff. So if you make a nice saddle and it warps in the vertical direction you will lose contact with the bottom of the saddle slot as well as raise your action mess up intonation etc. If it warps front to back and you have a very deep saddle slot that is very close to the front of the bridge it might actually crack the front of the bridge off!!!

So I really like Bone nuts and saddles. I have some of the best stock you will find anywhere. I have a proprietary process of tempering this bone so it actually looks aged and seems to be somewhat harder than the Ivory. In fact bone is heavier than Walrus Ivory.

So I only sell nuts and saddles to dealers or builders. It eliminates problems for you and for me. You can rely on this. If you get a saddle blank from my shop it was stabilized for a minimum of one year and treated properly will not warp. Again I only sell saddle blanks to qualified technicians.

How about those wild colors? Where can I get a set of those Pins like I saw?

The grade of Ivory seems to change every time I restock! This meant I was not able to really offer any predictable categories. That has recently changed. I now offer:
  • Select Cream to light tan with nice highlights
  • Premium Select Richer darker Yellows, Golds, Tans, Lighter Orange with Lots of Color
  • Deluxe Deep Orange, Great Shades of Brown, Green, Dark Brown
  • Custom: This is anything that I am asked to take the time to create that is different or special. It might end up being just like the Standards someone else has from me but it took extra time and special effort to make them your way so they are custom. Typically this really means a request to be on the list for some of the wildest Ivory I ever get.

Thanks for letting me share this with those of you who are interested. I am sincerely interested in your ideas or questions. If your questions are of a personal or business nature lets confine them to personal e-mail. If we can contribute to the musical community at large through this dialogue I am willing to participate in an open discussion for all.

John Mickelson can be contacted here. You can visit his website here.