Tools/Methods for Bridge Making/Alteration

Jehu · December 2014

I now feel a sense of commitment to this thread, but let me add a disclaimer. I know that there are some real-life luthiers on this forum, so any and all corrections are accepted and welcome.

If I were to make a new bridge, I would rough it out and do the above, and sand down and radius the top to the desired action. Then I would:
1) Clip off some pieces of paper clip.
2) Slip said pieces under each string and against the now broad surface of what will eventually be your saddle. Adjust each piece to set your intonation. It will be a bit off due to the height of the clip piece, but it will be very close. (And will give the relative lengths of each string. The absolute position can easily be adjusted later.)
3) Score the saddle at the front of those clip positions. File the bridge back to that mark, then file the back end forward leaving yourself a decent (2mm-ish) saddle.

Now you want to make sure your string spacing is good. The key to not being a hack is to make the distance between the outsides of the strings is equal (rather than the distance between the centre of each string). Remember in high school when you thought, "when the fuck am I ever going to need this"? Well.

You want the outsides of your 1st and 6th strings to be about 4mm from the outside of the fretboard at the highest fret. Once you have those in position, measure the distance between the insides of those strings, at the bridge. Divide that by 5. Now you have the distance between the outside string and the adjacent string centre. You need to subtract half of the width of that (next) string gauge to find the notch. (Say what?) Repeat for all strings.

As for notching the bridge, I like Jazzaferri's idea as a lo-fi solution. I use 2 or 3 passes with the appropriate nut file, which takes about the same amount of time as turning my head to locate the Dremel. But then I'm irrationally biased against electricity.

Buco · December 2014

Hey was sweet @Jehu especially the part on using paper clip to find the intonation.

Something I read here about sanding the feet of the bridge and that I found worked better for me is to use making the angel in the snow motion of your arms when fitting the bridge instead of going straight back and forth.
When I went back and forth, as careful as I tried to do it it still rocked forward and back and made a slight U on the bottom of the bridge. When using that diagonal movement, what arms do with angel in the snow, it was foolproof.

rgrice · December 2014

Excellent @jehu! Thanks so much! I think we'd all love to see steps of your bridge building! I'd love to try to do so but have no idea how to begin.

Steveareno · December 2014

Nice looking bridge! I like my action on the high side, so have shimmed my stock Dell Arte bridge using a couple of Popsicle, or ice cream sticks...cut to size and tinted. They're hardly noticible. You can color them with a Wood Finish Stain Marker, or even a brown Sharpie. A pack of ten or twent is only dollar or two and they cut and trim easy. Apparently they're made of maple. Funny, I've seen top players use everything from guitar picks to Metro tickets (Django) and matchbook covers. Kinda cool, but I prefer wood on wood.
Swang on,

Jazzaferri · December 2014

Perhaps being older and a little more patient :laugh: I use 150 grit to do the job.....takes longer but leaves a nice finish on the bottom.

I confess to roughing in slots in a bridge using my table saw. Lock bridge in place, figure out how many turns of the wheel to raise the saw to the right depth of cut.

HIGHLY NOT RECOMMENDED FOR ANYONE

Jeff Moore · January 2015

That's a nice set of instructions.
You didn't mention shimming to raise the bridge back up? Seasonal weather moves the bridge up and down (even though I'm controlling humidity as best I can) so shims seem like a necessary and convenient part of keeping the action where you want it. I'm sure you already know this.
I'm in Minnesota with warm air heating, so it's perhaps a tougher place for guitars than average.

AndrewUlle · January 2015

That's why I just bought a 14 gallon-per-day humidifier. I'm keeping it at 35% - think that's enough?

pickitjohn · January 2015

@Andrew Ulle
40% to 50% is optimal. I like to maintain 45% myself

Jeff Moore · January 2015

Seating the bridge.
Buco, yeah I described as the figure 8 or bow tie motion (I like angels best). I found I couldn't help but rock the bridge while sanding against the paper taped to the guitar top if I just moved back and forth. If I used the snow angel motion, the tendency to rock was abolished by the counter motion of left and right hand. Each trying to rock in the opposite way. Hence, flat bridge seats and less need to concentrate on the impossible.

The other thing I couldn't live without is a way to clamp the bridge. I made simple "clamps". One to hold a bridge upside down for hollowing the inside, the other for shaping the outside of the bridge. I'm always using electricity for this stuff, so my clamps are things I'm holding in my hand as I press the bridge into stationary tools. If I was using chisels, I'd want a heavier table clamp (clamps) to really stabilize the bridge upside up and upside down, so I could use both hands to work.
One rational for using stationary tools is that there's less stress on the bridge than using hand tools. There's no impacts or energy focused on a tiny spot, like a chisel used to thin the already thin faces of the bridge when hollowing it out and a vise using enough jaw pressure to withstand chiseling. A hand held blade is pretty focused energy, but obviously has been done beautifully for a few years long than I've been alive. Cheaper up front too. I'd really want a wooden jawed vice (rather than metal) for a bridge, if I was working with hand tools. Even then, if your thinning out the interior of a bridge to a high degree, the resulting bridge is not threatened with dremels and stationary stuff. There's not much focused energy, but bigger need for investment and space.

A long time ago, it became apparent that having a near perfect set up was a matter of money or learning, and a near perfect set up was necessary for a guitar to sound really good and play easy. Worst is, set up seems to be bi-annual at most and annual at least.
Besides a few years of slight fortune, I could never afford a guitar techs. So I parlayed my house carpenter skills, tools, and techniques into bridge and neck-fret carpentering. I also quit worrying about aesthetics. My bridges and frets work good, but look kinda messy.

Jehu · February 2015

Well I haven't got around to replacing that bridge yet, but I was recently working on a bridge for an archtop I'm building so I thought I'd add some images to demonstrate what I was blathering about above.

Jehu wrote: »

If I were to make a new bridge, I would rough it out and do the above, and sand down and radius the top to the desired action.

Here we are roughed out. To get to this point I just used a tenon saw, a rasp, and some sandpaper. (And possibly a small plane, but I'm a sucker for planes.)

You can see where I pencilled the amount of wood that needs to come off to lower the action to where I want it, which in the case of an adjustable bridge is on the very low end. To determine this, stick the bridge in and measure the 12th fret height of each string. However much you want to lower the action, you will need to take off twice as much material from the bridge. Probably also a good idea to check your nut action before going through this song and dance.

Then I would:
1) Clip off some pieces of paper clip.
2) Slip said pieces under each string and against the now broad surface of what will eventually be your saddle. Adjust each piece to set your intonation. It will be a bit off due to the height of the clip piece, but it will be very close. (And will give the relative lengths of each string. The absolute position can easily be adjusted later.)

This will most likely look something like this: