Official Luthiers Forum!

It's cool to see the different approaches, especially the range from simple to complex. Thanks everyone for the great ideas!

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Steve Smith
"Music is what feelings sound like"

I copied Tony Karol's

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It's not what you don't know that hurts you, it's what you do know that's wrong.

made from scraps of delrin, some dowel pins, and a bolt & washer. i put it in my milling machine and cut the slot. it's a little short because it was made from scrap material though and only really useful for pyramid bridges. but it was super simple and very fast to make.

This one is really helpful, because mine won't easily accept a pyramid bridge! Thanks!

I sold my milling machine so that's why I'm looking at other jigs.

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Steve Smith
"Music is what feelings sound like"

If you happen to knock together something like mine, it's useful for all manner of bridges, pyramid, belly, concave or whatever. It's fast and easy to make, and is super cheap, requiring no special knowledge or equipment (or a Grainger account) but it doesn't hold the router firmly in the path the way the ones that have a guide on both sides or the rail systems do 'cuz that's my job with this one, but that's not a problem for me. I don't mind doing it.
I either slot the slot and then lay out the pin holes,or lay out the pinholes for an existing guitar to index the slot.
It works pretty much with any router or laminate trimmer with an edge guide.
Just be sure your edge guide is STURDY.
You also need to be aware that you are holding the router against the rail piece and so you need to be careful when plunging and routing, mainly plunging, as long as you route from left to right.
I use a 1/8th inch double fluted carbide router bit with a 1/4 inch shank, and cut the slot slowly in one pass.

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Old growth, shmold growth!

fwiw, in any well though out fixture design, you need to restrain movement in X, Y, Z and a, b, c axes. lock those down and you'll have a fixture that is repeatable every part, and requires no fussing to make it work. -not including wear of course (another discussion) if you look at the pin and clamp design, every axis of movement is accounted for, and every face of necessary registry is accounted for. aside from using a conformal nest, which have their own issues, these feature can be applied to many, many, other operations in the shop.

Right. Hand pressure can work for some of that.

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Old growth, shmold growth!

Interesting. I do repair work for a living and haven't had time to pop off down to to Grainger to get the necessary parts for something more complex, LOL!

After my practice saddle I don't think I've been anywhere near blowing a slot.

You do something enough times and the equipment becomes almost secondary...

Here's a bridge I made for a guitar that recieved a Maton pickup.

The saddle slot is perfectly straight, landed exactly where I wanted it to, and the saddle fit perfectly in the slot. Took about ten minutes total to make the whole bridge from a blank.

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Old growth, shmold growth!

My only point is that it's nice to have cool equipment, but it's also nice to be able to achieve the same results on a budget, or in the middle of the night when all you have is plywood laying around your shop and you cobble something together on the fly.

I'm a night owl. Sometimes I work from 8PM to 4AM.

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Old growth, shmold growth!

Actually I like your mill, and David Collin's as well! Anything with a laser....

I think consistency comes with experience, but I get where you come from, as you've explained before that anytime you can eliminate the possibility of human error in order to yield the most consistent result, you'll take it.

I haven't found consistency in fabrication to be a problem though.

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Old growth, shmold growth!

Todd,

I like your 2-d version.
Do you have a picture of your mill mounted on a guitar for routing the bridge that is on a guitar?

For bridges in place on a guitar when routing:

How do you adjust the slope horizontally across the bridge? Do you use shims, or is there an adjustment I'm not seeing in the pictures. Do you cut the bottom of the slot parallel to the bottom of the bridge or parallel to the slope of the bridge so that the exit of the slot is the same on the bass and treble sides of the bridge?

How do you adjust the vertical slant of the slot relative to the bridge. Some vintage guitars have a bridge that is leaning forward slightly due to belly behind the bridge. Do you use the plane of the strings as the index for the slot or the top of the guitar, or the bridge? Again, do you use shims or am I missing something in the pictures? Even on new guitars I slant my saddle backward just a few degrees to counteract the string tension.

How would it work if I used horizontal linear rails like yours, and a plunge router mounted to take care of the vertical movement?

Let's all Jones together for one like David Collins has.

James

Add me to the list of people with Todd Stock jig envy. Until he starts selling them, I use my binding channel jig and it works pretty well for me. It's basically the same as the StewMac TrueChannel jig. I put a fence on it and a threaded bolt as a depth stop. Then I clamp the bridge to a sled and slide it against the fence with stop blocks clamped on both ends. It is dependent on my holding the sled snug to the fence but a final pass with tape on the fence cleans up any variation. Can't do bridges on guitars. No pictures handy, but I can take some if there is demand.

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Mike Lindstrom

As much as I like Todd's jig (not to mention David Collins' unit) I'll be making mine out of birch ply and maybe some lexan (for now).

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Steve Smith
"Music is what feelings sound like"

for an "ultimate" slotting jig look in the archives for the Collins version! most impressive!

No need to look in the archives, it is in this thread.

I need to make one, too!

For my first guitar, I just drilled a series of holes and cut the slot with a chisel.
For the second, I held the bridge blank in a Workmate with a couple of guides clamped onto it for the router. High tech, hey?

Wish I had a drill press.

Oh, I can absolutely see the need for one! I'll definitely be aiming for something like yours when I feel that need. Right now, I'm trying not to get too jigged up. I want to build free form and with minimal jigs and power tools for a while.

Todd, thanks for posting that. I see that you have travel in the X and Z directions. Do you have any adjustment in the Y direction or is that determined solely by clamping the base in the proper position? I suppose a simple positioning jig could be made from a piece of wood, acrylic or other material.

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Steve Smith
"Music is what feelings sound like"

All I do is mark the center line, slap it in, adjust the depth, and route.

One trick pony though.

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Old growth, shmold growth!

Thanks for the pictures and the info, Todd.

James

You don't really need a drill press. You can laminate (epoxy) two cheap back saws together, maybe with a spacer of standard wood veneer (whatever gives you the correct kerf). You have to remove the saw plates from the brass/steel backs. laminate the saw plates together, open up the slot in the brass back and epoxy the new blade into the back. You have a dedicated saw for cutting bridge slots.
All you really need then is a bit of wood to act as a guide, maybe some sort of depth stop. I used this technique for Classical bridge slots. Low tech and simple. With a SS Bridge slot you might want to fill in the ends - so that the slot isn't open ended.