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Hello luthiers,

I know this topic has been discussed many times but I screwed this up on my last build and I want to make sure I get it right this time. So I'm trying to figure out what should be the optimal clearance above the saddle slot. Right now I have 3/64 inches (1.2 mm).

Thanks
Dominic

For me, I like my unfretted board to be coplanar with the top of the bridge. So my value for how much gap as shown in your photo after fretting would be however high my frets are which sometimes differs. 1.2mm sounds about right or reasonable, and some people like to have even a bit more backset to accommodate the top pulling up under string tension.

So IMO I think you’re good but let’s hear what some other folks have to say…

Nice clean work!

What's the height of the bridge?

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

The bridge is 11/32 inches/8.7 mm high.

I ignore the bridge height and go by how high I want the strings above the surface of the soundboard (since that's what determines torque on the bridge). Fret plane projection 2-2.5mm below the target string height. That accounts for about 0.8mm (1/32") pull-up under tension.

So your current projection of 9.9mm should give around 12mm string height, with a little over 1/8" saddle stick-up. Personally I'd aim another half millimeter higher, but it's fine as-is.

You need to know how much your neck attachment system moves under tension and settles after 8-12 months. If quite a bit you’ll need more initial clearance over the bridge.

You can duplicate string tension to some degree by supporting the headstock and adding about 12 lbs of weight to the upper bout. I like the straightedge to clear the bridge by a 32nd or so under tension on my guitars.

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