How deep to rout a neck pocket?

[Wasted4440]

Hi everyone,
My build is getting close to the point where I'm ready to rout the neck pocket, and I just wanted to double check that I have the notion of how to calculate it all figured out.

I'm using a Gotoh standard bass bridge and pre-radiused fretboard from Stewmac, as well as some of their high/wide fretwire. As was suggested to me earlier on the forums, I should measure the height from my body surface to the bottom of the saddle when the adjustment screws are completely lowered. So essentially I want to have the height of the fretwire crown/fretboard/neck proud of the body surface to equal that height?
-Should I do the measurement using the center of the radiused fretboard (7/32") or the side (5/32")?
-Does it matter if I make the measurement based on the low E string vs the A, D, or G strings?
-Would it make sense to make the saddle height measurement with the adjustment screws lowered slightly (maybe about 1/32") to give myself some leeway?

Here's a MS paint picture of what I think it should look like if I'm understanding how to the do the measurement correctly. My calculations are telling to rout just a hair shy of 5/8" by this method.

Thank you for you replies!

 

[Bruce Johnson]

Yes, you are looking at all the right things. However, the dimensional stackup that you are showing in your Side View should be the state at the edges of the fingerboard; that is, under the E and G strings. Those are the two saddles that should be approximately sitting on the metal, when the bottom of the string is resting on the fret. Because the center of the fingerboard is higher, by 2/32", the A and D saddles will end up raised up off the bridge plate by about 2/32" with those strings sitting on the frets.

Also, you need to include the thickness of the bridge's base plate in your calculation. It's probably around 0.090", but you need to measure it.

From those numbers, I see your depth of neck pocket to be:

0.750" (neck thickness) + 0.156" (5/32", fingerboard thickness at E & G) + 0.050" (fretwire height)
- 0.406" (saddle height) - 0.090" (thickness of the bridge base plate).​

That comes out to a neck pocket depth of 0.460" or about 15/32".

 

[Wasted4440]

Yes, you are looking at all the right things. However, the dimensional stackup that you are showing in your Side View should be the state at the edges of the fingerboard; that is, under the E and G strings. Those are the two saddles that should be approximately sitting on the metal, when the bottom of the string is resting on the fret. Because the center of the fingerboard is higher, by 2/32", the A and D saddles will end up raised up off the bridge plate by about 2/32" with those strings sitting on the frets.

Also, you need to include the thickness of the bridge's base plate in your calculation. It's probably around 0.090", but you need to measure it.

From those numbers, I see your depth of neck pocket to be:

0.750" (neck thickness) + 0.156" (5/32", fingerboard thickness at E & G) + 0.050" (fretwire height)
- 0.406" (saddle height) - 0.090" (thickness of the bridge base plate).​

That comes out to a neck pocket depth of 0.460" or about 15/32".

Thanks George, that clears a lot of my confusion up. When I was writing that late last night, I forgot that my base plate is indeed included in the 13/32" saddle height measurement, but I'll double and triple check everything before I rout. On an off question: when measuring the 34" from the nut to the bridge, is that distance measured to the front set of screw holes on the bridge, the back set of holes, or somewhere else entirely? Thanks!

 

[megafiddle]

For the Gotoh Standard Bass Bridge, Stewmac recommends 35" from fretboard side of the nut to the rear mounting holes. For an example, the stock mounting holes on my Fender P bass are at 34 - 31/32", just about 35".

That placement should provide the saddles with sufficient adjustment range in either direction for that bridge and also for a standard Fender bent plate bridge. An intonated string in good condition will never have it's saddle at a position shorter than scale length. The lightest string (eg the G) will be usually be at scale length or a little bit more, so about 34" to 34-1/16". The heavier strings will be progressively further back.

If you locate the bridge at 35" to rear mounting holes, you should find that the G saddle can be set at 34" with just a little extra adjustment range to move it forward, to allow for error. And all saddles should have plenty of range to move rearward. The measurement to the saddle is to the witness point (take off point, where the string takes off free of the saddle groove).

With no specs to go by, I move the G saddle forward until there is 1/16" of adjustment screw extending from the front of the saddle. Then I position the bridge so that the saddle witness point is right at scale length. For round saddles, the witness point would be right at the center of the saddle. Scale length is a design value. It determines the position of the frets, and the minimum length position of the lightest string's saddle.

-

 

[Robert Sanger]

I have been researching the same topic and ran across this thread. Great information! My question is when calculating the pocket depth would there be any advantage or dissadvantage in taking string action into consideration? The example above has the string bottoming out on the top of the fret with the saddles all the way down (if measuring the E & G sides).

If the saddles are at their lowest position wouldnt you want the instrument to be at its lowest PLAYABLE action (or very close to it) instead of bottoming out on the top of the fret? Then you have more room to adjust upward for higher action?


Thanks!

 

[Bruce Johnson]

Well, the calculations above don't include what happens when the neck curves upwards under string tension, and takes on some relief. So, if you figure the depth of the neck pocket as described above, with the saddles bottomed and the strings sitting on the frets, when you actually string it up, you'll end up with what you are suggesting. That is, the saddles will bottom at the lowest practical action height, based on how much relief you have set into the neck.

Most bridges have plenty of upward travel of the saddles.

 

[Robert Sanger]

Makes total sense....Thanks!

Time to go route a pocket......