Shaping First Saddle - Question

[murrmac123]

Originally Posted by Howard Klepper

Compound radius is not really relevant to whether the saddle must be flattened to get the action lower on the high E than it is on the low E. We can do away with the compound radius part by assuming that the saddle radius is that of the conic surface described by the compound radius projected to the saddle location.

So to the question whether one must flatten, i.e., increase the saddle radius to get an action differential between high and low E: no, it is not necessary. I do the saddle adjustment (and Steve, too, if I read him correctly) by first radiusing the top of the saddle, and then moving the center of the circle of which the saddle top is an arc down and towards the low E. Put more simply in terms of method, first arc the saddle top to the radius of the projected cone. Then lower the treble side of the saddle bottom more than the bass side. The radius of the top of the saddle remains the same, but it no longer lies on the same conic surface as the fret tops. All you have to do is mark the amount that must be taken off under the two E strings to get the desired action, draw a line connecting the marks, and sand to that line. Works a treat, and puts all the intermediate string heights right in proportion.

Howard ...everything that I have posted so far is only relevant to constant radius fretboards, and the presumption that the arc of the saddle is radiused to the same radius as the fretboard ... if you want to shift the goalposts by discussing compound radius fretboards , and increasing the saddle radius to take account of fret height, and desired action height, then OK .. but that was not the original topic.

[brianhejh]

Hi Guys.

A lot of great information here.

If the first fret is set at an 11th of the measurement of the desired 12th fret height.

My question: Does this same measured increase continue over the 13/14/15/16/17 frets before the fall away.

I am trying to understand this relationship (in particular) when one identifies a hump in the fret board over the body if so what are the options to fix the hump to correct/maintain the desired 12th fret height. Is it as simple as levelling the humped frets to the desired 12th fret height.

Thanks

Brian

[murrmac123]

Originally Posted by brianhejh

Hi Guys.

A lot of great information here.

If the first fret is set at an 11th of the measurement of the desired 12th fret height.

My question: Does this same measured increase continue over the 13/14/15/16/17 frets before the fall away.

I am trying to understand this relationship (in particular) when one identifies a hump in the fret board over the body if so what are the options to fix the hump to correct/maintain the desired 12th fret height. Is it as simple as levelling the humped frets to the desired 12th fret height.

Thanks

Brian

OK Brian ... I can tell you what the optimum set-up is ... when the guitar is strung up to pitch, (and the relief is correct) if you lay a straight edge along the frets , the straight edge should make contact with the first fret and the body joint fret (with a relief gap in between) ... ideally you should also make contact with all the upper frets beyond the body joint fret ... but if there is fallaway, then there will be an incremental gap up to the last fret, (which is fine ).

What there should NOT be ...is a visible gap at the body joint fret.

[Howard Klepper]

Originally Posted by murrmac123

Howard ...everything that I have posted so far is only relevant to constant radius fretboards, and the presumption that the arc of the saddle is radiused to the same radius as the fretboard ... if you want to shift the goalposts by discussing compound radius fretboards , and increasing the saddle radius to take account of fret height, and desired action height, then OK .. but that was not the original topic.

Murray: Everything I posted is as relevant to constant radius fretboards as it is to compound ones. I thought I explained why.

[Rodger Knox]

Originally Posted by murrmac123

Howard ...everything that I have posted so far is only relevant to constant radius fretboards,

Murray, I was pretty sure you process included leveling alone the string paths. If that's the case, you are actually creating a compound radius.