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A while ago I talked about a project that I have in mind, building a parlor guitar. I mainly build classical. I only built three steel strings and always had a hard time getting the neck angle correctly. All the information I can find around is on setting neck angle on a 000 or somehow large guitar. But what if you build a small guitar? Shorter scale, thinner bridge. I guess that everything must be set up since beginning. Maybe even the radius of the top bracing? Because all this factor will affect the neck angle. I don't think you can modify the neck angle just by shaving at the heel. Otherwise you might end up with a discountinuous plane between neck and soundboard. This has been puzzling me for last couple of days and I can't come up with a solution.

Nice reply. Thanks. I have it a little bit clear in my mind but there is something that I do not understand from your reasoning.

1. At the beginning of your post you say: "You'll still want the same string height above the top, and the same string path height above the 1st and 12th fret, so the measurements are similar."
In a small, parlor guitar usually the bridge thickness is usually 1/4". In a jumbo you can get a bridge as thick as 3/8.
So if "Desired string height over top at saddle: .500" (my desired value for top to underside of string)"
in case of jumbo, you would have only 1/8 bone sticking out of the slot. On the other hand, on a parlor guitar, with a bridge only 1/4 thickness you would have maybe 1/4 saddle protruding from wood. Isn't this too much? Maybe in your thought you imply the the thickness of the bridge does not change from parlor to jumbo?

2. You say that "Top radius, etc. does not play into this," and I do not understand this. if you build flat the bridge will lay on the same plane of the neck. But let's say that you build (let's exaggerate) the top with a 10' radius, you would lift the bridge from that plane of a certain amount. Why doesn't this play a role on the whole geometry?

3. This is still related to top radius. I thought you have to take care of the top radius because if you only adjust the string heigth by changing the neck angle at the heel, you might get a discontinuous surface where the neck intersect the soudnboard. If you want BOTH the neck AND the soundboard to lay on the same plane, I think you need to have a certain slope on the soundboard that corresponds to the slope you are giving the neck. Is this correct? Well, how do you obtain this?

I hope this is not too confusing.

On all my guitars you can lay a straight edge from the neck block to the bridge and it's dead flat till it falls away from radius. I've actually been building true flat tops lately but anyway... There are lots of ways of doing this but what I have adopted using a bolt on neck is to rough it like Todd just said and then finish it off so that a straight edge along the fretboard dead center hovers about 1/32in over the the top of the bridge at the saddle slot.

So weather you do this with the fretboard glued and frets in place or just do measurements like Todd does if the straight edge is just a hair higher than your bridge then you should have good action (3/32 over the 12th fret) with a saddle about 1/8th to 5/32nds high. A 1/4 in saddle would be way too high IMO.

Ok, but please let me clarify that I took for granted that the bridge thickness was lower on smaller guitars. I think I read it somewhere. It can be a coincidence but even the AL plan for Martin 1-18 calls for a pyramid bridge that is 1/4 thick. Other than this, I think I understand the concept.

I like to get 6/32nd of saddle out of the slot with an action of about 3/32 on the bass side and 2/32 on the treble. This seems to not only give you room to raise or lower the action but leaves a bit of comfort space years down the road should you need to lower the action at the saddle. That's for a 3/8th bridge. I think for a 1/4 in bridge I'd probably only want to get a saddle height of 1/8th.

So for a 1/4in (8/32in) bridge I would measure a straight edge along the fretted fret board right over the saddle location to be 8/32 (bridge) + 4/32(saddle) + 1/32(distortion estimate) = 13/32in.

I really wish I had started building in metric units