Official Luthiers Forum!

I modified this thread since I got the answer to my first question (Thanks!) but not fully on the second question I had asked.

Are you also flattening the top's small bout where the fretboard end is glued? If not, how are you handling the dome under the fretboard to ger a proper fit of the fretboard?

Thanks,
Ed

I use the center front to rear right to left..

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Don't need to locate the centre as the radius is consistent throughout. It shouldn't matter really where you locate the workpiece.

_________________
Doug

Don't let fear or common sense stop you from trying to build something

Yes. Just picture yourself standing in a 20' radius sphere with the inside covered in sandpaper. A radius dish is just a section of this awesome sphere.

I had not thought of it as a section of a sphere. Given that, as you say, it would not matter where it was in the dish.

Thanks.
Ed

Yes, but you could if you tried, take off nothing at the heel and maximum at the neck block, which would change the angle between the top and the side at this location.

Likewise. With respect to the where the FB lays on the top, I use a 25' radius on the top. I radius all top braces to 25'. On the UTB I leave a 3" centre section flat. Make marks and sand up to them in the dish. I have been doing this on the last 8 or so guitars and the geometry has been working out consistently perfect (or very close) every time. Prior to this method I was leaving the entire upper bout flat. I constantly ended up with more FB drop off than I liked. No more with this method.

Cheers,
Danny

https://www.youtube.com/watch?v=pz6xzVRA51E
if you really want to control this process using the Drive the bus technique works well for me. I rely on the center post as it makes this process repeatable and outcome reproducible. Free turning the dishes can have so issues. I will measure as I go and spinning is more efficient than rubbing.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I view the dish as a sphere, also. I try to get the endblocks down to the desired height and the waist heights equal.

Bingo! Doug nailed it!

Anywhere on the dish, if it's made correctly is the same radius and an exact location is not necessary.

Depending on your methodology it should not matter. If you radius the rim in the dish, driving the bus as John said, and then remove the rim from the dish and flatten the upper bout on a flat surface rim location in the dish is moot.

Re: Radius dish users: Flatten small bout under fretboard? How?
Hesh has a fantastic tutorial on this topic on his site.