Official Luthiers Forum!

Hey guys,

When bowl sanding do you guys actually sand into the wood (sides)? Or do
you set your kerfing high enough so you make contact all around but only
on the kerfing and not into the side itself? Hope this is a clear question.
Thanks for the help.

Ross

Rims and lining, that way you know that you have total closure between the top/back and the rims, every little bit of gluing area counts.

Don't go nuts when you get near the rims, just want to make sure that the entire surface is the same radius, take a pencil and mark up the entire edge (rim, head and tail block and lining), when the pencil marks are all gone, your ready to glue down the top/back.Rod True38812.1216666667

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http://www.bluescreekguitars.com/ar0007.htm
here is a link to my site to show this process. The sides are preshaped when I bend to get the aproximate radius. The jig is a simple set up you can make. I use chalk to mark the entire rim then sand till all the chalk is off.
john hall

The way I know I am done is when the bowl profile has been completely sanded into the neck and tail block. I mark the the neck and tail block with charcoal pencil and sand till all the charcoal is gone. This makes my neck and heal block maintain the domes radius rather than flattening over the blocks. I also mark the top of the linings just to be sure but they too are sanded complete, but if the neck and tail blocks are full profile then the rim should be as well.

The top is a bit differnt. I sand my radius till it gets just to the upper intersection of the x brace and rim. Then sand the remaining upper bout with a flat sanding board.MichaelP38812.4053935185

I preshape the sides before bending, but cut them just a tad large. After the blocks are glued in, I sand in the dishes, sans kerfed lining. Glue in the lining a little proud of the sides, mark with chalk, and sand until clean.

-Mark

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Hesh,
My answer is no, but maybe I am missing what you may gain by elevating the butt during the flat sanding of the upper bout.

When I sand the dome into the top I tilt the dome back 1 deg. I did this by drilling a bore in my work bench at 1 deg angle toward the butt of the guitar. that a 1" dowel sets in. My sanding bowl has a 1" hole in the center that this dowel goes through and the bowl rotates around the dowel during bowl sanding. This sands my dome rotated 1 deg toward the butt. ( not noticable but helps end the dome at the upper x brace/rim intersection without any sanding happening on the neck block during dome sanding.

P.S.
(I have four position screws that hold the assembly molds to my work bench in their proper position relative to the center line of the dome sand axis of the 1” dowel. Confusing to say in words but real simple once you see it.)

As far as the upper bout, I sand it flat with a 6" wide x 14" long sanding board. my objective here is to sand it flat and perpendicular to the rim.

I do not even think about my neck angle set till time to install the bridge then I set it at approx 1-1.5 deg. depending on scale.

Now as I have stated before I don't level sand my fretboard or install frets till after finish, the bridge is installed and neck angle is set, neck bolted in place and fretboard extension glued down. This affords me the opportunity to level the fretboard specifically to the installed bridge plane and final body conditions, and if the dreaded 14th fret hump happens, it is sand out during leveling. The issue you have with 14th fret hump is what drove me to this method and stoped me leveling and freting till final assembly after finish. I know most don’t like to level and fret after finish but I know I have everything dead on after leveling this way.

I plan to experiment with PaulW’s neck set and mortise fixture later this summer and also incorporate a bolt-down fretboard extension so all this may change at that time. But that is how I do it for now.
MichaelP38812.7136342593

Thanks again for the input guys. I love this place!

blessings,

Ross

To know you are where you want to be you should be markng reference points. I know what I want the tail to be and I usually take 9/16 to 3/5 off that for the neck.
That way I can establish the back wedge. I also know the depth. What I do first is square the top to the sides while in the mold. Then I know where the back should finish out
john hall