Hello

[Craig Regan]

Graduating the top.
I made a special table/cradle to hold the top plate.
Today, I will start to carve out the underside of the top deck.

[Arnold Schnitzer]

I see you have posted a graduation drawing. That thick ridge down the center is not traditional,. It is typical to work in more of an oval manner out from the thickest center zone. I believe the drawing is from the Chandler book, which contains some good basic info but is short on specifics. You will want to cut your f-holes while the top is still a bit heavy. Otherwise you will be cursing everytime a little tear-out episode happens on the inside.

[Craig Regan]

Thanks Arnold, I was hoping to get some feed back BEFORE I start carving, possibly saving me from foolish errors.

My back plate has the oval type of graduation, so I am familiar the pattern. Also, the oval pattern seems to be common in the other string instrument family instruments.

As far as the f-holes go, should they be cut with the little knives, or are the knives for paring to the line? I was thinking of using a small coping saw and possibly drill bits for the circles.

Again, Thanks for the info.

[Arnold Schnitzer]

Originally Posted by Craig Regan

Thanks Arnold, I was hoping to get some feed back BEFORE I start carving, possibly saving me from foolish errors.

My back plate has the oval type of graduation, so I am familiar the pattern. Also, the oval pattern seems to be common in the other string instrument family instruments.

As far as the f-holes go, should they be cut with the little knives, or are the knives for paring to the line? I was thinking of using a small coping saw and possibly drill bits for the circles.

Again, Thanks for the info.

Cut into the wood on the outside with a knife and scribe the line so you don't get tear-outs past the edge. (I pare twice so I actually have a little channel.) Then use whatever tools you want to chop out the bulk; pare to the line; clean it all up.

[Craig Regan]

Thats the author of this thread drilling holes on the underside of the top. Its cold, so I am wearing a coat, hat, and scarf.

Chopping it out by hand.
At the moment, there is little, in the way of extra funding available for a power carving machine, (we are saving every penny for the fingerboard).

[Craig Regan]

I got rid of the bulk of material so the top would be easier to work with.
The thickness is about 15 mm overall, or a heavy 1/2".

Now is the time to retrieve my luthiers notebook and figure out my graduation patterns.

[Craig Regan]

I am building from a Peter Chandler plan. His graduation pattern for the top plate has a thick 8 mm center "spine" running top to bottom. Here are some ideas for different patterns, for thinning the top.

The first is a simple peanut type shape. Starts off thick in the middle and gradually thins at the edges. Seems simple and straight forward.

The second is based on a cello pattern. Ovals in the center, thinned out in the upper and lower bouts or "lungs" as they are sometimes referred to in this sort of pattern. Good pattern for cellos and violins but unsure with double basses.

What is the accepted "normal" patterns used by manufacturers past and present?

Would the tea leaf and audio oscillator set up help out in this situation?

The further I go on this project - the less I know.
If anyone wants to chime in on graduating top plates, the forum is open.