[cmjohnson]

Cyborg, have you added the waist cut to your model? The waist cut makes the PRS double cutaway design the most comfortable guitar to play that I've ever encountered, beating even a good Strat.

CJ

[Phaêton Guitars]

Hi from France,

As you can see on facebook http://www.facebook.com/PhaetonGuitars , i'm a young luthier and i haven't never build "Inspired by PRS".
I read often this forum as visitor but my english is so bad that i never write a thread. In France, we haven't the same forum regarding guitars building with CNC. We are an old country with traditions. If you build with cnc, you are a wicked witch and what we do to the witch ? the stake! the stake!
When a luthier use a cnc, he lie low.

Today, i have a question in my mind and i wish a answer.

Mr cmjohnson, my question is regarding the tenon (and of course the neck heel)
My apologizes, i can't use words to explain my question, so i place 1 photo hereafter. I hope you'll understand.

Thank you in advance,

[cmjohnson]

The tenon on a PRS guitar is like in A in blue.

The tenon follows the width of the fingerboard.

Tenon taper = fingerboard taper.

The tenon is not straight.

The way I taper the fingerboard, and also the body, is to use this fixture:


How it works:

The fixture is set up in the mill. The fixture has one bolt holding the upper piece to the lower piece, at the nut end. (Left end as facing the mill.) This acts as a hinge.

On the right side of the fixture, the body end of the fingerboard, there are three holes in the upper piece, and three tapped holes in the lower piece.

They are arranged so that when the upper fixture at the right side is bolted to the lower piece of the fixture, using a precision ground shoulder bolt for repeatability, then the bolt may only go in one of the three upper holes, and whichever one you choose, it can only possibly go into a single one of the lower holes. You can not put the bolt into a bad hole combination.

The center hole is for cutting parallel to the center of the fingerboard.

The hole closest to the operator is used and the bolt placed, to cut the treble side of the fingerboard to the correct angle.

The hole farthest from the operator is used and the bolt placed, to cut the bass side of the fingerboard to the correct angle.


This is also used to cut the neck mortise on the body. This is done by using double sided foam tape and taping the body to the same fixture, being very careful to align the centerline of the body on the centerline of the fixture.

The fixture has a scribed centerline. That centerline is also a known distance from the front end of the two lower blocks of the fixture. These operator
trams in on these blocks and then he has his reference for the whole fixture.

With the cutter centered over the fixture centerline, I switch to a small drill
bit used as a pointer, and place the body on the fixture so that the seam between the halves of the maple top is perfectly centered on the fixture, underneath the drill point across the full length of the body.

When the body is properly positoned, I zero the DRO on the centerline, enter tool diameter compensation for the chosen cutter, and begin final cutting the tenon to its taper and width. I like to leave the tenon tight enough that it is necessary to sand the side of the neck tenon to get a good fit.











Here are more pictures of some of my guitars that I have made.


As for the use of CNC, it is necessary in a busy shop. But a good builder
does not expect the CNC equipment to make a perfect guitar. Some hand work is always going to be needed to make a GOOD guitar.

[CyborgCNC]

You do AWESOME WORK!! Great Guitars and Build!! Congrats!

(BTW: LOVE the Archtop!!! :-) )

[Phaêton Guitars]

Mistake Cyborg

I'm the owner of the brand Phaeton but the Phaeton model is a guitar of the TAO brand, a factory who have nothing with me.

[beekhay]

Hi. I'm designing a guitar for CNC cutting with a friend. I'm not an expert with Solidworks but I know my way around it. I've been struggling for weeks to wrap my head around how to model the contours of the top of the guitar and I'm hoping you can help me. I read some of the messages on the thread and your responses. I respect that you can't send your file to others since that guitar is not your design, but is there another model of yours with similar contours as on the face of the PRS that you could share so I could learn from your techniques, or maybe suggest a particular tutorial you've made that teaches the techniques you used to make this beautiful PRS model? I'm beating my head against the wall and the youtube tutorials out there aren't helping me.

[cmjohnson]

FYI, Grabcad has a lot of downloadable cad files of various types and descriptions, including a fair number of guitar related files.

[asuratman]

cmjohnson,
I lsot your picture, do you have link to your website to see your pics.