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Tutorial: CAD and CAM for Luthiery

Discussion in 'Luthier's Corner' started by Beauchene Implements, Feb 1, 2013.

  1. The luthier's corner has been good to me. I've learned most everything I know about bass building from y'all, so I feel it's time for me to give back. Here is a tutorial on Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM), with the end goal of CNC machining a bass guitar in mind.

    I learned how to make my first bass in 2008 by hanging out in this forum, but I've been designing things in Rhinoceros for fun since 1999; at this point I can get it to do what I need. In 2012 I built a CNC router as a bridge between my CAD hobby and my bass building hobby, and I had to overcome a steep learning curve to put it all together. But at this point I've built 3 complete instruments with CNC assistance, plus a few unassembled bodies and necks.

    I was originally going to make a build thread featuring my CNC machine in action, but there are already some great CNC build threads here. So instead I thought I'd demystify the process, show what goes into it before you ever turn on the router.

    In this tutorial we will design a bass in a modeling program, then turn the design into gcode files that the CNC machine uses to cut out the parts.

    The software that I will be using is Rhinoceros for the 2D and 3D design, CamBam for 2.5D gcode, and MeshCam for 3D gcode. There are hundreds of other programs out there with perhaps better features, but I can get it done with this relatively inexpensive suite.

    Below is an outline of steps, and links to videos where I'll work my way through this method. If I do something you have questions about, feel free to ask.I don't intend it to be a full introduction to Rhinoceros; there are hundreds of videos already for that.

    Over the next few days I'll update this post with video links, and expand the outline below.

    Video 1: Setting up Rhino file, establishing critical dimensions
    Video 2: Drawing a body from an image and from scratch, drawing headstock
    Video 3: Pocket and cavity design, 3D neck back design and analysis

    1. CAD (Rhinoceros)

    1. Open a new file, go to "file>save", and save it.
    2. Open "file>settings>units", adjust page units to your preference, metric or imperial. Set tolerances.
    3. Open "file>settings>grid", set grid size, major and minor grid lines
    4. Open "Rhinoceros>preferences>modeling aids" for nudge settings (key,distance and window), snap settings


    00. design considerations (entering arguments)
    a. Scale length
    b. Number of strings
    c. Bridge spacing
    d. nut width
    e. general body size
    f. hardware/pickup choices

    01. Centerline scale length (34" scale centerline)
    02. Nut width (1.5" nut)
    03. Bridge width, Bridge spacing (2.25 bridge /4)
    04. Bridge placement. envelope of saddle adjustment considered.
    05. 1/4" outside of outer strings, neck lines
    06. Scale lines
    a. Determine string gauges you'll use, then add them. DR Lo Riders medium: G.045 D.065 A.085 E.105 = .300
    b. Subtract total string width and desired edge width from nut width: 1.500-.125-.125-.300=.95
    c. Divide this number by the number of between-string spaces (3 for a 4 string bass) to get the spacing: .95/3=.3166
    08. Strings w thicknesses
    09. guide lines for general body size, strap hang point. Clearance for fingers.(horn at 12" fret bottom horn 16th fret 3" below neck, 2" above 9" wide hips
    10. Pickup type, placement.
    11. Knobs
    12. tuner post diameter, tangent to string


    01. Sketch body, pull control points until shape is practical and pleasing.
    02. Same for headstock headstock.consider tuner pegs.
    03. Electronics cavity. design after you're happy with body shape
    04. Knob placement.

    D. SIDE PROFILE: While not used much to generate gcode files, the side profile will help you determine thicknesses of the body, neck and fretboard, depths for cavities, neck angle, headstock angle, etc. It will also help you to decide what thickness stock you will need to achieve your desired result.

    01. Body thickness
    02. Neck thickness
    03. Neck angle
    04. FB thickness
    05. Headstock angle
    06. Pickup cav depth
    07. Electronic cav depth

    E. 3D lofting

    01. Body only needs lofting for 3D contours.
    02. Headstock faces, if milling from a solid neck blank. If chop/flipping headstock, you can skip this.
    03. Neck back contour
    04. Volute
    05. Heel
    06. Flip things that cut from the back
    07. Truss rod channel (if curved)
    08. Establish index pins

    2. CAM

    A. 2.5D (CamBam): 2.5D refers to machining to shapes down to a specific depth. Think of making a heel pocket or pickup cavity with a router; that is 2.5D.

    00. Export files from Rhino. DXF files for 2D.
    01. Index
    02. Heel pocket
    03. pickup pockets
    04. Bridge holes
    05. Elec cav
    06. Contours: Stepover considerations

    B. 3D (MeshCam): only for neck backs and carved tops.

    00. Export files from Rhino. STL files for 3D objects.
    Deep Cat likes this.
  2. Just uploaded the first video, see link in first post. I made a better video than the first one, I tend to ramble so I apologize in advance. Looks like YouTube is still chewing on it so try again later if it doesn't work.
  3. suraj


    Oct 1, 2008
    Mumbai, India
    This is awesome..!! I'm really glad you're sharing your knowledge with the community and this will be of great help. Personally i'm waiting for the CAM bit, but even your first video is pretty thorough for the beginners. Thank you :)
  4. chiselhead


    Mar 18, 2009
    Knox, New York
    I just watched your video. Great job! I can't wait for the next installment
  5. Stealth


    Feb 5, 2008
    Zagreb, Croatia
    Sir, you are brilliant. I'm subbing.
  6. Torzal

    Torzal Commercial User

    Dec 25, 2002
    Austin, TX USA
    Owner: Little Guitar Works
    Great video, thanks for sharing. Perfect timing for me, too, as I'm building my CNC machine. I noticed you're using Rhino on a Mac, is that the version that's still in development?
  7. Thanks everyone. I just uploaded video number two, see first post for link. Give it a minute if it doesn't load. I noticed last night that it takes about an hour for the HD version to become available.

    Torzal: it is Rhino for Mac, the beta version. I've been using the beta version for about 5 years now! The release should be out soon, Rhino 5 just shipped for Windows.
  8. Phil Mailloux

    Phil Mailloux

    Mar 25, 2005
    Brisbane, Australia
    Builder: Mailloux Basses
    Very cool videos so far, I even learned a few things there, I had no idea how to draw from a picture in Rhino, I always use CoreDRAW for that and upload that file to Rhino to finish off the model, I can finally do it all in one place now, thanks! I'm pretty keen on seeing your toolpath videos now, chop-chop get to work! :D
  9. Reticle


    Jul 24, 2009
    Charleston SC
    Man, thanks SOOO much for posting these! CNC has consumed my life! I swear, every free minute I've had since getting my machine has been spent drawing or cutting.

  10. Hey guys, glad they've been helpful! I just moved into a new house, then got buried in a snowstorm, and finally got internet in the new house today. I'm working on the next vid now, I'll try to have it up in the next 24h.
  11. Wengewood


    Feb 7, 2012
    Fantastic job!!!
  12. AltGrendel

    AltGrendel Squire Jag SS fan. Supporting Member

    May 21, 2009
    Mid-Atlantic USA.
  13. mikebpeters


    Aug 29, 2011
    NS, Canada
    Thanks so much - I'm three small parts away from having everything I need to build my CNC machine, and then I needed to start down this path!
  14. T-34


    Aug 11, 2005
    France, Paris region
    Man, you're awesome.
  15. abarson


    Nov 6, 2003
    Santa Cruz
    Sticky this!, sticky this, sticky this!
  16. T-34


    Aug 11, 2005
    France, Paris region
    sticky sticky sticky this, yeah baby!
  17. Hey folks, link to third video posted, see first post. This one shows how I do 3D neck backs, I know their is some interest in that.

    Sorry for the delay. My Dad passed away two weeks ago, so along with moving my family into a new place and getting ready to start a new job, this kind of fell to the bottom of the heap. trying to keep it moving though. Staying busy is good.
  18. Reticle


    Jul 24, 2009
    Charleston SC
    Man, so sorry to hear about your Dad.
  19. Musiclogic

    Musiclogic Commercial User

    Aug 6, 2005
    Southwest Michigan
    Owner/Builder: HJC Customs USA, The Cool Lute, C G O
    Hey Adam, my prayers are with you man, hope all is well and getting a little better each day.
  20. My condolences Adam,