... so that the work will not move during execution of the program. 

Profile toolpath

Set UP the Machine    The machine deck (spoilboard surface) should be a true plane and parallel to the path of the the machining bit. Sweeping the surface with a large diameter (2") bit will ensure that the surface is true, but large bits are very expensive and small bits (3/4") take forever. A solution is to make the spoilboard as small as possible.


     For my fretboard inlays, the spoilboard is the top surface of a support fixture... built specifically for this purpose. The 4"x20" top is only slightly larger than the fretboard.  I can sweep the surface with a 3/4" bit in about 3 minutes.  That way, I know that my spoilboard surface is true and parallel to the bit.


     The support fixture pictured here is 4'' tall.  The MDF work surface is 4" x 24".


​​Prep Steps Explained:(briefly)

... the first toolpath at a safe Z distance above the work.

     It is very important to think about how one will secure the ebony fretboard blank to the fixture surface. It helps to keep the fretboard stock as large as possible in the waste areas so that it can be screwed, clamped, nailed, and/or glued to the spoilboard... using only the waste areas outside the fretboard.  Make sure that you do not intrude on the path of the router bit or the gantry and that the work has no chance of moving as the various router cuts are made. 

      Likewise, the hold-down clamps must rigidly secure the support fixture and be out of the way of the gantry. My support fixture is taller than the hold-down clamps so that the clamps will not be in the way of the CNC gantry.


   The last photo shows the finished fretboard sitting on top of the fixture. The order in which processes were completed goes like this.


Setting Up the CNC machine:

  • Sweep the spoilboard surface; true and parallel to the path of the bit. (3/4" bit)

  • Align and secure the fretboard blank to the spoilboard. Be sure that the fretboard center line is parallel to the bit path.

  • Do not move the fretboard blank until all tooling operations are complete (very important). 

  • Determine the zero datum points for all three axes (X,Y,Z).


Routing the Fretboard:

  • Contour the surface of the fretboard to the desired radius (1/4" ball nose bit, Moulding toolpath). Woody uses a 12" radius fretboard surface.

  • Rout the fretslots (0.025" End Mill, Profile toolpath, straight line, multiple passes)

  • Rout the inlay pockets (0.625" End Mill and 0.025" End Mill, change bit)

  • Rout the fretboard profile.  (1/8" End Mill, Profile toolpath)


ZERO THE MACHINE

...the toolpaths.

Software

EXPORT 

Pocket toolpath

DRAW 

...the design in a vector software. Vectric 9.0 came         with the machine.  (NextWave HD-4)

Pocket

January 2020


     Mother of Pearl


          : CNC Fretboard Inlays

          

The Post Processor converts toolpath to machine language. The selection of a Post Processor is specific to the CNC software.

SET UP THE MACHINE 

Hardware

... the desired toolpath.

SECURE THE WORK 

​​Prep Steps:

Note: When closed, the clear shower curtain completely surrounds the CNC.  This keeps dust out of my home heating and cooling system.

Profile

SELECT THE TOOLPATH

Moulding

EXECUTE

TEST RUN

Moulding toolpath.  

INSTALL

...so that the center line is parallel to the path of the cutter. 

​​ NOTE    Tutorial Videos are very helpful.  I found the book and videos that came with the NextWave HD-4 exceptionally well organized and presented. Video presentation, however, must assume that the viewer already knows some things.  The universe is not flat, square and true.


     Many newbies find out that learning to program and operate a CNC is more difficult than expected.  It takes study and practice to know confidently that the final execution will meet the intent of the original design. There are just alot ofways to screw things up or get them out of sequence.  


     With 3 whole years of first-time experience, Woody has attempted to provide insight for others who might be thinking about investing in a CNC. It is endlessly challenging... if you like that. Woody certainly does.  


     This presentation has been brief, but not comprehensive.  We have only touched on a few basic things that must be thoughtfully considered when setting up and executing toolpaths via computer numeric control (CNC). If you would like to hear more on this, let me know.

SET UP THE JOB 

... in all three planes (X,Y,Z).

Profile toolpath

...to the CNC (via flash drive).

​     Unfortunately, this photo has screen-shot clarity.  I hope that you get the idea. One must first draw the project precisely.

PROGRAM AND EXPORT     The Toolpath icons are in their own drop-down menu.  In order to program the toolpath one selects the vectors and the operation to be performed. Then, click "Calculate" and the CNC program is written. 


     Below is a picture of the icons on the toolpath menu in the Vectric software. Hovering over the icon brings up the name of the operation, e.g. Profile, Pocket, Inlay, Moulding, Drill, Engrave, etc.  Again, don't hesitate to use the demonstration videos to learn the function of each.


​     Once the toolpaths are created, saving the toolpaths requires the selection of a Post Processor. The Post Processor reads the toolpath code and converts it to machine language.  There are dozens of Post Processors to choose from.  Your software vendor  should tell you which processors are compatible with the toolpath code in your software.


       When the toolpath files are complete we need to export them to a flash drive. These are the machine language toolpaths that are input into the USB port of the CNC controller. 


PROGRAM 

... the correct bit with the correct feed and speed.

Hardware:   Now we get into the mechanical side of it.


SET UP THE JOB and DRAW     Learning to set up and draw your design in a vector program is essential and relatively easy once explained. Knowing the purpose and procedures for each of the icons on the Drawing toolbar is basic.  Each software, however, is different. Demonstration videos from the software vendor should help in this regard.

      Below is pictured the Vectric Job Setup form in which one inputs the job type, dimensions and the X, Y, and Z datum positions. 

     On the Drawing toolbar one selects the tools that are needed  to create and edit the vectors (lines, circles, squares, etc; also text and dimensioning tools).  These are your drawing tools.  One has to learn how and when to use each in order to draw vectors efficiently.

Finished inlays

Profile toolpath

... From the toolpath list, select the correct toolpath for each process.

​True and parallel fixture surface.

Inlay

Pocket toolpath

Drill

Woody is happy to answer questions.


Woody@WoodyStrings.com


I hope to see you back here next month,


Woody​​


POSITION THE WORK 

...so that the spoilboard surface is true and lies parallel to the plane of the bit path.

... Input the job dimensions and select the X,Y, and Z zero positons.

         Fretboard Inlays with a CNC rig are about as basic as one can get with programming and maintaining a new CNC machine. A caution, however, is that without diligent preparation and execution, there are many more ways to get it wrong than to get it right.

      I've been using a CNC machine in my home shop for only a few years. I like it.  Unfortunately, I have only been able to dedicate a few months each year to learning and operating the CNC system. The challenges are unending.