Modelling fret slots


I have worked up a fingerboard for a guitar and projected the lines for the fret positions onto the compound radiused surface.

However when I export the whole selection the fret lines don’t go. If I try to export them alone they don’t go.

Basically I would expect to cut the slots like routing along a line with a fine 0.023" bit.

Can someone please suggest a method for modelling fret slots so that they are exportable?

I have watched heaps of videos and even bought one on neckmaking and the one thing the dude omits is modelling the fret
slots!! - He doesn’t respond to enquiries.

It seems to be a common process, but I can’t crack it.


ac tually i’m using a Mac

What format are you trying to export to?
Can you attach your 3d file?

I was trying to export to an stl format so as to import to aspire for doing tool paths.

Fifingerboard 25.5 60226.3dm (114.8 KB)le attached


Is that right? Rule of 18, actually 17 something or another?

I would think that half of the export process is what you are translating it to on the other side. Perhaps try another format?

As you know, frets are basically a T shape with a rounded top, and a barbed tang that grips the slot.
If you do a CNC tooltath, it might be good to curve it to compensate for the fretboard radius, or you can go straight through.

If the slot isn’t wide enough, it will actually reverse-bend the neck. Too much, and you’ll have to glue them in.

[Once, I just printed out the scale, double stick taped the printout on the fretboard, and cut though everything. I used a guide-block to keep everything straight. Establishing a good center-line is a must, as is starting/ending at the right place.]

The STL file format only contains surface information in the form of meshes. It does not carry curves.

Aspire reads DXF which can contain curves. Not sure if Aspire will then let you use them in a sensible way - perhaps you should just model it in Rhino and export the finished part…

well…that’s what i thought i was doing…but the fret lines don’t go.

I will try another format.

I don’t mean to negative, but as a newbie there’s a lot i just don’t understand…


I’m not sure what that means…
The way I understand it, you were trying to export lines in an STL file. The STL format simply doesn’t allow you to carry lines.

…yes…I guess i’m learning the hard way.

Thanks for your patience.

How would you cut a series of lines across an oblong piece of wood? In cad to cam to gcode terms?


Is connecting the fret lines and making it into surface to export an option?

[disclaimer] I don’t do machining myself [/disclaimer]

The thing to understand here is that a line is not a physical reality and you want something cut out of wood - which is a physical reality. Normally, one would model all features in a 3D model and send that model to the CAM program which generates a toolpath over the surface based on input such as tool dimensions, etc. These toolpaths are then translated into G-Code.

I am not sure that you really want lines here - a straight section between two points. I’m guessing that you want the fret depth to follow the curvature of the top of the neck. [If not, getting the G-Code might be as easy as writing it manually in something like the Mac alternative to Notepad.]

Assuming curved cuts:
For your cuts to become a 3D object, you could make pipes out of the curves and cut into the wood part with those; manually trimming and splitting surfaces or using boolean operations (boolean difference). Just make sure that the input curves for the pipes extend beyond the neck surface.

Something like the attached.
fingerboard 25.5 60226-wd.3dm (674.7 KB)

Yes thanks.

Doing them on my tablesaw is a breeze compared to this…so far :o)


I thought about that which is why I put the curves at depth and on the surface, but I don’t know enough as to what to do afterwards…I’ll play a bit.


Right - a line has no width and therefore doesn’t exist.

The depth has to be a certain value at the ends. Following the curve of the surface is not imperative, but would be less cutting on a very small bit.

I’ll play with the pipes.

Thanks again.

Who is going to be creating these toolpaths?

Most CAM programs can use a line (curve) as input for cutter paths.
The question here is do you want to cut this particular shape as a 3d toolpath where the cutter nibbles a little bit off at a time with multiple passes or do you want use a cutter that has the shape of the slot groove and make just one pass for each fret groove??
This is the sort of question that only the programmer who is creating the toolpaths can answer.

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I would also say the curves are the right way for manufacturing. As the tang width of a fretwork is something about 0.02" (0.6mm) a 3d tool path would be less common.

These two methods I’ve found:
CNC Machining:

If you just want to model your project you are free to model any details, but for manufacturing you simply need a few parameters: material, radius, scale, number of frets, fretwire used. width, hight and probably offset for the nut. With these parameters a workshop should be able to get the job done.

Mate I do not EVER want see a fret saw and jig again.
That’s why I’m torturing myself here!! :o)

The little saw on the spindle looks good!


@RobSm :wink:
But why torturing? If you want to use the fret saw and jig you can use your curves as pattern. Usually you saw in the middle of the marker line. No reason to model the 0.02 fret wire gaps.

Yes the CNC machine is really nice :slightly_smiling:

Hi Rob,

Hopefully you still get messages from this very old post.

I am trying to do exactly the same thing, using rhino to create the .stl file for my ukulele fretboards to import into the vectric product to create my three d tool path.

My question is did you have any luck?

I will have to upgrade my vectric software to the newer version in order to use the three D import feature and do not want to waste one hundred seventy five pounds on doing so if it does not work. You can mail me direct at jen at ukulele dot uk dot com

Hi Jennifer.

I have had some success.

I drew up the profiled fretboard (no frets) in Rhino - that is tapered and radiused - and also in Rhino made a dxf file of the fret lines.

I imported them into V Carve aligned to the same spot, and did profile cuts for the fret lines using ‘the project onto curved surface’ option which is right before

I can’t remember if I did toolpaths for the fretboard itself at the same time but I think I did.

Hope this helps and good luck.