Cutting 0.6 mm Slots in a Guitar Fretboard with G18/G02/G03 Arc Commands

Hi. This looks so neet and tidy. I once made a fretboard with a very thin kerf Japanese saw which was nerve-wracking to say the least. I am slightly concerned about the fact you say you will use oak for the fretboard. Only because oak is notorious for going black in reaction to anything acidic and especially if iron is present, this is how ebonizing works and fuming if I remember rightly. Just thought you might end up with black marks between the frets from fingers on strings over time. Obviously you may have thought of this or might be staining it dark anyway but thought it worth a mention. Good luck, it looks awesome so far. Ollie.

Hi Ollie.

The fretboard will be painted with gloss black Rustins paint and then lacquered with Rustins Plastic Coating as per the original guitar so there will not be any risk of staining. I wasn't aware that oak had such a reaction, but then again it would normally be treated, e.g. with Danish oil when used as furniture. Most of our furniture (dining table and chairs, nest of three side tables and a large sideboard/display cabinet) is oak. It is all treated in some way.

I have the StewMac Japanese fret saw and fret slotting mitre box with a custom made fret slotting template, but it is a goal to make the fretboard fully radiused and slotted via CNC. The only issue I have experienced with with 0.25-0.35 mm thickness discrepancy but this was due to the test piece not fully flat on the MDF spoil board. I use double sided adhesive tape sparingly to hold the spoil board to the aluminium T-slot bed or else it is extremely difficult to remove and this was lifting. I think that I will have to make the final fretboard with the blank stuck directly to the T-slot bed to minimise this thickness discrepancy.

Doug

https://www.youtube.com/watch?v=XzWk-s1ILy8

In this video I demonstrate how to make a fully radiused and slotted fretboard (for my replica Brian May Red Special guitar) using CNC. There are seven stages in total; only six are shown in this video:

1. Thicknessing the 11.5 mm spruce stock to 7.00 mm using a 6.00 diameter solid carbide two flute flat nose end mill with 18,000 mm spindle speed and 2,500 mm/min XY feed rate in 1.5 mm depths per pass. Actual cut time 14 minutes. [Not shown]

2. Drilling 2 mm deep holes for 1/4" (6.35 mm) diameter mother-of-pearl fret marker dots using a 6.00 mm diameter solid carbide two flute flat nose end mill with 10,000 mm spindle speed and 750 mm/min XY feed rate in 0.5 mm depths per pass. Actual cut time 1m 51s.

3. Cutting the outline using a 6.00 diameter solid carbide two flute flat nose end mill with 18,000 mm spindle speed and 2,500 mm/min XY feed rate. The outline toolpath was generated in MeshCAM using the 'pencil cleanup' finishing toolpath option and then the output G Code copied and pasted for each pass (seven passes at 1.00 mm depth per pass). Actual cut time 3m 28s.

4. Initial (rough) radiusing to 6.50 mm thick at the crown using a 6.00 diameter solid carbide two flute ball nose end mill with 18,000 mm spindle speed and 2,000 mm/min XY feed rate. Stepover is 1.5 mm. Actual cut time is 10m 05s. [This section is speeded up x2]

5. Inserting the 1/4" (6.35 mm diameter), 1.3 mm thick mother-of-pearl fret marker dots manually. Actual time 3 minutes. [This section is speeded up x4]

6. Final radiusing to 1/4" (6.35 mm) using a 6.00 mm diameter solid carbide ball nose end mill at 18,000 rpm spindle speed, 2,000 mm/min XY feed rate. Stepover is 0.5 mm. Actual cut time 28m 20s. [This section is speeded up x4.]

7. Cutting the fret slots with a 0.6 mm diameter solid carbide flat nose end mill, 10,000 rpm spindle speed, 600 mm/min XY feed rate. Actual cut time 14m 49s. [This section is speeded up x2]

For the marker dot drilling toolpath, the initial and final radiusing toolpaths and the fret slotting toolpath, I wrote the G Code myself (instead of using MeshCAM software to generate it) using the G18 command to generate arcs in the XZ plane and G02 and G03 commands for clockwise and counterclockwise arcs.

The wood is spruce tonewood left over from the blockboard assembly. This is another test cut; the final fretboard will be cut from oak. The video will also be on my YouTube channel and my guitar blog. The total time to execute this job was 1h 15m.

Doug