Inventables Community Forum

Cutting Guitar Fret Slots HELP!

Hi there. I’ve been carving out guitar bodies and necks and have now reached the fretboard.

I’ve been doing research and everyone has been using a .024" bit to cut the fret slots. So naturally I did this. .024" end mill, DeWalt 611 speed set to 1, approx 10 ipm, .01 doc. The issue I’m having is it cuts the slot way to wide, even though it’s cutting a simple straight line. To try and correct this, I bought a .020" bit… same thing. The frets just slide in and out and have way too much room. What would be causing this? I even got as small as a .015" bit and the frets still are too small. I even went and found fretwire with the widest tang I could and still no go.

Any ideas? Thanks in advance.

I use Illustrator using just normal paths, make a straight line. It doesn’t appear in any way my machine is moving left or right while cutting. It looks like it’s just cutting a simple straight line.

Do you have a way to accurately and precisely measure the width of your cuts?

are you 100% sure about the fret thickness?

I’ve noticed some issues before with the wasteboard being level. I think I will try better leveling it. Any recommendations on milling it flat?

don’t use the .015" bit for that :metal::sweat_smile:


Well, I was going to ask basically the same question as the OP, but was wondering what any luthiers have used to successfully cut fret slots.

Do you have a precision collet?

Cutting with a hand saw, we create a .023" wide slot. I cannot imagine a Dewalt 611 running without some play in the spindle, so I would guess that a .022" or .021" might be the largest bit to use. If there is still too much slop in the cut slot, I would say that your CNC setup (primarily the spindle’s micro-wobble), is just too loose for this task.

…but I’d love to hear from anyone that has successfully cut fret slots in a fingerboard using an X-Carve.

I used my laser to lay out the fret slots on a maple fretboard, worked like a charm!


I use 0.5mm end mills. Successfully cut slots in pau ferro and ebony. Works great for inlay work too.

0.2mm doc @ 50ipm which is conservative, but these do break easily if you get aggressive.


Sorry to be a doofus Rich, but what do “doc” and “50ipm” mean?

DoC = Depth of Cut (per pass)
ipm = Inch per Minute, CNC feed rate.

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For folks who are confused about terminology, there’s a community-maintained glossary at:

(also available in French and Italian)

Hopefully it’ll help folks.