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Discussion Starter · #1 · (Edited)
Test cut in Poplar of a compound radius guitar fingerboard. Model created in Fusion 360.
Length - 20"
Width - 2.5"
Thickness - .25"
# of Frets - 22
Scale - 25.5"
Radius - 12" at nut, 20" at body
Fret slots cut with .5mm bit because I didn't have a .6mm handy
 

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Discussion Starter · #3 ·
Poplar may be a good practice piece, but won't hold up to strings. It's usually not hard enough.
This was just to test cut to verify the G-code and not meant to be used on a guitar. Sorry, thought I made that clear in the OP.
 

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Discussion Starter · #5 ·
I keep saying I want to try cutting a fingerboard on the CNC, Ed, but have yet to do it. What guitar will this go on? Your test looks good, btw.

David
Thanks, David.

My nephew builds custom guitars, all handmade, no CNC, and a few days ago we were discussing the difficulty in manually making a compound radius fingerboard. I asked him to give me some parameters and I'd give it a shot on the CNC. I doubt I've convinced him to add a CNC router to his shop as he really enjoys doing things "old school", but for this particular piece of the puzzle, a compound radius fingerboard, CNC might be the best way to achieve consistent results.

Attached are some pics I just received yesterday of his latest creation.
 

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That is gorgeous!! How thick is the top cap and what wood is that? In the third photo on the deck it appears to be the full thickness of the body but the back is clearly a different wood.

On the acoustic I'm building I used a compound radius fingerboard and cut it by hand - 14" and 18". I just happen to be working on it today and took some photos when I weighed it so these are current -

Guitar Acoustic guitar String instrument String instrument Musical instrument

String instrument Guitar String instrument Plucked string instruments Musical instrument

David
 

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Discussion Starter · #7 · (Edited)
That is gorgeous!! How thick is the top cap and what wood is that? In the third photo on the deck it appears to be the full thickness of the body but the back is clearly a different wood.
David
He said overall thickness of the body is 40mm with the Spalted Maple top being about 11mm or 7/16" at the thickest point. Here's the description he sent with the pics: "Spalted Maple Burl Top. Black Limba Back. Maple/Wenge 5 Piece Neck. Gaboon Ebony Fingerboard. Geppetto Guitars Pickups. 2 volume, 1 tone. Hipshot Kickass Bridge. Hipshot tuners. Turquoise inlays. Odies Oil finish."

How did you do the radius on yours, just sand and use gauges to check for accuracy? It was pretty simple to do in F360 but took some time to cut. If I do another one I'll use a parallel toolpath running lengthwise rather than across the fingerboard. That should cut the machining time down considerably.

Nice job on the guitar!
 

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Discussion Starter · #9 ·
I had to edit my previous post. He said the top was 7/16" at the thickest point and I did the conversion for 5/16".

That's an interesting jig you made. Is the crank handle on the side just used to hold the router in position as you make the pass?

If you're making a fingerboard with a compound radius, a different radius on each end, how do you use the sanding blocks to achieve the transition from one radius to the other? For example, the sample fingerboard in the OP has a 12" radius at the nut and a 20" radius on the body end. I'm just trying to visualize a jig that could be used to do that.

Ed
 

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The crank is to pivot the router left to right. I turned it a little at a time to cover the entire cove cut. If I used the fixture more I probably would modify the crank so it stays put when you turn it but I had to keep holding it in place. No biggie since I was only making two.

I sanded the fingerboard from the nut to about the 7th or 8th fret with the 14" radius and from about the 7th or 8th to the end with the 18". I sort of let the two overlap around the 7th and 8th frets. It's really difficult to feel the transition anyway. You can tell the section above the 9th fret is flatter than the first few frets but I think if you didn't know it was a compound radius you'd probably miss it.

Now on the electric bass with 12" and 20" it might be more noticeable, but 14" and 18" is just very slight. At least it is to me.

David
 

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Discussion Starter · #11 ·
Now on the electric bass with 12" and 20" it might be more noticeable, but 14" and 18" is just very slight. At least it is to me.
David
Thanks for the explanation; makes sense to me. The board I cut wasn't for the electric bass, more of a general proof of concept. lol It's a parametric design that can be easily modified for any radius, compound or single, and for any length and scale. I don't know what angle(s) he used on the bass, but it seems like a very long neck, which I guess you need on a bass.

Ed
 

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Most beautiful guitar I have seen in a long time. James jj777746
 
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