Radius Block for 8" Peavey Fingerboards?

Cnivek61

Cnivek61

Jul 17, 2017
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#1
Not sure if this post belongs in Lutherie or Setup and Repair, but here goes:

I have couple '80s Peavey basses that need some fretboard work, particularly my fretless Foundation. The Owner's Manual lists the radius as 8" and of course the only radius blocks I can find are for You-Know-Who's 7-1/4" and 9-1/2" radii.

Surely someone out there has worked on 8" radius fingerboards - who sells 8" radius blocks? Thanks!
 
#2
I make custom radius blocks as needed on a CNC, this is the parametric model I made that will give me any dimensions I want. Fretboard radius sanding block|Autodesk Online Gallery

Before that I did everything with a flat block, did tons of fret jobs that way. So you don't really need the radius block but it's nice. The 9.5 inch will work well, anything will as long as it bigger than the radius you want. The 7.25 would cause problems at the edges.
 
#4
TrustRod said:
I make custom radius blocks as needed on a CNC, this is the parametric model I made that will give me any dimensions I want. Fretboard radius sanding block|Autodesk Online Gallery

Before that I did everything with a flat block, did tons of fret jobs that way. So you don't really need the radius block but it's nice. The 9.5 inch will work well, anything will as long as it bigger than the radius you want. The 7.25 would cause problems at the edges.
Click to expand...

Thanks for sharing the CNC model, TrustRod. I'm trying to get my son to make a few on his company's CNC machine.
 
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#5
+1 on the flat block.

If the board is already 8” radius you could probably just buy a 7.25” wooden block. Put some sandpaper on the fretboard with the grit side up and run the 7.25” block back and forth until it gets sanded to match the 8” radius. The difference is marginal so it wouldn’t take long.

Then you have your own “custom” 8” radius block.

Kinda the same concept when you have to make the bottom of a nut match the radius of the board.
 
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#6
In my (admittedly limited) experience, you really want to use a flat sanding block on a fretless and just make the string paths true, then blend it to a curve. I wouldn't want to use a radius block and I wouldn't worry about not having one. Even if the fretboard started life with a fixed radius, a fretless really needs to be compound in order to play well with good action.
 
#7
Jisch said:
I agree with the above, if your fretboard already has a radius on it, you just need to make sure your string paths are flat - no need to re-do the radius. You can do that with a flat sanding block (or a larger radius block as mentioned above).
Click to expand...

Thanks, Jisch. A question on technique - I saw on YouTube someone said to make the neck dead flat with the truss rod before any leveling (frets or fretless). Would you agree? Any tips?
 
#9
Post Script: Based on the comments regarding a flat beam versus radius blocks, I broke down and ordered a flat beam from Fret Guru - it arrives tomorrow. Thanks to Jisch, TrustRod, dwizum and thisSNsucks for your insights!
 
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