Precision luthier tools. Made in Virginia, USA. Lifetime Warranty.

Skip to product information
1 of 2
Luthier Tools > Radius Sanding Block Set, 3-Block (2.75″ Wide)

3 Radius Sanding Block Set (2.75″ Wide)

3 Radius Sanding Block Set (2.75″ Wide)

Regular price $30.00
Regular price Sale price $30.00
Sale Sold out
$30.00
Lifetime Warranty  ·  Made in Virginia, USA  ·  Ships in 3-4 business days

2.75″ wide. 3 blocks. Your choice of radii.

A set of three radius sanding blocks for setting fretboard profile during a new build, restoring the radius during a refret, or leveling frets to the board's existing curve. Standard 2.75″ width fits regular six-string and most narrow-spec bass fretboards.

Radius & Length

Lengths

  • 4″ for spot work
  • 8″ and 10″ for general fretboard sanding

Radii

  • Imperial: 7.25″–30″
  • Metric: 390mm–430mm
  • Flat
  • Custom: email us for a radius we don't list, no extra charge

Sandpaper

Sized for 2.75″ wide adhesive-backed sandpaper. 3M Stikit Gold rolls from StewMac fit clean with no overhang.

Material

3D-printed in PLA. Reasoning is in Why We Use PLA. Covered by our lifetime warranty if any block ever fails.

Working on a full build?

The Fretboard Radius Jig establishes the radius with a router in under ten minutes. The blocks then smooth the board after, a couple of minutes per grit. Many builders run both: jig for stock removal, blocks for finishing.

Want different quantities or a single block?

Buy single blocks at Radius Sanding Block (2.75″ Wide).

Specs

Width 2.75″
Length
  • 4″
  • 8″
  • 10″
Quantity 3 blocks
Radius
  • Imperial: 7.25″–30″
  • Metric: 390mm–430mm
  • Flat
  • Custom
Material PLA
View full details

Collapsible content

How to Use

At a glance

  • Apply 2.75" adhesive-backed sandpaper to the curved face. Trim flush.
  • Sand lengthwise along the fretboard with even pressure. Do not twist.
  • Step up through grits as the surface evens out.

Step-by-step

  1. Apply sandpaper. Press 2.75" adhesive-backed sandpaper firmly onto the curved face. Trim any overhang flush with the block's edges so it doesn't catch on the fretboard.
  2. Mark witness lines. Scribble a crosshatch pattern across the fretboard with a soft pencil. As you sand, the pencil disappears from the high spots first and remains in the low spots. When the crosshatch is gone everywhere, the block has reached the whole surface.
  3. Choose your starting grit. 80–120 for new fretboards or refret prep where there's wood to remove. 220 if the board is already close, including a board coming off the Fretboard Radius Jig, and you're cleaning it up. 320, 400, and higher for finishing.
  4. Sand lengthwise with even pressure. Hold the block flat to the fretboard and stroke along the length of the fretboard, nut to heel and back. Keep the block square. Do not twist or rock side-to-side. Twisting changes the radius.
  5. Re-mark and check often. Refresh the crosshatch between grits and confirm the block is touching the full surface before stepping up.

Notes

  • Verify the radius at every grit with a radius gauge. Twisting or uneven pressure can shift the profile, and catching it early means a few extra strokes instead of starting over.
  • Clean the fretboard between grits with a vacuum, brush, or compressed air. Leftover coarse grit will gouge the surface when you step up to a finer paper.
  • The 4" length is best for spot leveling and smaller corrections. The 8" and 10" cover the full board faster with a more consistent stroke.
  • Change or clean paper often. Loaded paper cuts unevenly and inefficiently.