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F5-L Mandolin Binding Repair

Repairing damaged binding and purfling points and replacing mismatched ivoroid point caps on an F5 mandolin — with 3D-scanned, CNC-milled cast-resin binding, color-matched and tinted to disappear.

James Roadman The Looth Group

June 1, 2026 · 1 min read

Folk, Bluegrass, Irish, Old Time Instruments 3d scan binding repair cnc fusion 360 liquid binding lutherie mandolin restoration

This F5 mandolin came in the shop with damaged points and previously replaced point caps. The replacement caps were oversize and an ivoroid material that didn’t match the binding. My job was to repair the damaged points and replace the caps. I recently purchased a Creality Raptor scanner and this seemed like a great opportunity to start using it for repairs. The scanner, in conjunction with a CNC machine router or mill, gives the ability to create irregular shapes that fit the damaged area like a puzzle piece. This allows repairs without removing additional materials.

The damage

Cracked, mismatched ivoroid point cap on an F5 mandolin’s body binding. — An old repair had fitted oversized ivoroid point caps that didn’t match the original binding — and they had cracked at the ends.

Damaged binding and purfling at an F5 mandolin body point. — The binding and purfling were damaged at the points.

Mismatched ivoroid replacement cap meeting a damaged binding point. — The ivoroid cap replacement where it meets the damaged binding point.

Scanning & modeling

Structured-light 3D scan mesh of a damaged mandolin binding point. — A Raptor 3D scan of one of the damaged points, captured as mesh so the exact geometry can be rebuilt.

3D scan of an F5 mandolin ivoroid point cap after removal. — A scan of one of the point caps after removal.

A damaged binding point on the F5 mandolin body. — One of the damaged binding points.

Here are some examples of the scans used to create the replacement pieces.

Scanned point geometry set into stock in Fusion 360 CAM. — The scan set into a block of virtual stock in Fusion 360 — the captured surface becomes the shape to match, and the software generates the cutting toolpaths.

These scans were then edited to remove extraneous features and imported into Fusion to create the toolpaths for machining.

Machining the replacements

Cream cast-resin blank used to mill replacement binding and point caps. — Cream cast resin, used to make the replacement pieces.

CNC-machined cast-resin replacement piece matching the original binding. — CNC-machined resin, cut to match the damaged binding.

Finished CNC-milled cast-resin point cap replacement. — A finished replacement piece — its CNC-milled contour matches the existing binding so it drops in like a puzzle piece.

Fusion 360 CAD model of the replacement binding and point cap. — The modeled replacement in Fusion 360: binding and point cap as a single solid, ready to machine.

End mill cutting a cast-resin binding replacement on a CNC router. — Cutting a replacement from cast-resin stock on the CNC, taped to a sacrificial board.

Installation

Dry-fitting a machined replacement point cap before gluing. — Test-fitting a machined replacement at the point before glue-up.

Repaired binding point with excess replacement material trimmed away. — The binding point with the majority of the excess material removed.

Refining a repaired mandolin point and starting to color match. — Refining the point and beginning to color match.

Repaired point tinted to match the original ivoroid binding. — The final point, tinted to match the original binding.

Adding tinted finish to blend the binding repair into the original. — Adding color to match the original finish.

Finishing & the final result

Repaired point masked with tape and foil for finishing. — Masking off the repair for finish and color work.

I used CA glue for the binding points and epoxy for the caps. After getting everything installed it was time to do the final shaping, cleanup, and finish touch up. This was a combination of gluboost finish, tints, Doug Proper’s liquid binding recipe, and tinted lacquer.

Finished upper point cap and binding point on the F5 mandolin. — Finished upper point cap and binding point.

Finished lower point cap, color-matched to the original binding. — Finished lower point cap.

Repaired lower binding point, backside view. — The repaired lower binding point (backside).

Repaired F5 mandolin binding point, frontside, blended into the original finish. — The repaired binding point (frontside).