New Lathe Tool Sharpening Jigs
By Steve Fritzinger
Sharp tools are essential for woodworking. No one knows that better than a wood turner. When a 40-tooth table saw blade rips through an 8’ sheet of plywood, each tooth removes less than 3” of material. When a turner roughs a 5” diameter piece down to 3”, her gouge must cut through hundreds of yards of material. A finishing cut to remove a mere 1/16” from the piece exposes the tiny cutting surface on her skew to almost 1,000 yards of material. Turning a single bowl or table leg inflicts miles of wear on tools.
A sharp chisel means the difference between plowing through a piece, leaving catches and tool marks in your wake, or effortlessly bringing out the form you desire with a finish that might not even need sanding. While a table saw blade might need sharpening every few months, a good turner sharpens multiple times per session.
All that sharpening causes many problems in a shared shop like Nova Labs. Inconsistent or sloppy sharpening turns what should be a razor edge with a flat bevel into a rounded or irregular mess. Regrinding tools to repair their edge greatly reduces tool life. While many tools are designed to use a primary and secondary bevel, having a tertiary, quaternary, quinary, and more–ary bevels is bad. Adjusting the sharpening station by hand is a complicated process involving a Sharpie marker and a fair amount of skill. This simultaneously discourages the right kind of sharpening while encouraging destructive practices.
In late 2020, lathe stewards Amy Rothberg and Ken Poirier came up with a solution to the sharpening conundrum. They envisioned a set of simple jigs that would make adjusting the sharpening station for skews, roughing gouges, scrapers and parting tools as easy as holding a jig up to the grinding wheel and tightening the tool platform screws. They proved the concept with a simple cardboard prototype. They then recruited Steve Fritzinger to adapt the prototype into a finished product.
“Overkill” Fritzinger’s first idea was to create a spreadsheet that took the grinder’s geometry and desired bevel angle as inputs and automatically generated the needed jig design. While easy in theory, this proved too much for Steve. After months of working on this method, including creating a fully articulated, 3D model of the grinder in Fusion 360, Steve hit on a much simpler idea. He asked Amy and Ken to setup the grinder for one type of chisel, held a plywood template up to the wheel and drew the jig around it and tool platform.
They repeated the procedure with the other types of tools and in less than an hour, they had templates for all four chisel types. Steve converted those designs into DXF files and laser cut the jigs from scrap plywood.
After one round of tweaking and tuning, those jigs are ready for Lathe Lane. They are now attached to the sharpening station and ready for use. Hopefully, they will help Nova Labs members become better turners while increasing the working life of our tools.
Ken Poirier is teaching How to Sharpen Lathe Turning Tools Sunday May 2nd, 2021. Register on the Nova Labs portal.