Slotting Cutters: what Claude and GPT would buy
Two AI models chose on their own, with no web access. Nobody tested these products: this is what each one says, and how to check it.
Claude and GPT choose the same product: Harvey Tool Keyseat Cutters
In Industrial & Scientific, Claude and GPT choose the same brand in 52 of 107 categories.
Claude Opus 5.5 · October 28, 2026
Harvey Tool Keyseat Cutters (line)
Solid carbide keyseat cutters from a specialist small-tool maker give rigid, accurate side slots and undercuts on CNC mills across a wide range of diameters, widths and neck reaches.
Not for: Manual-mill users cutting standard Woodruff keyseats in steel on a budget, and anyone needing wide or deep slots that call for an arbor-mounted saw or side-milling cutter.
GPT 6.1 Sol · November 10, 2026
Harvey Tool Keyseat Cutters (line)
Solid carbide construction and numerous cutting-width options make these a strong choice for precision keyways and narrow slots.
Not for: Deep, wide slots or setups lacking rigidity.
Which one fits you
standard Woodruff keyseats, manual mill
Niagara Cutter (brand)
Long-established maker of HSS and cobalt Woodruff keyseat cutters in the standard numbered sizes.
Not for: High-speed CNC work in hard or abrasive materials where carbide pays off.
arbor-mounted HSS slitting saws
Controx (brand)
Specialist maker of HSS and cobalt slitting saws offered in many diameter, width, bore and tooth-pitch combinations.
Not for: Shank-type cutters held in a collet, or users without a matching arbor.
Check before you buy
Where to find Harvey Tool Keyseat Cutters
- Harvey Tool
- MSC Direct
- General Cutting Tools
Shops seen in search results on November 6, 2026. A shop missing here may sell it too. Nothing was checked by a person.
Brands that matter
- Harvey Tool: Carbide keyseat and slitting cutters for precision CNC work.
- Niagara Cutter: HSS and cobalt Woodruff keyseat cutters in standard sizes.
- Controx: HSS slitting saws in many pitches and bores.
- OSG: Broad industrial cutting-tool maker.
- YG-1: Value-oriented industrial cutting tools.
- Dormer Pramet: European industrial tooling.
- Interstate: Budget HSS keyseat cutters and saws.
What to avoid
- Unbranded saws that list no tooth count or bore tolerance.
- Carbide slitting saws on manual mills with leadscrew backlash.
- Running a saw on an arbor with excess runout, which loads only a few teeth and chips them.
- Fine-pitch saws in deep aluminum slots, where chips pack and snap the saw.
Questions
How do I read a Woodruff cutter number like 606?
The last two digits give the diameter in eighths of an inch and the leading digits give the width in thirty-seconds. So 606 is 6/32 wide by 6/8 diameter, matching the Woodruff key of the same number.
Climb or conventional cutting with a slitting saw?
On manual mills with backlash, cut conventional so the saw does not pull the table into the cut. On rigid CNC machines, climb cutting is common and gives better finish and tool life.