Endmills, ground to a drawing

21 September 2026. A special endmill enquiry is a drawing and a conversation. A diameter and a flute count are the easy part, and behind them sit the flute section, the helix, the core, the gash and the relief on every end tooth, the coating, the grade and which rod in the rack it can actually be ground from. Most shops work that out by hand, one tool at a time.

The tool on the screen is the real tool

• The flute sections are measured, not drawn. Forty six ground solid carbide tools were analysed face by face; the eighteen helically fluted ones gave one canonical section per flute count. A flute count nobody measured uses the blend of them, scaled to the core and the land you ask for.
• The run out is a wheel position, not a fade. It is the full depth flute section revolved about the axis the grinding wheel sat on when it left the work, and both measured wheel positions are offered. A flute too wide for the wheel to swing out of is ground out on a straight retract instead, and the cutting list says so.
• The end teeth are exact planes: the gash face through the cutting edge and the tip centre, the pocket ahead of each tooth, the flat land and the relief behind each end edge. Every one of them is a setting here because every one of them is a wheel setting on the grinder.
• Square, corner radius, ball and chamfer ends, one to fourteen flutes, any helix to sixty five degrees, a margin and a primary relief, a necked reach, a Weldon flat or a whistle notch, and through coolant holes that follow the flutes.

The coating shows

• Pick a coating and the model shows it: over the flutes and however far past them you set, in the colour the trade names for it, with the shank left bright.
• That is not decoration. A coating puts four to ten micrometres on a diameter against an h6 shank band of eight to thirteen, and a shrink fit holder has no clamping range to absorb it, which is why a shank is normally left bare.
• Colour is an appearance and never an identification. A coating is known from what was ordered and what the coater ran.

The blank comes out of your own rack

• The rod is matched on the largest ground diameter anywhere on the tool, not on the cutting diameter, so a necked or stepped special buys a blank that can actually make it.
• Ground h6 and as sintered are two products and the quote knows it: an as sintered blank carries its grinding allowance. The length is the finished length plus the one millimetre facing allowance a cut to length blank carries, plus whatever you set for the cut off.
• Grades are named by grain and binder, the way a rod line is specified, and are never cross referenced between producers. If nothing in your stock covers the job it says so rather than quietly pricing a blank you do not hold.
• The grinding is priced pass by pass and scales with the length of cut and the helix, because the wheel path is the length of cut over the cosine of the helix angle and fluting is the longest operation on the tool.

A profile you upload becomes a form cutter

• Upload a DXF or draw the axial section of a form and it is scaled uniformly onto the cutting diameter, so an angle drawn at forty five degrees stays at forty five degrees. An inch drawing is converted and says it was.
• The flutes then follow the form: every station is the same section scaled to the radius the tool has there, so the flute keeps its share of the local section instead of cutting through the core where the form narrows.
• The tightest internal radius in the form is measured and flagged, because a concave radius can only be ground by a wheel edge smaller than it.

What it will not tell you

• No cutting data. A speed, a feed, a chip load, a depth of cut and a tool life depend on the machine, the material and the setup, and none of them is derivable from the geometry.
• Drills, reamers and countersinks share the parameter set and are not built yet.
• Every rate it ships with is a modelled illustrative default. Set them against your own cell in Rates and stock before a quote leaves the building.