Charts, formulae, and general information on these pages should guide you to choose the correct end mills, tapered end mills, and cutters.
   Our standard end mills are designed for side milling, or interpolating around the inside of a cavity.  Our 17° and 28° right-hand spiral end mills are relatively fast spirals for use as reamers on some materials.  If reaming a hole in tough materials, they may chatter and grab into the side wall.   In these instances, for reaming a blind hole, we prefer to make special end mills with a slow 12°right-hand spiral.  If you are reaming a large enough through-hole, a left-hand spiral end mill would work good, because the chips travel downward;  whereas a right hand spiral will bring the chips out of the top.
   All end mills, tapered end mills, and cutting tools are breakable, but a judicious selection will minimize breakage.  The greater the length of the end mill compared to its diameter, the more fragile it is.  Use an end mill with as short a flute as possible.  Short end mills cut fast and free, lessening the hazard of breakage.  When long, slender end mills and tapered end mills must be used, a light cut is called for.
   Because of the varying diameters of Conical tapered end mills, spindle speed and feed rate cannot be accurately recommended.  Generally, you are right to run Conical tapered end mills at the highest possible speed that does not produce heat-discolored chips.  Feed the end mill slowly enough to let the cutter do the cutting.  Feeding too fast can cause broken tips and chipped flutes.   When you use coolant or air on the end mill, you can increase spindle and feed rates.
   All high speed steel Conical end mills are produced from premium grade,  high speed steels, heat treated to a high Rockwell, for shock and abrasion resistance.   Carbide material is premium micro-grain carbide.
   Taper angles remain constant to tolerances of +/-.001" per inch of flute, regardless of the end mill's diameter or length, even after resharpening.  Tip tolerances are held at +/- .002" (.001" for straight end mills).  Shank tolerances are -.0002" to .0005".  Constant helixes of right hand spirals range between 28° for smaller end mills, 25° for larger and steeper tapers.  Constant helixes of left hand spirals range between 15° and 18°.
   Conical Tool Company has always welcomed the chance to produce end mills or tapered end mills to your own specifications. We have over-runs on many special end mills produced for other companies.  Check with us early, we may have your answer in our stock room.