Maintaining T-12 Dimension
On Blades Used In Rake Angle Tools
The full efficiency of Genesee Adjustable Hollow Mills with 12
degree rake angle depends upon the shear action of the blades. The throat
length of the blades must be ground so that when the mill is adjusted to
the finish diameter the blades are the correct distance ahead of center.
The smoothness of the finish depends upon the efficiency of this shearing
action. The blade grinding instructions contained in our catalog and our
T-12 formula are designed to show correct angles and throat lengths for
ordinary work.
Maintaining the proper T-12 dimension on rake angle blades
requires that adjustment of the Hollow Mill to size occur through the
maintenance of the T-12 dimension, NOT
through adjustment of the blades with the ring. Adjustment with the ring
should only be necessary to make the small adjustments necessary to set
the Hollow Mill to size after regrinding.
If the T-12 dimension is too short, the blades will be too far
behind centerline at the cutting diameter, thereby producing chatter
and/or rough finish.
If the T-12 dimension is ground too long, then the blades will
be too far ahead of centerline at the cutting diameter and produce a
tapered part larger at the end of the cut and/or poor finish.
WHEN ORDERING Rake Angle Hollow Mill blades please be sure to
tell us what diameter you will be hollow milling and we will insure that
your blades arrive with the proper T-12 length ground for your job. |