The purpose of this paper is to present an approach for the determination of geometry of spur gear tooth root fillet. An equation is developed to determine the point of tangency of involute profile and root fillet on the base circle for a spur gear without undercutting and the point of intersection of root fillet and involute profile above the base circle for an undercut gear. Generation using a hob or rack type cutter with protuberance (increase in tooth thickness at the tip of the hob tooth) is also discussed.

1.
Colbourne, J. R., 1987, The Geometry of Involute Gears, Springer-Verlag, Berlin.
2.
Merritt, H. E., 1971, Gear Engineering, Pitman, London.
3.
Pedrero
,
J. I.
,
Rueda
,
A.
, and
Fuentes
,
A.
,
1999
, “
Determination of the ISO Tooth Form Factor for Involute Spur and Helical Gears
,”
Mech. Mach. Theory
,
34
, pp.
89
103
.
4.
Mitchiner
,
R. G.
, and
Mabie
,
H. H.
,
1982
, “
The Determination of the Lewis Form Factor and the AGMA Geometry Factor J for External Spur Gear Teeth
,”
ASME J. Mech. Des.
,
104
, pp.
148
158
.
5.
Mitchiner
,
R. G.
,
Mabie
,
H. H.
, and
Moosavi-Rad
,
H.
,
1983
, “
The Undercutting of Hobbed Spur Gear Teeth
,”
Trans. Autom.
,
105
, pp.
122
128
.
6.
Xiaogen
,
Su
, and
Houser
,
D. R.
,
2000
, “
Characteristics of Trochoids and Their Application to Determining Gear Teeth Fillet Shapes
,”
Mech. Mach. Theory
,
35
, pp.
291
304
.
7.
Salamoun
,
C.
, and
Suchy
,
M.
,
1973
, “
Computation of Helical or Spur Gear Fillets
,”
Mech. Mach. Theory
,
8
, pp.
305
323
.
8.
Litvin, F. L., 1994, Gear Geometry and Applied Theory, Prentice Hall Inc., New Jersey.
9.
Buckingham, E., 1963, Analytical Mechanics of Gears, Dower, New York.
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