A sample
of the complete range of rack type gear cutting tools we manufacture
at PRECISION TOOLS. We make cutters to produce many types of gears
and racks, or specials to designs and samples.
| Involute
Gear Cutters
Selection of Involute Gear Milling Cutters for a given diametrical
pitch and number of teeth.
When
gear teeth are cut by using formed milling cutters, the cutter
must be selected to suit both the pitch and the number of
teeth, because the shapes of the tooth spaces vary according
to the number of teeth. For instance, the tooth spaces of
a small pinion are not of the same shape as the spaces of
a large gear of equal pitch. Theoretically, there should be
a different formed cutter for every tooth number, but such
refinement is unecessary in practice. |
 |
The
involute formed cutters commonly used are made in series of
eight cutters for each diametrical pitch (see accompanying table).
The shape of each cutter in this series is correct for a certain
number of teeth only, but it can be used for other numbers within
the limits given. For instance, a No. 6 cutter may be used for
gears having from 17 to 20 teeth, but the tooth outline is correct
only for 17 teeth or the lowest number in the range, which is
also true of the other cutters listed. When this cutter is used
for a gear, say, 19 teeth, too much material is removed from
the upper surfaces of the teeth, although the gear meets ordinary
requirements. When greater accuracy of tooth shape is desired
to insure smoother or quieter operation, an intermediate series
of cutters having half-numbers may be used provided the number
of gear teeth is between the number listed for the regular cutters
(see table).
Involute
gear milling cutters are designed to cut a composite tooth
form, the centre proportion being a true involute while the
top and bottom portions are cycloidal. The composite form
is necessary to prevent tooth interference when milled mating
gears are meshed with each other.
A full range of gear type milling cutters are made at PRECISION
TOOLS, including involute, spocket and rack. We manufacture
and stock a comprehensive range of gear cutting tools and
also make tools to customers' special requirements or designs.
A regrind service is also available.
|
Regular
Cutters
| Number of cutter |
Will cut gears
from |
|
Number of cutter |
Will cut gears
from |
| 1 |
135 teeth to a rack |
|
5 |
21 to 25 teeth |
| 2 |
55 to 134 teeth |
|
6 |
17 to 20 teeth |
| 3 |
35 to 54 teeth |
|
7 |
14 to 16 teeth |
| 4 |
26 to 34 teeth |
|
8 |
12 to 13 teeth |
Intermediate
Series Cutters
The
cutters listed below, having half-numbers, may be used when greater
accuracy of tooth shape is essential in cases where the number of
teeth is between the numbers for which regular cutters are intended.
| Number of cutter |
Will cut gears
from |
|
Number of cutter |
Will cut gears
from |
| 1 1/2 |
80 to 134 teeth |
|
5 1/2 |
19 to 20 teeth |
| 2 1/2 |
42 to 54 teeth |
|
6 1/2 |
15 to 16 teeth |
| 3 1/2 |
30 to 34 teeth |
|
7 1/2 |
13 teeth |
| 4 1/2 |
23 to 25 teeth |
|
... |
... |
|
