INCH THREAD
The inch threading gear chart is illustrated in
Figure 46
. The layout is listed below to help identify the
gears needed for cutting threads with inch pitches. The chart lists pitches in threads per inch.
Figure 46
. Rates given in millimetres and inches.
1.
The column of numbers to the right of D represent the number of teeth on gears used in position D.
2.
The numbers below A represent the number of teeth on gears used in position A. In this case 25 or 75
teeth.
3.
Field of possible thread pitches.
4.
The gear used in position B and C will always be the 125/127 combination gear. The 125 tooth gear
will need to be oriented so it is in mesh with the gear in the A position.
The Model B is capable of cutting many standard inch and metric threads. Follow the procedures listed in
Changing Gears
in the previous section and change the gears according to the chart for the thread
desired.
Figures 47 – 50
show the order the gears should be installed. This example shows gearing for
cutting a 10 or 20 thread per inch (tpi) screw thread. (The
Feed Rate Lever
set to the I position will allow
10 TPI. When the lever is set to the II position, 20 TPI will be cut.)
Figure 47
. 75 tooth gear installed at “A”.
Chester UK Model B
29
