The key is to figure out the size of the Swing Over Bed of your lathe machine
Understanding Lathe Swing-Over Bed Sizes
Following the diagrams of the two figures below:
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Figure 1
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Figure 2
You can either measure and calculate it or retrieve the size of the swing from the lathe's manual.
Then select the Quick Change Tool Post(Set) based on the Lathe Swing-Over Bed Size.
Swing-Over Bed Size Chart
Lathe Swing-Over Bed Sizes | Corresponding QCTP Set | QCTP Only |
6-9 inches | OXA ---> 0251-0000 | OXA ---> 0250-0000 |
9-12 inches | AXA ---> 0251-0100, 0251-0111, 0251-0118, 0251-0119 | AXA ---> 0250-0100, 0250-0111 |
10-15 inches | BXA ---> 0251-0200, 0251-0222, 0251-0228, 0251-0229 | BXA ---> 0250-0200, 0250-0222 |
13-18 inches | CXA ---> 0251-0300, 0251-0333, 0251-0338 | CXA ---> 0250-0300, 0250-0333 |
14-20 inches | CA---> 0251-0400, 0251-0444 | CA---> 0250-0400, 0250-0444 |