What is the fine-grained topic of the following text: Discussed are attachments for cutting screws of large lead without breaking teeth off the change gears, a special lead-screw for cutting coarse pitches, methods of cutting threads so that the pitch is slightly greater or less than standard (to allow for heat treat shrinkage), use of translating gears for cutting metric pitches, designs of quick threading attachments, thread chasing attachments, devices for cutting tapered threads and more. Only return the topic.
Machinery Attachments and Methods for Cutting and Modifying Threads