Thread Box
From DT Online
Thread Boxes are the equivalent of Dies but are used for cutting screw threads in wood.
They are usually supplied with two matching wood taps: one starter tap and one bottom tap to produce the equivalent internal thread.
Note:
Threads are cut most successfully in fine-grained woods (e.g. such as: beech, cherry and pear). Coarser grain timbers, such as pine and oak are unsuitable except for large diameter threads. For best results, soak the wood to be threaded in oil (e.g. linseed, olive or vegetable oil) and wrap it in ‘cling film’ overnight.