Sherline Threads

Some notes on the Sherline threading attachment, and the list of all possible thread combinations:

This is a list of various threading possibilities on the Sherline lathe, regardless of how common the thread is. Note that there are some "common" threads the Sherline is incapable of, such as the 11.5 tpi on USA garden-hose connections, or 27 tpi (lamps; pipe thread). However, you can get close, and it may or may not be close enough. For example, 26.988 tpi and 11.579 (11.538 is a bit closer but requires a B=50 configuration which is hard to set up; see below). Otherwise you'd need a 23-tooth gear (for 11.5) or a 27-tooth gear, neither available from Sherline (you could make one!).

Very coarse threads may be difficult to machine because you are gearing "up" from the crank handle. This makes it difficult to supply even torque since one turn of the handle results in 4 turns of the leadscrew at 5tpi, for example.

Many of the listed combinations may be difficult or impossible. If you are attempting a thread in the Sherline guide's table, by all means try their setup first. This list may show several possible ways to accomplish it; some may work and some may be impossible entirely. The program was thorough, not necessarily coming up with possible configurations.

The list assumes you have the optional 35-tooth gear. If not, then hopefully some other combination will yield what you need.
The list does not show what idler gears you should use because their actual tooth counts do not matter. Use what will fit, from whatever gears are left over.
The list assumes you have as many of a size of gear as needed. But the standard kit comes with only one of each gear size (except for two of the 20-tooth coarse gears and two of the 100-tooth fine gears).
The Sherline guide lists a 50-tooth "B" gear but does not exactly say how to accomplish this. Apparently you need to press out the hub from the 100-tooth gear and press it into the 50. This is a real pain, to be avoided if possible. An alternative would be to buy an extra gear and hub.

Unfortunately, the program generates the list in order of gearing, not in TPI order. The lists offered here have been re-sorted into TPI order for convenience (the usual question is "what gear settings should I use to obtain xx TPI?", not "given this gear setting, what TPI would result?").