"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)
Because: the threads are on very crooked, the top threads on one end are all buggered and do not work, if I cut the ends off there does not appear to be enough threads to reliably hold, especially if, like Jim mentions above, I end up having to rethread or file the top threads to get them to start into the plane's body. The big reason is the first one though, the whole shaft of the screw circles in a crooked circle, due to the threading being crooked, just on the first thread or two. Trying to use pressure to get past a couple threads at the top risks buggering the threads in the plane.
I don't know the age or country of origin ( U.K. or U.S.) for your Stanley planes but some of them have Whitworth threads and that is a difficult thread to find taps or dies for. I saw some one else say get a thread gage, do that , it will help a lot. I am a retired mechanic that has worked on equip from all over the world and have had multiple thread issues over the years, get a thread gages. You could always contact Don W. at WWW.timetestedtools.com ,he might help.
Stanley #55 plane thumb screw with shoulder is 1/4-32 x 1/2"
I've never dealt with VictorNet, but their prices for US-made stuff are surprisingly good. For example they offer a set of US-made #1-#60 HSS taper-length twist bits for $129, while a similar Chicago-Latrobe set goes for over $500. Does anybody have a sense for how much of that represents real differences in materials or finish, as opposed to branding?