I looked at a Reed vise advertised on Craigs List this past weekend, mostly because it was right down the street. One full turn of the handle before there was any movement on the jaw. Shot.
Ted, this condition that seems to be excessive thread lash is very seldom an indicator of worn threads on the mainscrew (leadscrew) or the vise nut. If you flip such a vise upside down, you can easily see what causes this condition. There is typically a part on the mainscrew variously called a collar or a horse-shoe clip. This part retains the mainscrew in the vise moveable jaw/slide casting. It is usually installed in a groove on an un-threaded portion of the mainscrew. When you turn the vise handle clockwise to tighten down on something, the large shoulder at the handle end of the screw pushes the moveable jaw closed. When you turn the handle counter-clockwise to open the vise, this collar or the horse-shoe clip, and possibly a washer or bushing, bears on the inside of the moveable casting. If there is too much clearance, it can take perhaps a full turn before the jaw moves in the opposite direction.
In most cases, it was probably like that from the time it was new. Different vise manufacturers use slightly differing designs. But usually a little study will tell you what modifications you need to do if this extra motion is a problem.
A lot of vises do get serious abuse during their lives. It seems to happen a lot in industrial plants where heavy handed employees don't know, or just don't care, because they didn't fork out the money to buy it. Here's a short article showing some of the common ways vises end up broken. I've admitted to beating one decent vise to death. I was bending a piece of steel bar with a sledge hammer. I had been heating it red hot with an oxy-acetylene torch, but let it cool a bit too much, and wailed a bit too hard with the sledge hammer. There was no warning... it just broke.
https://mivise.com/not-break-vise/
