Andy F. commented about the surprisingly light weight of my recently acquired 9" Mystery Vise.
We exchanged thoughts and ideas and compared verbally a 'typical' 8" bench vise that weighs around 300#
And the Mystery Vise is about 175#.
So I made some measurements.
The dynamic on the Mystery Vise is 20.5" without the mainscrew hub. So from the mainscrew thrust surface to the end of the slide.
The dynamic on the Reed 208 is 27.5" long, again from mainscrew thrust surface to the end of the slide.
The depth from the top of a jaw to the top of the slide is an inch shorter on the Mystery Vise. So both the jaw towers on the beefy Reed are an inch taller. The taller jaws mean there is more leverage to bend and possibly break the jaw tower off of the slide, so more metal is needed to provide strength.
The width of the static and the dynamic jaw tower are both the same at 6", and the Mystery vise is also 6" wide.
The comparision of the mainscrews, hubs and retainers is interesting. Both have hubs [meatball] that are 3.25" diameter.
Both mainscrews are 1.355" diameter. [slightly less than 1-3/8" diameter]
The retaining collar for the reed is 1.25" long and uses one set screw to anchor the collar to the mainscrew.
The Mystery Vise's retaining collar is 2.5" long, and uses THREE set screws to anchor the collar to the mainscrew.
The outside diameter of the Reed retaining collar is 3/8" larger in diameter than the Mystery vise's collar.
The casting of the slide on the Reed is able to allow the retaining collar to easily be dropped down over the mainscrew, there is plenty of room around the collar.
On the Mystery vise, the collar can barely fit through the opening for the mainscrew in the slide. So the sides of the slide are noticably thicker than the Reed's.
The machined surfaces that support the dynamic jaw and slide are 12.5" long, with some gaps in the Reed, The Mystery vise's supports are full length in contact with the slide and are 14" long..
The mainscrew nut on the Reed is 4" long [threaded part]. On the Mystery Vise the threaded portion of the nut is 6" long..
So some 'conclusions': The Mystery vise while it does have 8.75" wide jaws, it was made for a different type of work than the massive Reed. Yet the Mystery vise has several very heavy duty features that exceed the Reed's.
The very beefy mainscrew and it's extra long threaded nut and long slide support suggest a job application requiring a lot of opening and closing the vise, So the extra meat at the high wear points.
The depth from the jaw to the slide being shorter on the Mystery vise suggests that a *********** was not needed, and this allowed using less supporting iron in the jaw towers.
The Reed opens much wider, around 16". The Mystery Vise opens 10". Again, it seems that the Mystery vise was made for a job needing a wide jaw, but not as deep a throat or as wide an opening.
There is no doubt that the three mounting ears on the static base are the largest I've ever seen.
I still have not found a single number, letter, or stamping on the Mystery vise..
I'm putting together a plan for repairing the jaw supports and making new jaws. More later.

Pierce A