My CNC machines have limited work envelopes. As a result I have modified a number of screwless vises to maximize use of the work envelope. 3 are 6.6 x 11.8 and only after I reconfigured the software. I long ago figured out a modified 5 inch vise with jaws machined back or other modifications worked best for y, and a 6 inch was an "okay compromise for X. In fact a pair of 5 screwless vises modified to match would give the most working envelope. I only have one five inch screwless vise. I've been using six inch on the other two machines.
Technically they are 4.72 (120mm) wide by 5.91 (150mm) jaw opening. In the past I have just machined away part of the jaws, to provide wide opening, and small step jaw, and clearance for through holes in mold plates. I think this time I'll do it differently. Machine a grove on the flat tops of the jaws to add a secondary jaw. Z height is limited on the smaller machines, but since I am almost exclusively machining plate no thicker than an inch it shouldn't be an issue to raise the work piece a little. If I do have to work on somethign outside my normal scope I am charging extra for it anyway, so taking down the default setup is not a big deal.
I have been wanting some screwless vises in this size class for a while, but they all seem to be over priced compared to smaller and even some bigger options. A while back I found some from Tormach of all places. I put six of them in my shopping cart and saw I qualified for free basic shipping. I didn't want to spend the time, and I forgot about them. Yesterday I was looking up something else on the Tormach website and saw they were still in my shopping cart, still a great price, and still free shipping. I figured I better get them while they were still available.
Now I might have some use for that surface grinder Jim was talking about, or maybe I'll just mill them and call it good enough.
Anyway, the main point of this post was to let you guys know about them if any of you have a use.