slow-poke
Ultra Member
Definitely more than 3", 3.125" is in all likelihood what it is. Well looks like I have another project to add to the list. I will also keep my eye on eBay.Well, Glacern lists 3.125" between holes for their 5" if you measured 3.1" something that seems to confirm. https://www.glacern.com/gsv_550
Same for the Shars 550V - they list 3.125" between the holes https://www.shars.com/5-550v-cnc-milling-machine-vise-0-0004-1 (pretty sure this is a copy of the Glacern who copied someone else...)
but - Shars also has some vises that look alot more like the one you show and they have a far less definitive statement that the holes are 2.99" apart (probably a conversion from 76mm)
If you want hard jaws, most available sets will cost you more than that vise cost new (Glacern are $119 US). I recommend just using some aluminum jaws on it. Make them yourself and be done.
Thanks.