07-23-2012, 05:39 AM
I have a 6" Kurt for my RF-45 clone and it works fine on it. It's definitely the largest size that would fit the mill table and still be usable. A 5" would be perfect but I don't think Kurt makes a 5" vise anymore. I also have 4" and 5" Enco import vises. The capacity of the 4" is not always large enough for some projects so I got the 5", which is of lower quality than the 4". I eventually want to get a larger mill so I bought the Kurt 6" when Enco had it on sale with free shipping. YMMV 
Ed
Ed