I just completed machining a 6" riser for my machine also. I found the below listed spec for the block on the Internet. I would like to give credit to the person who listed them but donot know their name.I plan to install a 5" riser block on my Enco knee mill. The mill is in a corner where I can't easily get to it with my hydraulic engine hoist. I plan to fabricate the device shown below, and let the knee crank raise the head so I can install the riser. An advantage would be that I would be able to keep the head raised for whatever time it takes to do measurements, complete the riser block, and install it without having to worry about it hanging from lifting straps for a day or two.
One of the assemblies shown would be on each side of the table, sufficiently far apart to span the head. The two sides would be bolted to t-nuts in the table, and bolted together via a cradle shaped plate in the front and a flat cross piece at the rear.
I would welcome any opinions on whether this will work, or put too much strain on the knee screw. I don't anticipate having to adjust either the X or Y axes with the load in place. The lift distance appears more than adequate.
6" Diameter Material
4 1/2 " Bolt Circle (I drilled mine .500 holes) 3 Holes
3.125 x .700 Deep Recess
3.115 x .625 Long Spigot
Choose your material carefully, I bought a piece of hot rolled and it was very hard. It made a nice looking block but it was all my 9" SB wanted. I lifted the head with chain hoist from ceiling. Good luck.