Wood Slab Flattening Mill - Where to start?

The lowrider is the most stable when it’s at its lowest but 2-3 inches should be fine if you design your machine for that height.

If you want to start surfacing anything more than 4" tall a drop table would be nice.

If it’s a one off project you could use something like my table and leave the center panel out with a table underneath holding the work piece