Also, would using a thicker piece of plywood help me keep a more level surface once it's screwed into the stand itself? a piece of 3/4 Maple Plywood for example. In hind sight, what i should have done is taken the planks and ran them through a table saw to flatten the 1.5" side. I was considering making the stand shorter and if i do it gives me the perfect chance to run them along a table saw to get that nice flat plane. Now to find a table saw...![]()
Don't confuse level with flat (aka, coplanar).
Level happens with shims under the stand to correct issues with the floor.
Flat is built into the construction of the stand. If the top frame is coplanar anything you attach to it should also be coplanar. That's where the sanding Rocket talked about above happens. You could also use a hand plane to take off high spots. It is also possible to fill in low spots on the frame with shims. Both of these corrective actions are to correct 2x material that is not straight.
I'm not sure where you are going with the table saw talk. It is possible to get a straight side on a 2x with a table saw. It's not as trivial as running it thru the saw. In general, boards are given a straight edge with a jointer.