I'm not a woodworking expert, so I won't advise on your sanding question, but I will recommend getting a piece of glass cut for the tabletop. We did this for the oak end tables in our living room, as well as my grandpa's old ash desk. A local glass company cut them - all I had to do was trace the outlines on heavy paper.

Good luck with your project.

Sand to a fine grain, around 120 or 150 grit. You can sand finer, but from what i have read, you don't get any benefit. Remember to move the sand paper with the grain.

Is the surface solid wood or is there a veneer surface? If it is veneer, even hand sanding can quickly sand through the thin layer. If it is wood, sand to 150, using a sanding block(which can be a piece of flat wood).

Let the stain dry completely, a second coat may take 48 hours to dry. Then lightly sand with 220 grit to smooth the surface for the finish.

Oak has a very coarse grain, and the final finish may not be flat no matter how much you sand. If you've ever seen a vintage piece with a smooth surface, they probably used grain filler. It's a paste that dries clear and invisible but when sanded makes a smooth surface on coarse grained woods. If it's worth your time to make it look nice, you might try it. Apply with a putty knife, remove any excess carefully by rubbing a rag across the grain, let dry and sand to a smooth finish.

I completely understand what Dream Home Finishers is suggesting. A 220 grit absolutely leaves Oak smooth. The ONLY issue with that is you said you were going to add a stain. Staining is a whole different set of rules... If you plan on staining a dark color, and are set on sanding down to a 220 grit, I would have to recommend water-popping the Oak first. 2 Coats of stain are never recommended, especially oil-based stain. The first coat gets absorbed and after that, whatever is left over, just sits on top, and can, very easily, cause issues with your poly. When you sand down to a 220 grit, you're actually closing the pores in the Oak a bit more than you would want to, if you're looking to add a dark stain. Without the added step of water-popping it (in order to re-open the pores to let the stain absorb) your result most likely will be blotchy. If you're going for a light color, it won't matter too too much.

Remember, the desired smoothness of the surface can also be achieved through the finishing coats of polyurethane. If you want to skip the water-popping step, you can finish sanding with a 100-150 grit paper, apply your stain, wait 24 hours, apply first coat of oil poly, wait 24 hours, lightly buff with a used 220 grit by hand, apply 2nd coat of poly and repeat until desired surface texture. In my experience, 3 coats of poly, buffing with 220 in between each, leaves a super-smooth surface that can be achieved even when finishing the sanding with the 100 grit paper. And with the 3 coats of oil-based poly, you won't have to worry about any spills anymore! Spill-away!

I hope this helped, and Good Luck!

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