The top is 32" x 54". I glued it up using 3/4" S3S boards sized using a ripping blade for my table saw and biscuits. It wasn't perfectly flat, but good enough, so I started in on sanding. I have a Makita 9403 4" x 24" handheld belt sander, and I sanded the top with new 80, 120, 150, and 240 grit belts. I sanded pretty much with the grain, but I rotated the sander a little as I was moving along as birdseye is flatsawn and can have quite a bit of wavy grain, depending on the piece. I put pencil lines across the piece between each grit as a way to verify that I was sanding it evenly and thoroughly.
As I was progressing through the grits, I noticed a little bit of waviness – ridges in the texture of the surface. They weren't sharp, like I'd left the sander running for too long in one spot and the edge of the belt had dug in, but fairly smooth, like a series of gentle hills and valleys. What was interesting was that they didn't necessarily follow features of the grain. For example, when sanding soft "SPF" woods like yellow pine, the darker growth rings are more dense than the lighter wood in between, and if you're not careful you can get ring texturing in the surface when sanding. My ridges are not like that – they follow the direction of the grain, but cross individual grain lines without changing.
I'd like to rescue this if I can before I start the finishing process. Unfortunately, I don't have access to a wide belt sander (if you know of any in the Boston, MA area, please let me know!), so I'll have to stick with what I have available, which is the Makita belt sander, a DeWalt 5" random orbit sander, a decent low-angle block plane, and a lousy knockoff bench plane. With such highly-figured wood, the thought of planing doesn't make me very happy, so I'll have to figure it out with sanding.
Would sanding against the grain with 240 and then with it again have any effect, or will it just create unnecessary scratches? What about cross-grain with a rougher grit, then smoothing again? I'd like to ultimately go up to 320 or 400, then perhaps (or instead) do a few passes with a good cabinet scraper to really "pop" the figure before finishing. Would the scraper be the best option for flattening the top as well?
Any and all suggestions are welcome.