How to eliminate waviness/ridges on 4" belt-sanded desktop?

Question

I'm making a desk for my son using hard birdseye maple as the material for the top. I've never worked with birdseye specifically before, but I've used hard maple in other projects.

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.

Answer 1

At first I tried planing (using test pieces instead of the actual top), with both a pretty well-tuned low-angle block plane

and a cheap Buck Bros. #5 jack plane with a freshly-sharpened blade,

but I haven't had time to tune anything else. The low-angle worked better than the #5, but I had tearout issues with both of them, so I didn't let them near the actual desk top.

I then tried using a card scraper. Once I got a good burnished edge curl on it and figured out how to hold it properly it gave me very good control at removing wood just where I wanted to. However, with the amount of wood it removes with each pass (a very thin shaving, or just dust) and the amount of surface I had to flatten (32" x 54" – 813 mm x 1372 mm), plus a bit of arthritis in my hands, it would have been a daunting task to scrape flat the entire surface.

Then I happened across a Kunz-manufactured version of the #80 scraper plane:

It differs from a card scraper in several ways – the blade is about twice as thick, approximately 1/16" (0.06" or 1.53 mm), the curl is burnished from a 45° angled edge instead of a flat 90° one, the depth of cut can be adjusted somewhat by raising and lowering the blade in the housing, and importantly (for me, at least) the tool is comfortable to use for long periods of time. It requires the same amount of force pushing away from your body, but the wear and tear on your fingers from forcing the card scraper into a curve is completely eliminated, as the blade is curved by means of a screw in the middle of the body.

Even with an aggressive cut depth, it still took me at least 2-3 hours to get the entire surface to a more-or-less flattened state. After the initial scraping, I drew pencil lines over the surface and used a random orbit sander with 120 grit sandpaper to get an even finish and find any remaining high/low spots. I came back with the scraper to address them, and after a couple rounds it's looking pretty good!