First is sawing either with a bandsaw or circular saw to get a square "rough sawn" cant. Then jointing and planing to square, flatten, smooth and dimension the surfaces.
Using power tools:
1. A power planer and jointer in combination will square, flatten and dimension the wood. They will leave small, barely perceptible "divots" which will have to be sanded out. This is because of the rotary motion of the cutterhead above the material.
2. You can use a wide belt sander which will sand in the same direction as the grain and use progressively finer grits to remove any machine marks.
3. You can use a ROS sander with progressively finer grits to remove any machine marks.
Using hand tools:
You can use a hand plane to square, flatten and dimension your rough sawn material. Very little hand sanding will be required after using a hand plane. Why?
It's the manner in which the plane removes the material... a linear motion removing a thin shaving and leaving a smooth surface. Obviously, hand tools will take much longer to surface a pile of rough sawn wood than power tools. I use power tools for that.
Now what? Should you sand or scrape the surface using a hand held "card" scraper? Here's both sides of that discussion:
I have become a fan of scraping in conjunction with sanding. It leaves a smooth surface ready for finishing.
Sanding is "abrasive" in nature and remove the fibers of the wood by small sharp protrusions, the grit. You must work through the whole range of grits to eliminate the coarser lines made by the previous grit. Then repeat again with a finer grit until you have removed all the swirl marks.
Planing is a shearing operation rather than abrasive which slices the fibers off cleanly leaving a smooth surface. Power planing is a "scooping" action removing minute chips, unlike hand planing which removes thin shavings. So, hand planing leaves a smoother surface than power planing. This is why most completely equipped shops have both a power planer and a wide belt or drum sander.
Now you can apply the finish. Sealing the wood surface leaves a smooth, but not perfect surface. Sanding will level it out and remove any "pips" of dust that settled on it. Then you apply a series of top coats and sand lightly between them to build a perfectly smooth surface. OR you can use a scraper and lightly drag it across the surface removing any pips and leaving a glass smooth surface.
Then you can buff it out if you want a high gloss surface that reflects like a mirror. The buffing compound contains very finely ground abrasives that polish the surface. There are different grits of buffing compound as well.
The only time I have buffed a surface is on automotive applications. Some 2 part finishes come out so sooth and glossy, that no buffing is needed. :smile3: