I met a guy years ago that told me he had tried to make selfbows and failed every time. He said he broke about 50 bows and had give up on the whole operation.
I invited him to my house to show him how to make a bow. I gave him a nice osage bow blank, turned my back on him for a minute while I ran the bandsaw and heard him cussing.
He had made a trip to my belt sander, was in a hurry and had the blank ruined in less than a minute.
Turned out that he always tried to hurry up the process and had 50, make that 51 broken bows to show for it.
I finally taught him to slow down and he started making pretty good bows.
Bottom line, if you have made a bunch of bows the belt sander is OK, if not, stick to your rasp and scrapers.