How to Prevent Tablesaw Blade From Lowering Mid-cut

Sometimes, when cutting grooves or rabbets on my tablesaw, the depth of cut changes by as much as ¹⁄16". I use a shop-made throat plate that's level with the tabletop, and lock the blade height wheel. What's going on?
—Jerry Marshall, Ft. Mohave, Ariz.

If you're certain you've made the throat plate level with the saw table, Jerry, the most likely culprit might be backlash from the height adjustment. If you raise the blade and then lower it to the correct height, the arbor assembly can sink slightly as you cut. For consistent cutting depth, first lower the blade beneath your target cutting depth and then raise it to the final position, taking the backlash out of the blade-height-adjustment mechanism. Then lock it in position before making your cuts.