My boxes

[GECKO]

Also avoid over sanding. Corners and edges look a like power sander was used instead of lightly hand sanding. I suspect that due to the amount of wood that was removed.

Have you checked the accuracy of your saw lately? Sometimes they need a fine tuning.

I only use a power sander to remove band saw marks when resawing boards.
I do check my fence alinement regularly.
Most of the time I use my cross cut sleds. One for ninety degrees and one for 45 degrees. I will check those today.

 

[Webb]

Check accuracy of the sleds too. Cut and flip one side. It should be perfectly straight for a ninety. A 45 should make a perfect 90 and use a square to check it.