rotate objects to match up perfectly with the grid axises

hey guys i want to know how to line things up at certain points of an object with the grids. sure i know you can type in rotaze Z and type 90, but its not going to work right. im sure thats a math formula to do it for these simple objects but sometimes complex objects theres no way to do a math formula at all

right here is a simple object though so please tell me how i match the faces of this object to the grid axises instead of the crease

https://www.dropbox.com/s/iv6uowv120kanza/grenadesubstance.obj?dl=0 <-- that is file. below is a picture of that i want. like i want a way to select a face of an object, and then have that entire object get snapped into place with that face i selected being in the axises of straight perfectly


with math i used its 22.5 but yea would like to know for non simple circles

What’s wrong with the Snap tools?

idk i use them all the time. how do i snap an entire object to face a certain way?

if you mean snapping with increments on and rotating, that will not give you a perfect straightness. will be off. its 22.5 degrees to get perfect for this specific 8 vert circle. increment will not do that right

what i want to do is grab an object and like tell blender that i want the face of a certain part to be the one that aligns straight

ty man ill have to try that out