How to keep axis of assembly velocity when a part rotates

Hello so i want to make a conveyor belt, of course so that parts can move down the conveyor belt into a teleport a bit like how tycoons do it. So basically I set the assemblyvelocity when the part is a certain rotation and it works however when i rotate the part the assemblyvelocity axis needs to change so that it still goes in the direction, ive been told to use ApplyImpulse but i couldnt get it to work. Is there a fix for this?