Hi all, I’m learning so much from looking at everyone’s fantastic builds. I’m building something with wheels for the first time (a frame for a portable outdoor archery target). I see that some of you (Mc Fish and Rustin Manning) mounted two wheels on a shared axle, while others (Mark M) mounted the wheels separately. When would you choose one approach over the other? And what exactly is the rotating piece — is the wheel spinning on a fixed axle, or are the wheels fixed and the axle rotates within some other structure (like the PVC tubing)? Anyone willing to give me a short tutorial on wheels & axles? :DThank you!Ellen