How can i avoid making doubles when using subdivision modifier? Hello i learning blender and have a question about the subdivision modifier. I make the model as on the picture. I have a subdivision modifier on it. 
I know i can use loop cuts to make the rods not pointy, but the problem is when i use it they create doubles, i dont know if doubles is so big problem, but i heard its not really wanted. I allso know i can slide the loop cut just a little bit before the end edge and then it will not make any double, but it feels a bit not totally correct doing it that way, i dont know lol?.
My question is if this is the way of doing this? or are there better ways?
Doubles are generally a bad thing, as they are difficult to properly select, can cause artefacts, prevent cleaning whole model with Remove Doubles and can cause accidental unwanted merge when moving things with auto merge on. Sliding the loopcut just a bit before the end instead is totally fine way to do that, i really don't see what incorrect you see in that.