[despaired student]

Hi,

today I tried to mirror some blocks but it didn't work out as I wanted it to ...
Some of the mirrored blocks edges do not fit as they should. (figure below)

How can I fix this problem. Later on I'll create O-grids around all inner cylinders and I would like to mirror them instead of creating O-grids at every 73 cylinder.

Another problem appeared when I "pre-meshed" the blocks - just for fun. (figure below)

Maybe there are some key-procedures I didn't do/ don't know. Or my strategy is bad. If someone knows a better strategy to block my geometry please tell me. I'd be happy to better understand this program. (geometry below)
It's a membrane reactor; a large cylinder with several small (membrane)cylinders inside plus in- and outlet.


Thanks in advance!

Sören