Thanks for the comments guys!
And of course I'd be glad to give you a hand if you ever will make a crawler!
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some of you guys might have realized already, but I do like to use a pen as a tubing materiel since I can't really get my hand on any brass tubes or anything better...
It seems to be spinning freely in there, so all I need to do is to take out my JB-weld epoxy glue and glue the crap out of the axle to make it stronger!