Can using a hex key to disassemble LEGO Technic pieces cause damage? Does using the right size hex key (Allen key) to speed up the disassembly process cause damage to the LEGO Technic pieces?
Yes
A hex key, being tough metal, is inherently a danger to ABS plastic. Using it to push axles and pop connections will eventually scratch and wear down your parts, something you don't want with technic pieces.