Have had some trouble assembling the case and batteries with the m8 threaded rods efficiency; the threads kept catching on the inside edges of the cells. I have managed to solve the issue by grinding the small end sleeves down. This has increased the hole size to 9mm diameter, perfect for 9od/8id brass rods that are now used as sleeves to ensure the inner surface of the hole is smooth. Should make life a lot easier and prevent potential damage to the poach cells during maintenance and assembly.