Chosen Solution
is there a screw size chart for that device?(3gs) and how do I get it?
there are tons of video on youtube when you put in the search bar “dissasembly / assembly” and your device name. usually are HD videos, so it can help you identify your screws. had similar issue with some screw from iphone 5, just take the smallest and go for the smallest holes, screw and turn around. if they don’t fall out, it’s probably the correct diameter. try to @%^!* the length depending on the place where you put it. closer to the case is smaller screw.
@davey3t , David check the links below from ifixit Replacement guides, a lot of the screws are identified in the assy. of the 3G. Good luck. I hope this helped you out, if so let me know by pressing the helpful button. iPhone 3G Rear Case Replacement iPhone 3G Logic Board Replacement more guides for 3G below. iPhone 3G Repair
