Very interesting, so could you measure the sizes of your bolts and nuts? (sounds weird lol =) I mean measure hardware you use, not Your Hardware)) ), your thread diameter, and the size of the hex on the nut (size of wrench)
I’ve got two options which are both not good.
1. If I go using M3.5 bolts – that will give me: Thread Diameter = 3.5mm, wrench size = 5.5mm (this is specification for metric M3.5 bolts). So, I will fit in the hole which is 3.5-4mm, but the nut will not be trapped by the 8mm wrench trap. (and the bad thing is also that there is no space to hold the nut by wrench)
2. If I go using M5 bolts – that will give me: Thread Diameter = 5mm, wrench size = 8mm (this is specification for metric M5 bolts). So, I will not fit in the hole without drilling it from 4 to 5mm, but the wrench size of the M5 nut is exactly as printed nut traps.