I have a Marshall combo guitar amp that was built in 1978. Some of the bolts that hold the amp chassis into the case have been rounded out by previous owners.I took them to my local Fastenall and they fit in both the M5 metric sizing guide and the 10-32 guide. So I bought both M5 and 10-32 bolts.Being of British manufacture, I assumed the M5 was the one to use. Nope, ever so slightly too large diameter to fit in the T nuts. So I tried the 10-32. The diameter was perfect, but the threads were a bit off. I could get it to thread into the T nut about 1/4", but it was obviously binding at that point.If I hold one of the old bolts up against the M5, the threads mesh perfectly. Comparing them end to end, you can see that the M5 is just a hair larger diameter.Holding the old bolt to the 10-32 shows the diameter is an exact match, but holding thread to thread shows the threads don't mesh perfectly.Is, or was there a standard bolt size that is 10-32 diameter, but metric threads? via /r/DIY https://ift.tt/2NMO431
