Bolt thread size

[wicklundrh]

I call them NKE bolts...

North Korean Engineering!

[canebreaker]

In another forum a member posted a link for metric threads. Looking for bolts/nuts we find a fine and course at most stores. There are 5 different thread pitches for an 8mm bolt on this chart. 8mm-1.25 is listed as an 8mm.
METRIC THREAD -- EXTENDED THREAD SIZE RANGE

[canebreaker]

Yesterday I got everything set up to drill/tap these aluminum rods my son gave me years ago. Suppose to be 7/16" dia, which would leave very little wall after tapping 8mm. I dug through my stash to find them. I look at the ends, thinking these aren't 7/16", they are 3/8". 8mm is 0.315, 3/8" is 0.375 which will leave 0.060 for the wall, 0.030 per side if centered correctly.
Now look to see what I can find, maybe 1/2".

[Fish on Line]

[Dave and Lynn]

You would need at least 1/2 rod to Drill and tap any 8mm hole.
8mmx1.25 is standard and should be drilled with 17/64th t0 7mm drill. If doing by hand I recommend the 17/64th. for an 8mmx1 thread you would use a j drill - 9/32nd. You might be able to take it to a local machine shop and they can help. They also would be able to tell you what pitch you have. and maybe drill and tap it for you for a small fee since it is only a couple of holes. Good luck.