m6 bolts and nuts

Hi All,

I'm trying to replace a m6 bolt. My new m6 bolt just cannot fit into the old nut, I measured the pitches of the bolts with a caliper, and the pitches are exactly the same.

Originally, I thought all any m6 bolt can fit into a m6 nut. However (and obviously), I'm wrong. I came across an article mentioning that blots have different thread forms ( http://www.roton.com/identify_threads.aspx ). When I looked closely to the threads of my bolts, I found that the thread forms are really different.

I'm just wondering who (or which countries) uses which thread form. Any information is greatly appreciated.

Yours sincerely, Gary

The metric system of threads is standard - M6 has two pitches, normal and fine. I suspect you have an imperial bolt that's 1/4inch, not an M6

[ PS metric nuts and machine scrows (the pedant's description of what you call a bolt!) usually have their size stamped on ]

It turns out that my m6 bolts are bigger than they should be because of some manufacturing issues (confirmed by the manufacturer). Thanks.

That's unusual - I'd never have thought of that!

That’s unusual - I’d never have thought of that!

ya, i felt the same when I heard that from the manufacturer. Just in case you might be curious, the bolts I’m talking about is make of PEEK with some custom designs. That’s should justify the manufacturer’s mistakes a tiny bit because of human interventions.