Thanks to a suggestion by Mobass, here are some of the bmx thread sizes and info.
One piece cranks take 1/2 inch pedals, 3 piece take 9/16th inch, in most cases.
1 inch is the standard size for older threaded forks, most bikes are 1 and 1/8 or threadless now. Not to be confused with the even newer internal head sets.
Most of the axles are 3/8 inch, with 26 tpi, (teeth per inch) I think skyways may be 24 tpi,
The seatposts vary quite abit in size, from 24 thru 27mm, depends on frame.