Metric thread web calculator variances

[PeterT]

I thought I made a prior typo error, but now that I input the exact same (custom) metric thread into 3 different web calculators I've bookmarked, I see they are giving me slightly different answers.
Has anyone had this same issue? For example M30 x 1 6g (external) just comparing major diameter & pitch diameter to spot check. If the calculator provides a min/max I averaged the two just for spot check

Metric screw thread: M Profile calculator

theoreticalmachinist.com

https://www.trfastenings.com/knowledge-base/thread-geometries/metric-fine

Metric Thread Calculator

Calculate external and internal metric thread dimensions including major diameter, minor diameter, pitch diameter and thread tolerance according to ISO 724 and ISO 965 standards.

amesweb.info

 

[whydontu]

The metric thread Bible is ISO 724. Crossover is ASME B1.13M.

https://cdn.standards.iteh.ai/samples/85104/9815392ad8904c9aa23cf7727e7b1dde/ISO-724-2023.pdf

If you’re interested I’ll see if I can find a full version.

 

[lucsimoneau]

Ok, here goes: using the M Profile Screw Thread limits from the MH 29th edition, pages 1878 to 1900, and comparing with tabulated values for the standard M30x1.5-6g thread size, we get the following values for:

M30X1.0-6g

MAX MAJOR DIA.: 29.974
MIN MAJOR DIA.: 29.794
MAX PITCH DIA.: 29.324
MIN PITCH DIA.: 29.199

 

[PeterT]

Thanks.... I think! :/
I made a typo on the Ames PD, now corrected, so this how they compare. I would never expected any discrepancy, but obviously there are subtleties to the standards or sources?
Close enough for what I need but I'll have to pay attention to this. Might explain when I was doing my CAD generate threads from formulas, they were a bit off.

 

[lucsimoneau]

Just looked up on Theoretical Machinist and it comes up with same results as I've calculated from MH:

 

[PeterT]

Oh for crying out loud, another data entry fart on my part. Thanks. Well, getting closer
OK I'm going to do my taxes now LOL