Wrong Siemens bolt on panel screws?

Besoeker3

Senior Member
Location
UK
Occupation
Retired Electrical Engineer
10-32 is VERY close to M5-0.80. The 32 is 32 threads/inch for a pitch of 1/32" or 0.7938mm. A 10-32 screw will screw into a deeply tapped hole over 10mm.

Now for more than you wanted to know, the "English" number system derivation is not known to me, but the size "N" can be converted to inches by 13*N+0.060. Thus a #10 screw is 0.190". The M5 is 0.197".

Many think that a #10 is 3/16"; close, but not exact. What I've been told by 2 different fastener salesmen many years ago is that the product tolerances are such that a modern (we're talking 1970s here, so better yet today) threading machines can make a thread that will meet both the 3/16"(0.1875") and the #10 (0.190") dimension standards, so one screw is sold for both. I'm not sure ...
We used to use Imperial (not English) and the screw threads were Whitworth. Now we use Metric and have done so for decades.
 

GeorgeB

ElectroHydraulics engineer (retired)
Location
Greenville SC
Occupation
Retired
Unless you are talking some very very specialized precision threads, most bolts or screws if you measure across the threaded portion it's easily 15 to 20 thou under nominal.
My experience with fasteners was jig and fixture design. I didn't find SHCS (which aren't REALLY specialized precision?) to be anywhere near that sloppy. But a typical 1/2" or 3/4" Grade 2 bolt, yes.
Even the grip portion is quite a bit undersized (unless of course you're talking about a stripper or shoulder bolt).
Again, SHCS, not that much under. And of course I'm also not including the diametrically ground usually stripper or shoulder bolts. Even the as-forged head height on a SHCS is very close; I've consistently found the height to be close enough to spec that it's dimension is consistently different between say a 16mm and 5/8" SHCS, 0.630" and 0.625".

NOT arguing, just expanding;
 

Frank DuVal

Senior Member
Location
Fredericksburg, VA 21 Hours from Winged Horses wi
Occupation
Electrical Contractor, Electrical Engineer
Would be about 5 mm here. I am quite conversant with inches and metres. Gauge numbers like 10-32 i'd have to use a converter like Google.
And a 5 mm fastener is 5 mm here also. The #0 to #14 are not metric and there is no conversion. Same with 1/4" and up. Yes, some do seem to interchange, but to make tolerances not work against you, stick with the proper fastener. ;)
 

Frank DuVal

Senior Member
Location
Fredericksburg, VA 21 Hours from Winged Horses wi
Occupation
Electrical Contractor, Electrical Engineer
We used to use Imperial (not English) and the screw threads were Whitworth. Now we use Metric and have done so for decades.
Ah, but, there was a time when the US and England tried to use common fasteners, to win WWII. The result was a change to US fasteners and became ISO Inch standard. And people think ISO means only Metric. Well, if ISO Metric, then yes. Here is a brief explanation:

 
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