What spec says 90 degrees for metric flathead fasteners?
What spec says 90 degrees for metric flathead fasteners?
(OP)
Every time I order a metric flathead socket cap screw it has a 90 degree head. Every time I order an english flathead socket cap screw it has a 82 degree head.
Our data entry clerk asked me which degree I wanted when I asked her to put in a 1/4-20x7/8 FHSC into the system. I said if it is english, it's always 82 and metric, always 90. She said, "no it's not."
my questions are?
1) What governs this angle (ASME, etc)?
2) Is this true for only flathead "cap" screws?
3) What does "cap screw" mean?
Our data entry clerk asked me which degree I wanted when I asked her to put in a 1/4-20x7/8 FHSC into the system. I said if it is english, it's always 82 and metric, always 90. She said, "no it's not."
my questions are?
1) What governs this angle (ASME, etc)?
2) Is this true for only flathead "cap" screws?
3) What does "cap screw" mean?





RE: What spec says 90 degrees for metric flathead fasteners?
English flat head screws come in both 82 and 90 degrees. If I don't specify, I get 82 deg. I must specify if I want 90 deg. Don't know about metric. To answer your actual questions:
1) I believe it is governed by ASTM A574.
2) No, I have bought oval head screws that were 82 deg under the head, don't know if they make 90 deg oval heads.
3) No idea where the name cap screw came from.
Timelord
RE: What spec says 90 degrees for metric flathead fasteners?
The 100-degree head is ostensibly used in thin materials where the 82-deg. head would be too thick, though an undercut head would work as well. I have also heard that the 100 supposedly distributes the load a little more for soft materials, but I'm a little skeptical about how 9 degrees on a side is going to make a big difference, especially since the head and shank diameters are the same.
Don
Kansas City
RE: What spec says 90 degrees for metric flathead fasteners?
RE: What spec says 90 degrees for metric flathead fasteners?
Don
Kansas City
RE: What spec says 90 degrees for metric flathead fasteners?
TygerDawg
Blue Technik LLC
Advanced Robotics & Automation Engineering
www.bluetechnik.com
RE: What spec says 90 degrees for metric flathead fasteners?
From ht
UN screws are 82 or 100 as far as I know. Machineries may tell you the standard.
KENAT, probably the least qualified checker you'll ever meet...
RE: What spec says 90 degrees for metric flathead fasteners?
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