Angle Specifications Views: 24

Countersink angles for different standard flat-head screws: Flat-head screws follow different national standards with different angles - you MUST use the matching countersink angle, otherwise the head will not seat flat and gaps appear. Part 1 - Common standards and angles: 1) GB/T (China) - 90 degrees, the most common; most domestic flat-head screws are 90 (GB/T 68 slotted countersunk, GB/T 70.3 hex socket countersunk etc.); 2) ANSI/ASME (USA) - 82 degrees; common in North America; UNC/UNF flat-head screws, e.g. ANSI B18.6.3; 3) DIN (Germany) - 90 degrees; common in Europe; DIN 7991 (hex socket countersunk), DIN 963 (slotted countersunk); 4) JIS (Japan) - 90 degrees; Japan and Southeast Asia; JIS B 1111 (cross-recessed countersunk); 5) BS (UK) - generally 90, some specials 100; 6) ISO - generally 90; ISO 10642 (hex socket countersunk) is 90. Part 2 - Special angles: 1) 100 degrees - some automotive (GM, Ford standards) and aerospace use 100-degree screws - use 100-degree countersinks; 2) 120 degrees - some automotive and heavy machinery use 120: shallow countersink, large contact area; 3) 60 degrees - light chamfers and deburring, not a standard screw angle; 4) 110 degrees - some aerospace standards. Part 3 - How to confirm the screw angle: 1) read the packaging or spec sheet - proper makers mark standard and angle; 2) angle gauge - universal bevel protractor or angle gauge; 3) projector - most accurate; 4) trial fit - cut with different countersink angles and see which seats flat; 5) check the standard number. Part 4 - Consequences of mismatched angles: 1) head and hole do not mate - small contact area, gaps; 2) head does not seat flat - sticks out or one side floats; 3) weak fastening - small contact area, stripping or breakage; 4) poor appearance - gaps, uneven; 5) head damage - forced tightening deforms or cracks the head. Part 5 - Export notes: 1) to the US - 82-degree countersinks for ANSI screws; 2) to Europe - 90 for DIN/ISO; 3) to Japan - 90 for JIS; 4) automotive export - confirm the customer's angle (some plants use 100 or 120); 5) aerospace export - confirm the standard (special); 6) never assume - do not assume all flat-head screws are 90; confirm standard and angle before export. Part 6 - Our angle range: 1) 60 - light chamfers, deburring; 2) 82 - ANSI flat-head screws; 3) 90 - GB, DIN, JIS, ISO - the most common; 4) 100 - some automotive/aerospace standards; 5) 110 - some aerospace; 6) 120 - deep chamfers, large countersinks, some automotive; 7) custom angles - 75, 100, 110 etc. Part 7 - Selection advice: 1) domestic - 90, most versatile; 2) export to the US - 82; 3) export to Europe - 90; 4) automotive - confirm the customer's requirement (90, 100 or 120); 5) unsure - buy samples to test or ask the customer; 6) stock - keep 90 and 82 to cover most needs. Summary: screw angles vary by standard - GB/DIN/JIS/ISO use 90, ANSI uses 82, some automotive/aerospace use 100 or 120. Always use the matching countersink angle. We carry countersinks, spot facers in every angle - ask us for the right angle and size.