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FLAT HEAD MACHINE SCREWS
Head Dimensions
82°
Flat Head		 82° Undercut
Flat Head		 100°
Flat Head		 Torx® Drive
Flat Head		 Square Drive
Flat Head		 Pozidriv°
(Type 1A)
Flat Head



Head Dimensions for 82° Flat Head Machine Screws - ANSI B18.6.3 - 1998
Nominal
Size		 A H J T M R N F G Phillips
Driver
Size
Head Dimensions * Slot Dimensions Recess Dimensions Protusion Above
Gaging Diameter		 Gaging
Diameter
Diameter Height Width Depth Dia Depth Width
Max Min Max Min Max Min Max Min Ref Ref Ref Max Min
0 .112 .096 .035 .026 .023 .016 .015 .010 .062 .035 .014 .026 .016 .078 0
1 .137 .120 .043 .033 .026 .019 .019 .012 .070 .043 .015 .028 .016 .101 0
2 .162 .144 .051 .040 .031 .023 .023 .015 .096 .055 .017 .029 .017 .124 1
3 .187 .167 .059 .047 .035 .027 .027 .017 .100 .060 .018 .031 .018 .148 1
4 .212 .191 .067 .055 .039 .031 .030 .020 .122 .081 .018 .032 .019 .172 1
5 .237 .215 .075 .062 .043 .035 .034 .022 .148 .074 .027 .034 .020 .196 2
6 .262 .238 .083 .069 .048 .039 .038 .024 .168 .094 .029 .036 .021 .220 2
8 .312 .285 .100 .084 .054 .045 .045 .029 .182 .110 .030 .039 .023 .267 2
10 .362 .333 .116 .098 .060 .050 .053 .034 .198 .124 .032 .042 .025 .313 2
12 .412 .380 .132 .112 .067 .056 .060 .039 .262 .144 .035 .045 .027 .362 3
1/4 .477 .442 .153 .131 .075 .064 .070 .046 .276 .160 .036 .050 .029 .424 3
5/16 .597 .556 .191 .165 .084 .072 .088 .058 .358 .205 .061 .057 .0345 .539 4
3/8 .717 .670 .230 .200 .094 .081 .106 .070 .386 .234 .065 .065 .039 .653 4
1/2 .815 .765 .223 .186 .106 .091 .103 .065 .418 .265 .069 .081 .049 .739 4
* Edge of head may be rounded or flat.

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Head Dimensions for 100° Flat Head Machine Screws - ANSI B18.6.3
Nominal
Size		 A H J T M R N F G Phillips
Driver
Size
Head Dimensions * Slot Dimensions Recess Dimensions Protusion Above
Gaging Diameter		 Gaging
Diameter
Diameter Height Width Depth Dia Depth Width
Max Min Max Min Max Min Max Min Ref Ref Ref Max Min
0 .112 .095 .026 .019 .023 .016 .013 .008 .054 .027 .013 .020 .012 .074 0
2 .162 .142 .037 .029 .031 .023 .019 .012 .088 .048 .012 .022 .014 .121 1
4 .212 .188 .049 .039 .039 .031 .024 .017 .110 .070 .018 .025 .016 .167 1
6 .262 .235 .060 .049 .048 .039 .030 .022 .148 .074 .027 .028 .017 .214 2
8 .312 .282 .072 .060 .054 .045 .036 .027 .162 .090 .028 .031 .019 .261 2
10 .362 .329 .083 .070 .060 .050 .042 .031 .178 .104 .030 .034 .021 .307 2
1/4 .477 .437 .110 .094 .075 .064 .055 .042 .240 .124 .033 .040 .025 .415 3
* Edge of head may be rounded or flat.

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Head Dimensions for Undercut Flat Head Machine Screws - ANSI B18.6.3
Nom
Size		 L A H J T M R N F G Phillips
Driver
Size
These
Lengths
or Shorter
are
Undercut		 Head Dimensions * Slot Dimensions Recess Dimensions Protusion Above
Gaging Diameter		 Gaging
Diameter
Diameter Height Width Depth Dia Depth Width
Max Min Max Min Max Min Max Min Ref Ref Ref Max Min
0 1/8 .112 .096 .025 .018 .023 .016 .011 .007 .062 .035 .014 - - - 0
1 1/8 .137 .120 .031 .023 .026 .019 .014 .009 .070 .043 .015 - - - 0
2 1/8 .162 .144 .036 .028 .031 .023 .016 .011 .088 .048 .017 .029 .017 .124 1
4 3/16 .212 .191 .047 .038 .039 .031 .022 .014 .110 .070 .018 .032 .019 .172 1
5 3/16 .237 .215 .053 .043 .043 .035 .024 .016 .122 .081 .018 .034 .020 .196 1
6 3/16 .262 .238 .059 .048 .048 .039 .027 .017 .140 .066 .025 .036 .021 .220 2
8 1/4 .312 .285 .070 .058 .054 .045 .032 .021 .168 .094 .029 .039 .023 .267 2
10 5/16 .362 .333 .081 .068 .060 .050 .037 .024 .182 .110 .030 .042 .025 .313 2
12 3/8 .412 .380 .092 .078 .067 .056 .043 .028 .226 .110 .030 .045 .027 .362 3
1/4 7/16 .477 .442 .107 .092 .075 .064 .050 .032 .244 .124 .032 .050 .029 .424 3
5/16 1/2 .597 .556 .134 .116 .084 .072 .062 .041 .310 .157 .053 .057 .034 .539 4
3/8 9/16 .717 .670 .161 .140 .094 .081 .075 .049 .358 .205 .061 .065 .039 .653 4
1/2 3/4 .815 .765 .156 .130 .106 .091 .072 .046 .402 .252 .068 .081 .049 .739 4

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Head Dimensions for Torx® Drive Flat Head Machine Screws - Camcar
Nominal
Size		 G T B F Penetration
of "No-Go"
Gauge
(Fallaway)		 Torx®
Driver
Size
Head Diameter Head Height Recess
Diameter		 Gauge
Penetration
Max
Sharp		 Min
Sharp		 Abs Min Ref Ref Min
4 .225 .209 .195 .067 .094 .028 .019 T8
6 .279 .257 .244 .083 .111 .035 .022 T10
8 .332 .308 .292 .100 .132 .040 .026 T15
10 .385 .359 .340 .116 .155 .050 .031 T20
1/4 .507 .477 .452 .153 .200 .075 .040 T27
Torx° is a trademark of the Camcar Corporation, division of Textron Industries.

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Head Dimensions for Square Socket Flat Head Machine Screws - IFI
Nominal
Size
or Basic
Screw Diameter		 A H M T Driver
Size
Head Diameter Recess
Square		 Recess Depth Recess Penetration
Gaging Depth
Max Min Max Min Max Min Max Min
4 .1120 .212 .191 .071 .0696 .073 .063 .038 .032 0
6 .1380 .262 .238 .091 .090 .113 .105 .065 .057 1
8 .1640 .312 .285 .1126 .111 .140 .119 .075 .065 2
10 .1900 .362 .333 .1126 .111 .140 .119 .075 .065 2
12 .2130 .412 .380 .133 .1315 .165 .155 .095 .085 3
1/4 .2500 .477 .442 .133 .1315 .165 .155 .095 .085 3
5/16 .3125 .597 .556 .191 .1895 .201 .191 .100 .090 4
This type of recess has a square opening, slightly tapered sides and a conical bottom.

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Head Dimensions for Posidriv® Flat Head Machine Screws - ASME B18.6.3 - 1998
Nominal
Size		 A H M R N Recess
Penetration
Gaging
Depth		 F G Driver
Size
Head Dimensions Recess Dimensions Protrusion Above
Gaging Diameter		 Gaging
Diameter
Diameter Height Dia Depth Width
Max Min Max Min Ref Ref Ref Max Min Max Min
2 .162 .144 .051 .040 .096 .055 .029 .053 .037 .029 .017 .124 1
4 .212 .191 .067 .055 .122 .081 .030 .079 .063 .032 .019 .172 1
6 .262 .238 .083 .069 .168 .098 .041 .091 .073 .036 .021 .220 2
8 .312 .285 .100 .084 .182 .112 .041 .107 .089 .039 .023 .267 2
10 .362 .333 .116 .098 .198 .127 .041 .122 .104 .042 .025 .313 2
12 .412 .380 .132 .112 .262 .149 .056 .136 .118 .045 .027 .362 3
1/4 .477 .442 .153 .131 .276 .164 .057 .151 .133 .050 .029 .424 3
5/16 .597 .556 .191 .165 .358 .211 .086 .193 .175 .057 .034 .539 4
3/8 .717 .670 .230 .200 .368 .239 .086 .222 .204 .065 .039 .653 4
Posidriv® is a registered trademark of the Phillips Screw Company. Our fasteners with the "1A-drive"
are not manufactured by or connected with the producers of Pozidrive® fasteners.

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See also: Slotted Flat Head Cap Screws

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Smitty
Smith Fastener Company, A California Corporation - 3613 East Florence Avenue, Bell, California, 90201 - Phone: ( 323 ) 587-0382 - FAX: ( 323 ) 587-8712 - E-mail: sales@smithfast.com - Copyright © 2000 by Smith Fastener Company - Last updated: May 22nd, 2006 - http://www.smithfast.com/msflathead.htm