TYPE AA HEX LOCK BOLTS / PLACE BOLTS
The special head design of place bolts is designed to provide a “locking” action between the head of the bolt and the material being clamped. The combination of the recess under the head and the slots in the top of the head causes the head to flex as it is tightened. This creates a spring action in the head that provides additional elastic elongation that is not developed by standard hex head cap screws. This spring action provides increased resistance to loosening in high vibration applications. The width across the flat dimensions for 5/8" and 3/4" place bolts are one wrench size smaller than standard hex head cap screws. This smaller head size can provide added clearance for tight applications. The tolerance on the height of the head is also different for place bolts than standard hex cap screws. Earnest Machine Products’ line of Place Bolts are manufactured from alloy steel and are through hardened to a minimum tensile strength of 150,000 psi (Grade 8 per SAE J429) with a Rockwell Hardness of Rc 33/39.
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Size
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Width Across Flats
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Thickness
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|
A
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B (Max)
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|
1/4
|
7/16
|
.135
|
|
5/16
|
1/2
|
.198
|
|
3/8
|
9/16
|
.260
|
|
7/16
|
5/8
|
.291
|
|
1/2
|
3/4
|
.327
|
|
5/8
|
7/8
|
.390
|
|
3/4
|
1
|
.458
|