Q: Why is a 1/4" double expansion anchor called a 1/4" double expansion anchor?
A: The 1/4” refers to the diameter of the bolt that goes into the double expansion anchor. 3/4” double expansion anchor tells
you that a 3/4;” diameter bolt is used with the anchor.
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Q: Why is the hole size for a double expansion anchor so large? A 1/2" anchor requires a 7/8" hole?
A: The inside diameter of the anchor is 1/2” allowing a 1/2” bolt to be screwed into the anchor. The outside
diameter of the anchor is 7/8”, the difference between the 1/2” and 7/8” is the anchor body. All female type anchors
are configured like this.
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Q: How come there are no holding values for these anchors in base materials other than concrete?
A: Concrete is such that a specific PSI can be determined and replicated in real
application. Brick, block, stone and other base materials can very from one unit
to the next, mortar is different both in strength as well as amount.
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Q: Why do I need to know the length of the anchor?
A: Because the length of the anchor will determine how deep to drill you hole in the base material.
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Q: What other names are these type of anchors called?
The double expansion anchor is sometimes referred to as: double expansion shield, keystone double, double thunderloc, double, DMSA, or machine screw
anchor.