Coil Bolts: Dimensions & Specifications

Coil Thread Drawing

 

For fast assembly and disassembly of concrete forms, “coil thread” hex bolts are designed to be used with coiled thread hex nuts or coiled thread wing nuts. The "coil" thread is a large, self-cleaning thread with a rounded root thread shape (it is often advised to coat the threads with lubricant to make removal from concrete easier).

 

Coil Thread Length Drawing

 

Size

Width Across Flats
(A)
Width Across Corners
(B)
Head Thickness
(C)
Pitch
Max Min  Max  Min  Max Min  Nom
1/2"-6 .750 .725 .866 .826 .364 .302 .1667
3/4"-4 1/2 1.125 1.088 1.299 1.240 .524 .455 .2222

 

Thread Length - Coil bolts up to 6” in length are usually known as fully threaded, but the long space thread limits the thread length that can be used. The minimum available full thread lengths for the sizes borne by Earnest are listed below.

Size

Length Usable Thread
min
  Size Length Usable Thread
min
 
1/2-13 1 1/2 1.250   3/4-10 2 1.600
1/2-13 2 1.750   3/4-10 2 1/2 2.100
1/2-13 2 1/2 2.250   3/4-10 3 2.600
1/2-13 3 2.500   3/4-10 4 3.600
1/2-13 4 3.500   3/4-10 5 4.500
1/2-13 5 4.500   3/4-10 6 5.250
1/2-13 6 5.250        

 

Material -  Carbon Steel per ASTM A307 Grade A (60,000 psi tensile strength)

Size

  Safe Working Load
  Tension (lbs) Shear (lbs)
1/2"-6 Under 6"   4,125 2,750
6" & longer   6,750 4,500
3/4"-4 1/2   9,000 6,000
1"-3 1/2   18,000 12,000

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