How To Measure An Allen Head Socket Cap Bolt (VIDEO)


Tips For Understanding the Allen Head Socket Cap Bolt:

  • When measuring an Allen Head Socket Cap bolt, do not include the head. Measure from the tip of the bolt to underneath the head. ***Flat Head Bolts (aka Matini Bolts) are NOT measured the same way. Flat Head Bolt lengths include the head in the measurement.***
  • Any climbing hold bolt longer than 1-1/2" has a smooth shoulder underneath the head. The smooth shoulder is called the shank. Below you will find the lengths of the shanks and available thread for each length of bolt we carry.
  • The North American Climbing Industry uses is a 3/8-16 Allen Head Socket Cap Bolt. 3/8" is the diameter of the bolt. 16 is the thread count per inch. We use this type of bolt because the wrench fits inside the head. This allows us to design holds with a smaller Shoulder Tower. This is desirable to stop a climber from sticking their fingers in there.
  • On our website, WALL TYPE refers to the thickness of your climbing wall panel. Most walls are 3/4" plywood. We see the 5/4" Board and 1-1/2" thick (2" x 6") Board on outdoor walls. Wall type tells our software which length of the bolt to choose for that specific set.
  • When tooling a climbing hold during the initial shaping process, we tool the grip so that the bolt head is just below the face of the hold. The Shoulder Tower keeps the bolt recessed so that when you grab the hold, you won't feel a bolt head digging into your hand. Because of this, sets often have different lengths of bolts.

Allen Head Socket Cap Bolt Lengths with Shank and Thread Length Measurements

Bolt Length ShankThread Length
1-1/2" 0" 1-1/2"
2" 1/2" 1-1/2"
2-1/2" 1" 1-1/2"
3" 1-5/8" 1-3/8"
3-1/2" 2-1/8"  1-3/8" 
4" 2-3/8" 1-5/8"
4-1/2" 2-7/8" 1-5/8"
5" 3-3/8"  1-5/8" 
5-1/2" 3-7/8" 1-5/8"
Bolt Length ShankThread Length
6" 4-3/8" 1-5/8" 
6-1/2" 4-7/8"1-5/8"
7" 5-3/8" 1-5/8" 
7-1/2" 5-7/8" 1-5/8" 
8" 6-3/8" 1-5/8" 
9" 7-3/4"1-1/4"
10" 8-3/4"1-1/4"
11" 9-3/4"1-1/4"
12" 10-3/4"1-1/4"