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Drilled Angles   

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Best Use: Desert sandstone; bolting on lead
Rock Type: Desert sandstone
Pros: Can place on lead
Cons: Loosen as they age; weak in straight out pulls

Drilled angles are common bolts in the desert southwest. Generally a 1/2” (i.e. BD #1 or baby angle) is hammered into a 3/8” hole. The shear strength of these bolts is relatively high; however, the axial strength is low. Drilled angles are popular for bolting soft rock on lead due to their reliable shear strength and relative ease of placement, but they can become loose over time and fail under low outward force.

Placement: Drilled baby angles use a 3/8” diameter hole drilled about four inches deep. Some advocate drilling the first one inch of the hole with a ½” drill bit and drilling the remainder with a 3/8” bit. This may help ensure that the eye of the piton sits near the rock’s surface, reducing deformation of the surface of the hole which could undermine the strength of the placement.

Removal: Drilled angles can often be funked out. The hole can then be drilled with a larger diameter bit and a glue-in can be installed. Since drilled angles are generally only found in soft rock, they should rarely be replaced with mechanical bolts.

Rock Climbing Photo: Drilled angle
Drilled angle

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