Placing mechanical anchors

Mechanical bolts are ideal when replacing a single bolt, replacing by hand drilling, or you need to immediately load the anchor. Sleeve and Wedge bolts are the most commonly used mechanical anchors. The ASCA distributes stainless powers 5 piece sleeve bolts of varying lengths for replacement work, and sleeve bolt placement is described here. We do not utilize wedge bolts for our replacement efforts.

tools required:

  • Hammer (stainless steel)

  • Torque wrench with compatible socket correctly sized for the bolt (9/16” for 1/2” powers)

  • Hammer drill and compatible masonry bits (sized to bolt manufacturer specifications)

  • Blow tube and tube/bottle brush for cleaning holes


preparation:

  • Be certain you are drilling the correct diameter and depth hole for the bolt you are placing, marking your drill bit with tape will help you measure if not using a depth guage on your drill.

  • If you are placing a wedge bolt drill the hole deeper than the total length of the bolt, this will allow easy patching in the future if the placement is discarded and the bolt is hammered in.

  • Worn drill bits can create a slightly smaller hole and make placement difficult. Discard bits when you notice that it takes more effort to hammer the bolt in place.

  • Always check rock quality even when reusing a hole after extracting an old bolt.

  • Consider camouflaging hangers, chains, etc. prior to placement to reduce visual impact, if not contrary to manufacturers instructions.

Placement:

  • Drill the hole at a perpendicular angle to the cliff face. Consider how the hanger will rest on the rock and how a quickdraw will hang and load when selecting bolt locations.

  • Keep your drill steady to prevent “wallowing out” the hole, especially in soft rock.

  • Clean the hole thoroughly using blow tube and brush.

  • Assemble the bolt and hanger before driving into the hole.

  • Make sure the cone is not expanding the sleeve when driving into the hole, this will make placement difficult or impossible.

  • Carefully tap the bolt into the hole until the cone is all the way in and the bolt is straight, then hammer all the way in, taking care not to hammer on the hanger.

  • Stop hammering immediately once the bolt is all the way in. Continued hammering at this point can break rock out around the cone and create a “spinner”.

  • Orient the hanger to the direction of pull and tighten the bolt. Torque specs for stainless bolts are significantly less than plated steel, and it is quite easy to over-tighten them, even with a short wrench- refer to the manufacturer’s specifications and use a torque wrench.

  • Make sure that the hanger is not spinning and sits flat on the cliff face.

  • Never seal mechanical anchors with caulking or adhesive.