Wedge bolt

Wedge Bolt

Removal of the wedge type bolt historically was unfeasible and the standard practice for replacement was to tighten the bolt as much as possible (possibly breaking the bolt in the process), cutting it with a hack saw, driving it into the original hole with a punch, and then patching/camouflaging the hole with epoxy. Ipso facto, a new hole had to be drilled for the replacement. Thankfully Greg German and the Action Committee for Eldorado devised a way to remove wedge bolts by spinning them in their hole and damaging the bolt until it no longer mechanically functions.


Wedge bolts are easily identifiable by their external threaded stud and hex nut. These are likely one of the most commonly installed type of bolts in North America, if not the world, for a number of reasons. Wedge bolts are readily available in both imperial and metric sizes and thus removal can be complicated by this as the tools will need to be specific to the diameter of the anchor and the thread pattern machined onto the anchor. The size of the nut is typically one of the easiest ways to figure out the size of the anchor.

Nut size Anchor diameter Thread pattern
9/16″ 3/8″ 3/8″-16 tpi
3/4″ 1/2″ 1/2″-13 tpi
17mm 10mm 10mm x 1.5mm
19mm 12mm 12mm x 1.75mm

It should be noted that the Fixe Triplex sleeve bolt could be easily mistaken for a wedge bolt. If a flanged sleeve can be seen between the nut and the hanger or behind the hanger, then the bolt is a Fixe Triplex and not a wedge bolt.

Theory of operation

A wedge bolt has two main components, the main body of the anchor which features a tapered cone at the end and external threads at the front, and an expansion clip. The expansion clip on a wedge bolt will ultimately be slightly larger than the diameter of the nominal hole it will be installed in. This causes an interference fit that requires the bolt to be lightly tapped into place with a hammer. The interference fit causes the sleeve to stay in place in the hole and when the nut is tightened it causes the central part of the bolt to be pulled back out of the hole causing the tapered cone to engaged in the expansion clip. This causes the expansion clip to expand and “wedge” the tapered cone into the clip, providing the expansion effect.

Removal theory

The expansion clip of the bolt is able to spin around the main body of the anchor. Conversely, the main body of the bolt is able to spin inside of the surrounding expansion clip. By attaching a drill to threads of the main anchor body with a special adapter, we can turn the bolt into a rudimentary lathe. We refer to this technique as “spinning”.

Spinning the bolt at high speed combined with water and rock debris from the hole or abrasive git added with the water, we can break down the expansion clip / tapered cone interface. Sometimes this is caused by galling (momentary adhesion and tearing of the grains in the steel, possibly leading to friction welding) or by cutting a shoulder into the tapered cone that will catch the edges of the expansion clip and prevent it from expanding.

This process requires a bit of a feel for what is happening inside of the hole. Over time one learns the “feel” of when a bolt is becoming disabled. When attempting to remove the bolt with a removal tool, if the tension keeps increasing without yielding that’s a clear sign the bolt needs to be spun further.


  • puller tool (c-clamp, “Doodad”, Hurley Jr., or hydraulic punch driver with appropriate adapting stud)
  • spinner tool (with matching thread pattern)
  • spray bottle for water (optionally, add abrasive grit to the water to create an abrasive mixture)
  • hammer
  • appropriate size wrench for the nut (see above table) — longer handle the better

Spinner tool

There are a few ideas of how to build the spinner tool that will adapt your drill to the exposed threaded stud of the wedge bolt. Here are the ideas.

Reducing coupling nut

This idea requires the use of a standard SDS Plus chuck to 1/2-20 adapter. This is the same thread pattern as a standard 1/2″ drill chuck and you can easily buy the adapters themselves or adapters packaged with drill bits. Next you’ll need to create an adapter for the thread pattern you need to adapt to. If you’re dealing with 3/8″ or 10mm wedge bolts this is relatively simple and you can buy a standard 1/2″-13 -> 3/8″-16 reducing coupling nut. Using a 1/2″-20 tap you can re-cut threads in the 1/2″-13 side. This won’t be as strong as straight 1/2-20 threads but it’s easier than trying to drill and tap precise holes if your hand tool game is rusty. Drill a 1/4″ diameter hole 1/2″ from the 3/8″ side through both sides of the coupling nut and insert a 1/4″ quick-release pin which acts as a stop-pin. If you’re dealing with 10mm bolts you can easily do the same with the 3/8″ side and a 10mm x 1.5mm tap.


You can ground down the threads on one end of a 3/8″ threaded rod to fit in a drill chuck and then screw your coupling nut with quick-release pin as from above to the threaded rod. You can purchase a drill chuck with an SDS adapter for about $10 on Amazon. This is heavier, but easier to make with minimal tools a (hack saw and a file or bench grinder). It will also be crustier and prone to be more imbalanced and the chuck will inevitably loosen up.

Example plated steel bolts; top is new, bottom has been spun and extracted
Example plated steel bolts; top is new, bottom has been spun and extracted

Extraction process