When I built my first climbing wall I needed climbing holds but didn't have much monies to purchase the holds. So I came up with the idea of just drilling holes through rocks and using them as the holds. But right from the beginning I encountered problems with the real rocks so I came up with solutions.
First get a bunch of rocks. To me Basalt lava rock worked the best. The basalt rock is soft to drill but very solid and tough overall. I used a hammer drill to drill the holes. First start with a 1/8" masonry drill bit and set the rock on a thin piece of plywood. The thicker the wood the more the wood takes away from the hammering power of the drill. So thin piece of wood is best. If the 1/8" drill bit drilled a hole entirely through the rock without breaking the rock in half I was closer to success with the hold. The drill bit usually blows out the last 1/4" of the rock hold where the wood stops the drill bit from continuing to drill into the driveway cement. Then I use a 3/8 drill bit, and then finally a 1/2" drill bit to widen the hole. Then wash the holds and let them completely dry. Prepare a flat surface and put wax paper onto it. Apply mixed Bondo to the bottom of the hold and then set it on the wax paper surface. Wait for a few minutes continually checking if the Bondo is beginning to set up (get hard). At that point use a razor knife to easily trim off the Bondo around the edges of the holds, then set them back down on the wax paper to dry fully. If you don't trim off the Bondo edges then you will need a grinder because Bondo gets tough once it is dry. Then easily redrill the bolt hole through the dry Bondo with a wood drill bit, and the hold is ready to be used on the climbing wall. If the drilled rocks are used on the wall without the Bondo, there is not a flat surface to surface pressure which causes the hold to spin and will create gouges in the wood climbing wall. Also if the climbing hold bolt is overtightened and there is a air gap between the hold and wall surface, the bolt starts ripping outward from the wall to meet up with the back of the climbing hold, or the climbing hold itself breaks in half. |
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