How do you learn to hand-jam out a 20' roof?
Making a crack machine, or indoor wooden crack simulator for garage climbing, was actually pretty easy.
- 2 "2x12" boards, as long as you can fit in your climbing space
- About 8' of "all thread" (the threaded rod that determines width) - cut into 12" sections
- 4 washers and 4 nuts for each section of all thread
I drilled holes in the boards slighter wider than the all-thread. I then originally installed two pieces of all-thread at 6 different spots (12 total) along the length of the crack. This was overkill. I think all you need is one piece roughly every 2 feet, and you can put it through the boards in the middle of the board, or an inch toward the "jamming" edge. Use a drill to put matching holes through the boards and make sure to install them in the same orientation you had them in for drilling. Put a washer on the inside edge of all the nuts. I used 3/8" all-thread and washers. Having a 3/8" ratcheting quick wrench also really helps speed up any width adjustments. Consider drilling some big plastic hand/foot holds onto the sides for heel hooking or to use with one hand.
I drilled 4 small 2x4s to the rafters, then drilled the roof crack to the 2x4s. No sanding, no painting, no tape, and no scrapes or gobies to speak of. I have read of other folks using sandy paint mixtures and other artificial textures, but I think those would be pretty rough on the hands.