Fold Up Climb Training Board

I want to share a quick and easy build for your backyard that allows you to practise climbing moves and build strength when you're not at the climbing gym.

Like any experiment, I didn't want to pay too much for this, because I didn't know if I'd actually use it. I also wanted it to be out of the way, which meant it had to be flat pack, folding down into a single block that can be carried and stowed away somewhere - freestanding and portable.

To achieve this folding action, I came up with method to join lumber beams with steel tubing, which I had lying around in excess. This concept is hopefully applicable to lots of other wooden outdoor builds on this sort of scale.

For this particular setup, I built a set of rungs that would allow me to 'campus'. The aim with campusing is to train upper body strength by stepping or jumping between the rungs without using footholds.

I used the metric equivalent of 2" x 6" (pressure treated) lumber for the framework, and 38mm (1.5") steel tubing for the connectors.

The lumber I'd be using for the frame is sold in fixed lengths, so I wanted to make the most of each section by adjusting the size and incline of the triangular truss until I found the most economical combination of cuts. This was the advantage of using a highly parametric approach with CAD. With this I get a live calculations done for me as I tweak parameters: a readout of my cutting list, and the total number of whole lengths I need to buy.

The frame is made up of two folding triangular trusses, spaced apart and supported by a plywood panel and additional lumber supports that you can see in the later steps.

Each beam is cut to length and rounded over with a jigsaw, and then a hole is drilled out on either end to accomodate the metal connectors that will later allow the beams to pivot round one another.

I made a semi-circular template with the same width as each beam for the roundover, with a hole at the centre of the semi-circle so I can mark where I'll drill the hole too without measuring up each time.

I use a 40mm spade bit to quickly bore out large holes all the way through the softwood.

The action of the metal connectors mimics that of a slew bearing. It permits rotation of the beams past one another, but restricts lateral movements that would 'pry' the beams apart.

I began by cutting a length of steel tube that would stretch the thickness of two beams stacked together, plus about 30mm extra on each side, so it protrudes on both sides.

I held the short tube in a vice, and cut slots with the angle grinder along the length of the tube, just over 30mm deep. This leaves a slotted tube, with a solid middle section, and four 'leaves' on each end. Once inserted in the beams, I used a wrench to bend over these leaves as far as I could, and then finish the last part of the bend with a heavy hammer until they contact the face of the wood.

Two of the connectors (one of the joints in each triangle) are only slotted and bent on one side. This allows them to be pulled out carefully, essentially like locking pins, which mean I can hold the structure securely in position during use, and allow it to collapse down once they are removed.

Just a note on safety here: this is something I found to work robustly, but because they're not an off-the-shelf part, you'll have to do your own testing to make sure it's a safe, load-bearing setup. You definitely want to remove the sharp edges left over from the angle grinder too.

Now that I had two complete trusses, I folded them down into their bundles, laid them out and squared things up so I could affix a plywood panel to the innermost beams on the left and right, making up the surface to climb on. This links the two trusses along the longest side, and importantly cuts out the torsion that wants to force the framework out of square as you apply a load unevenly.

Before fixing on the panel, I added a few reinforcing 2" x 4" sections along the other face, which will raise the structure slightly off the grass and further prevent the frame from bowing inwards or outwards.

Sharp edges are best to avoid for climbing holds, because they're tough on your skin and your joints, and they splinter more easily. I therefore wanted to create rounded 'sloper' rungs, without a lathe or much other processing.

I opted for 95mm-thick square section fence posts, since these are made to survive outdoors, and about as cheap you can get for lumber of this size. Hardwood is definitely the gold standard for making holds for many reasons, but softwood will certainly suffice here.

I used a table saw with the blade set at 45 degrees to remove each corner from the square section, resulting in an octagonal prism.

From here I used a scrap of wood as a template to create a consistent hole at either end, which accomodates an M10 carriage bolt. The nice thing about low profile bolts is that there's no risk of scrapes, and they don't need countersinking. I was happy to secure the holds using washers and nuts from the other side, but you could also use standard M10 hex bolts and t-nuts which do make things slightly quicker when you're regularly resetting a board.

The great thing about a home setup is that you have free rein over what kind of holds and moves you want to set yourself.

With the dimensions of the board I went for, and being on the taller side, I won't be setting whole routes anytime soon, but it does give me the option to test particular moves in isolation. You can imagine that it could be set differently for a kids climbing frame though.

I had a go sculpting a freeform hold from a stacked plywood offcut, using a wood sculpting disk that fits onto an angle grinder, and this proved very successful. It only took about ten minutes because the shape of the block was already the kind of shape I was going for. I also tried a few bought holds, using t-nuts hammered into the back face to make it nice and quick to reset.