Volumes, chalk and bolts

Once the panel, the grid and a first set of holds exist, three small things decide whether the wall is pleasant to use: volumes, chalk, and bolts that actually clamp.

Volumes

A volume is a large hold, often a box or a curved block, bolted on with several screws. It moves your hips off the plywood. On a steep board that can turn a move from "pull harder" into "stand on the shape". On a vertical board it can be the only interesting feature in a small room.

The practical limits are boring.

• Each volume needs a flat patch of skin and T-nuts that match its hole pattern, or screws into timber you meant to screw into. A volume that bridges a sheet joint needs timber behind the joint.
• The bolts are longer levers than a small edge. The frame still has to be the structure from the fixings guide.
• Big shapes eat landing space in the sense that you fall from further out. Look at the mat area again after you add them, not before.

Start with one or two. A wall of volumes and no normal holds is a different, worse warm-up.

Chalk

Climbing chalk is magnesium carbonate. It takes sweat off skin so you stay on a hold. It also becomes dust on the mat, the car and the spare-room carpet. Loose chalk in a bucket is the usual home-wall choice because a chalk bag is a faff between problems. Liquid chalk dries on the hands and puts less dust in the air, and it is a poor refill for a bucket.

Ventilation matters more in a spare room than in a draughty garage. A closed bedroom with a chalk bucket is a decision the other people in the house will notice. There is no ranking of chalk brands here. Buy a plain magnesium carbonate meant for climbing, and keep it off the mat's seams, where dust hides and holds become glass.

Bolts

The bolt is right when three things are true at once.

1. The thread matches the T-nut. For a UK adult wall and for Moon's metric kits, that is M10. The grid page is where the nuts are specified.
2. The length matches the hold. The bolt passes through the hold and into the nut, and the hold clamps down before the bolt runs out of thread or hits the back of a closed nut. Too short, and a few threads are all that keep the hold. Too long, and the bolt tightens against the nut's end while the hold is still loose.
3. The head and any washer match the pocket in the hold, so the head is not a spike under your fingers.

The hold maker's bolt kit is the way to get all three without a micrometer. A mixed tub of "M10 bolts" from a drawer will include lengths that nearly work. Nearly is the hold that spins in month three.

ALPIDEX's note on their M10 nuts, paraphrased on the materials page, caps tightening at 30 Nm and tells you to keep glue out of the threads. That limit is about the nut in the plywood, not a licence to overtighten a plastic hold until it creaks. Snug, so the hold cannot spin, is the aim. A creaking hold is a reason to stop and look, not to fetch a longer bar on the Allen key.

Replace a bolt that comes out bent or with a damaged thread. The replacement is the same length and the same thread, not "the next one in the box".