UKC

I'm building a wall and I wnant to be able to add bolt on holds, is it M6 T-nuts I need? What size hole should I drill as I see different suggestions.

Thank you

Depends on the size of the holes in the holds.

I think most are M10. Check with supplier or ebay vendor.

Was tempted to go all screw on but glad i didn't. 

Buy an Allen key bit set for an electric screwdriver! You don't want to tighten that lot up with a manual L shaped Allen key!

And borrow or buy a [battery] drill-driver! A decent one with enough oomph to power flat/spade drill bits

M10 is standard on all climbing holds, M6 would be tiny.

I think I drilled 13mm holes for the T nuts, the internal bore is 10mm (of course!) plus an allowance for the wall thickness of the T nut, say 1mm each side plus a bit of "slack" so it isn't too hard to push them in. 12mm might be ok but could be a bit tight.

I think I used 12mm and it was a tight hammer in fit. I think you'll struggle to find any holds that aren't m10. Buy the t-nuts first, measure then start drilling.

When you buy bolts, check if your holds need a tapered or flat seated bolt.

Using the wrong one will damage the hold hole after being tightened a few times.

A drill guide is useful, to make sure that you drill at a right angle.  I managed to get one in a charity shop. Otherwise your T-nuts will be harder to get in and stay flush (particularly the hammer in ones).

If you are drilling hundreds of holes, invest in a good quality wood bit. My battery drill wasn't powerful enough so I used a mains drill.

If you are following the same pattern, you may be able to drill two sheets at once.

Suggest you play with some scrap ply first, before committing to putting holes in your costly plywood sheets

Not sure if this link will work or not but this was my lockdown project if you want some inspiration

https://photos.app.goo.gl/WsdQNzhY7ZgFKCY39

One of these bad boys will go through a stack of 4 boards like its a sheet of paper.

https://www.amazon.co.uk/gp/product/B00BJ3QMLI/ref=ppx_yo_dt_b_search_asin_...

I'd 2nd the suggestion of a drill stand, they don't cost much and will save you drilling wonky holes in your pricey ply.

Thanks for all the suggestions, plenty of food for thought

That’s very impressive, not sure it’s the perfect design to keep me psyched through a Welsh winter!

That looks useful, cheers

I used wood bits but was careful not to drill right through, so i drilled from both sides, if you see what i mean. If you drill straight through you risk messing up the ply around the exit hole where the t nut needs to sits and and needs to grip.

There is a Facebook group with loads of info. 

12mm wood drill, M10 tnut. Wear ear defenders when you’re knocking them in, it helps avoid tinitus later in life. If you’re drilling multiple boards at once, get a pillar stand.

if you’re not going to add a securing screw behind each one, then get an m10 cap head bolt and check it screws easily into each tnut. A real pain, but worth it in the long run if the back isn’t accessible.

tbh. my home wall only has t nuts because I used legacy boards from previous houses. The back wall is pretty well all screw ons. If I leave this wall in situ when we sell the house.  I wouldn’t bother with t nuts in a new build. Wooden screw ons are more skin friendly, and make for a more flexible setup imho.

Having drilled thousands of holes for a couple of commercial wall rebuilds, I can highly recommend using a router rather than a drill. Much easier to keep the holes perpendicular, plus if you set the depth correctly you can drill through multiple sheets at the same time and also mark the lowest board with the tip of the bit ready to drill afterwards. 

Don't happen to be in South Wales do you? I have a stack of t-nuts from my build left over

I don’t think I can justify buying another power tool just for this! I’ve been recommended screwing them on directly with counter sunk washers so I am going to try that. 

Thanks for the offer but I am in North Wales which means, given the transport links, I’m effectively further away from you than if I was living in any part of England!

Thanks for the tips, I’ve been advised that screws are good for bolt on holds as well, with the correct washers, so I’m probably going to go that way. Maybe a few t-nuts for the biggest jugs I use to red in etc. 
Nice board BTW!

When I did the kid's climbing frame, it was a 10mm drill and M8 T-nuts with a 6-mm hex key.

Think that's a standard size.

It's a fair weather wall. But living in the south east the fair weather lasts a tad longer.

We’ve had our first flood warning of the winter! I’m impressed by the paint job, you should have done some hip hop graffiti to startle the neighbours!

It was floor paint. Cost a small fortune but hard wearing and waterproof and has held up really well. Ye the goal was subtle camouflage. Although it ended up more subtle than intended.

I highly, highly recommend screw ins unless you have easy access to the back of the board (and even then I'd get screw ins personally). You drill them at 13mm and they just sit in the hole with some clearance (no hammering). Use torx screws and they go in really fast - (3.5 x 16mm T15 Torx Self Countersinking Screws)

Its worth getting the tnuts you can put a small screw in the back of rather than the bang in ones if the back of your board isn't easily accessible.

If you go for the 4 prongs (hammer jobbies) then a 6" chopped off end of a broom handle or similar worked well to hammer onto them with a mallet. 

M10 tee nuts and 13mm holes. 

Top tips:

- Work out where the sub-structure (wood batons) go before you layout/drill the holes - you should keep a clear >25mm from any baton (more if you might be imprecise in your construction). A tee-nut in the wrong place is a pain in the arse.

- I'd strongly advise you fix the tee nuts on the back - either buy tee nuts with screw holes or if you have pronged ones simply screw a short screw in against the notch where prongs go. I't usually a PITA to replace them one they pop out.

- Back the ply when you drill the holes to protect from making a big mess on the back side and drill from the front side to the back to have the neatest holes on the front. Stack all the boards with the same baton pattern and drill them all at once.

- Having made walls with neat grids and random holes I can say that unless you are building something like a moon board random holes are better and easier.  Just throw the required number of tee nuts on the board - even them out, avoid the baton areas and drill them where they lay.

- It's definitely work investing in a nice 13mm drill bit - typical hole densities are ~70 holes per board which is a lot of drilling.

- Holes are over-rated and a lot of home made walls use home made holds which are screwed direct to the boards, you may not want them as much as you think you do!

- Hammering in 100s of tee-nuts is very loud and tedious and hard on the knees, prepare accordingly!