[Closed] Drill guide recommendations?

What the hell are you putting on this shelf that needs 300mm drill bit.

Do you live in. Nuclear bunker

I just drilled a template on a bit of cardboard into the wood (I was using a big bit of oak for a mantle piece) transferred the template to wall and levelled up, drilled wall without worrying too much about how straight it was. Popped a bit of treaded bar in the holes with some resin. Got out a square and straightened the bars a bit to get them At 90 to the wall. Waited for the resin to harden. Offered up the timber and whacked it on with a lump hammer. I was planning on drilling up into the threaded bar with some screws to secure it but to be honest it isn’t going anywhere.

300mm? Sure you won't come out the other side of the wall... 😆

What the hell are you putting on this shelf that needs 300mm drill bit.

He's putting a shelf up in next doors living room - social distancing innit.

attempting to answer the question I can recommend the Bosch DP500, wish I'd got it a very long time ago.  However it now seems to be insanely expensive so there has to be a cheaper option but if you can find it at a good price it rocks.

I length of 2 or 3" x1" is perfect. Drill through the 2x1 the distance want the holes apart.
Mount/hold it on the wall, level it up, drill through the holes into the wall. Do the same on the shelf.
Total cost £2.

Is disappoint 😜 expecting a thread about some new urban choons...

300mm, that’s some wall thickness - watch out for your neighbour’s telly!

Well people normally refer to a 7mm drill bit being 7mm diameter, so I was thinking it would be more of a round window than for a shelf...

Ah yeah....I was a bit too vague.
I need to drill the holes in the shelf straight. The shelf is just a big chunk of wood. Actually the floating brackets go 250mm deep into the wood with a 12mm diameter. That's the challenge. The holes for the plugs in the wall are no problem, they don't need that level of accuracy.

All of the specific fixings I looked at seemed more complicated than they needed to be IMO. That’s why I did the threaded bar and resin fix on mine.
Borrow a pillar drill?

Thanks OP, I did wonder!

I would say pillar drill too.

I very frequently need to make drilling guides, but I do that by pillar drilling through a piece of scrap first, holding it to the work and using it as a guide.

Presuming you've not got access to a pillar drill, a way to achieve something close might be a bit like the following. (Bear in mind it's 5am and I can't sleep and am out of it and should not currently be allowed near sharp implements 😉 )

This relies on the edge face that you're drilling being square to the main face.

Take a length of planed timber or mdf/ply that's rectangular in section, and something like 50mm wide

Cut it in half as square as you can.

Lay the pieces on the narrow edge on a nice flat surface and pivot them round towards each other like a hinge.
Stop about 90 degrees though a little further wouldn't hurt.

Lay another bit of wood diagonally across the edges a bit away from the corner and screw/nail/glue gun into place so that it braces the angled bits.

Fix some more of something on the outside of the corner (duct tape might work even)

Then putting your drill bit into the inside of the corner, use the two flat faces as a running reference to keep the drill bit straight.

I would use a brad-point bit to do as much as you can as it'll hold a line better.

Who knows, it might work. 🤔

Fat-fingered phone sketch

I'd just use my pillar drill personally... 😉

Pillar drill guide in scrap sounds like a good option. Good excuse to actually buy one!
Or a drill block like this, which is basically the same thing, pre drilled in metal.
https://smile.amazon.co.uk/dp/B07BVSMZ6T/ref=cm_sw_r_cp_apa_fabc_1A5CX1XSVAGRYP8B2YRF?_encoding=UTF8&psc=1

Cut a v notch in the end of a bit of scrap. If you have a 300mm long bit use a nice big piece of scrap. Place the drill in the exact location then slide the scrap up to it and then, without lifting the drill, tilt it until it's in the vnotch. Drill as far down as you can. Remove scrap continue drilling.

Counterintuitive perhaps but long drill will make it easier. You can add some registering scrap on the face of the main scrap to help keep it in location.

This will give you the advantage of a good length of support over that wee thing up there. If you make it 150mm deep you get 150mm straight hole to keep your drill on the right track when you take away the guide.

Doesn't have to be a v either. If you have something that will cut an edge groove narrower than the drill bit the drill can rest on the corners of that.

Cut a v notch in the end of a bit of scrap.

You have to cut the notch bang on square to the surface of course otherwise you're just leaning against an angle.

Creating the vee notch with planed timber avoids having to cut square.

This is very true. A good opportunity to nail square cuts 😁

If we are picking apart each others plans... Yours will be a total arsehole to balance on the edge of a board*

* This I say in jest. You are more skilleth than I by a long chalk.

If we are picking apart each others plans… Yours will be a total arsehole to balance on the edge of a board*

Slightly true enough of course, but all you do is screw a batten underneath which you can set up so it's dead centre. Batten on each edge if you like. 😉👍
I'm guessing it's a fairly chunky shelf too.
😊

Pffft. Coming in here with your well thought out plans.

Just eye ball it OP