how to drill a straight hole through a thick wall?

[dragonfly101]

I need to drill a couple of holes through 200mm internal wall for central heating pipes.

I'm guessing I want to drill from both sides and meet in the middle in order to avoid a messy exit hole.

Is there a good technique to ensure that the holes on both sides are aligned, and that I'm holding the drill straight?

 

[diyer56]

Not sure what diameter hole you require but you could drill a small hole straight through the wall and then expand with a larger drill bit from either side.

 

[Burnerman]

It may help if you can get someone to 'sight' the drill for you - especially in the vertical plane.
Start with a 10mm dia drill, and then increase the size.....if the wall is soft, it may just be possible to 'bend' the drill a little.
Sleeve those pipes, too!
John

 

[ntb]

If you have a pillar drill, get a thick piece of wood, drill a suitable hole in it as a guide, screw it to the wall and drill through. If going in one direction only, switch hammer action off for the last couple of inches to reduce exit damage.