Core drilling through a THICK wall

[contactjr]

Hi,

I need to drill a hole through an external wall for a new shower waste pipe. The problem is that my house was built in 1901 and the walls are just under 2 foot thick! The construction is of stone (solid I think) although not particularly hard stone - I have found it easy to drill holes in, even with cheap masonry bits. I think it is a type of sandstone.

Looking at core drills, I think I need a 50mm diameter drill for the 40mm pipe to allow for a bit of jiggling around, but they all seem to be of a maximum length of 150mm. I have read elsewhere about drilling to the max depth and then breaking off the core before starting again, using arbor extensions as you get deeper in. How easy is it to break off the core and with what and how do you do it, especially when drilling through a wall of such thickness.

Any tips or experiences would be much appreciated.

Thanks

 

[Gasguru]

Is the wall random stone rubble construction? If so you may find the stones just wobble around and you break off the diamond segments. The middle infill is often just full of crushed stone and any other rubbish lying to hand. Be prepared to pull the wall apart by hand.

 

[bengasman]

Drill a pilot hole through, so you can drill from 2 sides if need be

 

[ChrisR]

I don't think you'll have a problem. The rubble stops falling, eventually. On of those wonderful 6ft crowbars rammed into the hole would smash any obstacles you couldn't drill.
The core bits work much better without a pilot , and they wander a bit, so I think the chances of meeting up if driling from both sides are not good.

You'll need a vac to clear the dust spoil from the bit or it'll clog up.

 

[coxius]

I had a similar problem - putting a soil pipe through a wall 3ft thick. Wall was soft sandstone.

I'd suggest popping to your local hire shop, getting a decent corer with a clutch, with a diamond drill bit. Get a few extension bars (I used two), and (the most important bit) make sure everything looks new and is straight. If the extension bars are at all bent (even slightly) the corer will jam in the hole.
Also big solid extension bars are obviuosly better. My first attempt I was given thin extension bars which were slightly deformed. That, plus the fact I was using a power drill, meant that the bit jammed.

You should be able to core all the way through no problem. Avoid going from both sides as there is sod all chance of meeting in the middle.

 

[bengasman]

You should be able to core all the way through no problem. Avoid going from both sides as there is s** all chance of meeting in the middle.

how would a drill deviate if the drill guide follows the pilot hole? wherever possible i drill a pilot hole from the inside to mark the position of the flue and do the messy drilling of 117 mm core from the outside. never fails, solid wall or cavity wall