Drilling through walls.

Last week I had three occasions where I had to drill holes through double skin brick or brick/block walls. Twice for cables & once for a 15mm pipe. It got me thinking - sorry chaps.

No problem drilling the holes, but getting the alignment right would be a big help.

I drill from the inside to the outside usually. Wouldn't it be great if you knew exactly where the exit hole would be? Getting it on a mortar course would mean no breakout to make good.

So, the question; How could you achieve this?

In these days of straight line lasers, metal detectors etc, would it be possible to design a gadget to pinpoint the exit hole? Measuring helps, but its difficult if not impossible sometimes.

I'd pay good money for a device that could accurately do that.

Reply to
The Medway Handyman
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How deep do those metal detectors go? a square 2" metal plate held against the wall outside/inside and the metal detector operated in the vicinity? of the plate might do it?

Reply to
George

Hmm. You can transfer a level using a transparent pipe filled with water (wherever it goes in between, the water levels at the ends will be equal). A bit fiddly to set up, but perhaps there's scope for using the underlying principle with some sort of magic box at one or both ends?

Pete

Reply to
Pete Verdon

Drill from the outside using a small but long bit, one designed for alarm cable. That will not cause much damage to the wall if you take it easy. Once the hole is where you want it, drill from the inside out with the larger bit. Then it doesn't look nasty with bits of plaster and brick popping out. I have not see a device such as the one described. Go and patent something.

Reply to
john

If you're drilling from outside in and have an idea of where the hole might be?, get someone with a piece of 12"x3/8" square wood to hold it against the inside wall firmly as this will stop the plaster shattering around the drilled hole.

Its a bit lie drilling a hole in wood...you put a piece of scrap wood underneath to stop the wood splintering on the other side.

Reply to
George

There ya go do you have the money? and a lighter.

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Reply to
George

They had a similar problem making sure the two ends of the Channel Tunnel would meet in the middle. Until the tunnel actually broke through, it was not even known how different the official "sea level" height was between Great Britain and Continental Europe. Once the tunnel was there, it could be measured of course, and separate teams from the UK and France both did so in parallel.

Reply to
Andrew Gabriel

That's a helluva long water level.

Reply to
Ian White

Fine for getting the correct vertical position, but useless for your horizontal measurement which will be just as important.

Reply to
A.Clews

There just is no way it can be done with the level of accuracy needed to get two separate holes to be a perfect meet in the middle - I too have thought long and hard over the years for a solution to the problem. Even if you can manage it good enough to mark two perfectly back to back marks on either side of the wall, there is still no certainty the holes will meet up in practise - unless you can keep the drill square and level. I just start with as thin a drill as possible to minimise the damage on the exit side and make a decision on which side to drill from based upon the practicalities each time. If there are useable points of reference on both sides of the wall, like door and window frames, you can get a useful idea of the exit point by measurement.

The best I can come up with assuming two people on the job is - As someone else suggested, a water level can be used to get an accurate height reference on both sides of the wall. Add to that a couple of laser pointers mounted on a rigid bracket, such that the bracket can be passed through a door or window opening with the lasers shining a line along either side of the wall. Where the laser lines cross the water level marks, is where you drill from each side. A bubble level might be useful fixed to the above laser bracket, to ensure it is level - plus some means to get it square against the wall.

Reply to
Harry Bloomfield

Good thinking Pete. Thats half the problem solved - getting the right horizontal - I have a proper water level (used for decking).

Now if I can just figure out the vertical....

Reply to
The Medway Handyman

But if you drill from the outside you can never be sure where its going to come out inside. Thats the problem.

Reply to
The Medway Handyman

unto the assembled multitudes:

But if all you want is to hit a mortar line to prevent having to make good, (from OP) then don't you just need to know the vertical position presuming of course that the bricks were laid horizontally. You do have to make sure the hole you drill is level :-)

Reply to
Peter Lynch

ISTR seeing such a device in a Screwfix catalogue a few years ago but there's no sign of it now. I think it involved attaching an ultrasonic source to the point where you wanted the hole to emerge and using a sensor to search for the strongest signal on the other side but I can't see any sign of it in the present catalogue or find it anywhere else with Google. No idea how accurate it was and I doubt if it'd have worked across a cavity wall.

Reply to
Mike Clarke

Yes, I remember seeing a newspaper cartoon at the time where they'd just broken throught, but the workers were scratching their heads as they'd managed to mate up the northernmost UK tunnel with the southernmost French tunnel (well, sorry, it was funnier in picture form).

Until the tunnel

And... what was the answer?!

David

Reply to
Lobster

can it really be that hard? a transmitter probe and a receiver/indicator like you say, in this day and age, it can;t be that hard.

Reply to
Vass

I've been thinking of a way to do this for a while. I need to drill a hole through a cellar wall to meet an external drain, and have yet to find a way to do it accurately. The answer may be magnets. The following is an extract from a US patent no longer available on the web:

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Currently, the problem of locating a potential drill bit exit hole on the blind side of the building structure may be done with careful measurements and visual estimation of where the through-hole will enter and exit the building structure. However, visual estimation is often inaccurate and taking measurements is sometimes tedious. Furthermore, both of these methods are time consuming.

Thus, there is a need for a method and apparatus for through-hole placement in a building structure that addresses the above described drawbacks.

SUMMARY

According to exemplary embodiments, the present invention provides a method and apparatus for through-hole placement used in conjunction with routing wires through partition walls including walls, floors, and ceilings of a building structure.

According to exemplary embodiments, the present invention provides a method and apparatus for positively locating both ends defining a potential through-hole before drilling the same.

According to one aspect, an apparatus for determining a location of a through-hole in a building structure includes a magnet disposed at a first location on a first side of the building structure. The first location is selected on the first side of the building structure that will define a first opening of the through-hole. A magnetic pointer is disposed at a second location on a second side opposite the first side in magnetic communication with the magnet. The magnetic pointer is configured to point to the magnet indicating a direction of the through-hole in the building structure defined by a second opening on the second side to the first opening on the first side when the through-hole is drilled.

Another aspect is a method for creating a through-hole in a building structure includes selecting a first location on a first side of the building structure that will define a first opening of the through-hole; disposing a magnet at the first location; selecting a second location on a second side opposite the first side via a magnetic pointer magnetically pointing to the magnet; and drilling the through-hole from the second side through the building structure in a direction indicated by the magnetic pointer creating the through-hole defined by the first and second openings on the first and second sides, respectively.

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No idea if this would work, but it seems there is a need for such a device.

Rob

Reply to
Rob

This wouldn't work with a standard magnet of decent enough size to carry around with you on jobs.

So whats needed is an electromagnet with a compass needle as the pinpointer source ie you secure the EM to the wall and go the other side of the wall and use the compass near to the EM till the Compasses needle is at its strongest pull.

Reply to
George

I use a 300mm x 6mm drill to make a pilot hole. With a bit of practice, it is not too difficult to use a large mirror to see you are holding it level. I then follow the pilot hole in from each side, towards the cavity.

Colin Bignell

Reply to
nightjar

When drilling for cables, I always drill from outside and angle the drill upwards. This prevents any water ingress. Using the final size drill, I then drill from the inside through the inner wall, reversing the angle and then do the same from the outside using the original angle. I have only ever managed not to meet up in a straight line once. I cured that by opening up the inner wall until I got a straight line and then made good with plaster.

Pipes should be easy. Drill from the outside, by either getting some one to sight you level in the vertical plane and use a small square in the horizontal, so that you can see that it is parallel from above. Open up to full size as above.

Dave

Reply to
Dave

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