I have boulder stone foundation and would like to drill a hole through it for a gas line. How can I do this?
The rocks in the foundation tend to be about 12 to 20 inches and diameter and they are mortared together.
Drill hole through rock wall
drillstone
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Yes, the drill chuck will mar the finish of the shelf. There is a slight chance of damage to the chuck. Plus, choking down on the bit, like that, obscures your view of the hole (the drill and chuck block it) -- making precision harder to accomplish.
The correct way to do this is to use a drill stop.
Drill stops are less likely to slip than tape or zip-ties, and are much better for precise and/or repeated drilling.
If marring the finish is an issue, clamp a piece of 1/8th plywood over the site and adjust the drill stop accordingly.
PS: A piece of wood over the hole is usually a good idea anyway, when drilling finished surfaces. It helps reduce both splintering and the scratching that occurs when flakes of drilled wood or metal whip around the bore site.
Ecnerwal raises a good point - I would want to know for sure what it is before drilling through it. Metal plates are often put in around wires and pipes specifically to stop you from accidentally drilling into them - you could break electrical wires or plumbing, potentially causing a fire or a flood.
The plates work like this image shows:
The best thing to do here probably isnt applying more force - either drill somewhere else, or open up a small hole in the wall around it so you can see what you are breaking, then decide if its still a good idea.
As for what will drill through it - it depends on exactly what it is and how thick it is. Drilling through strong thick steel requires lubricating oil so you dont overheat and damage the drill bits. They will dull very fast without it.
Best Answer
Diamond hole saws work well for this with water. If this is anything like the stone foundations I have worked with there will never be a straight mortar line that could be used. On one of the first walls I drilled through I used a hammer drill and bit , The hammer drill caused the rock to break out on the back side and it was very tough to repair. This is the type of drill. once I get about an inch in I chip out the center and go deeper repeating the chipping process as I get close to the bottom of the saw. A really Good quality one may make it depending on the rock type. Don't go cheap or you will spend more time getting new ones and even though they are close to the same size sometimes you ending up having a slightly larger bit the second time (also found this out the hard way)