Drilling brick from the backside

[LG63]

I’m rerouting some coax and need to drill several 3/8 holes thru brick. I’d like to drill from the inside of the house because that will allow me to get the most accurate placement. I drilled the first hole using my cordless hammer drill and a long masonry bit. I know that brick tends to break out when the bit exits so I took it easy as I came to end of the hole but it still knocked out a good sized divot when the bit broke through. I have several more holes to drill, any suggestions for minimizing the break out?

 

[gordyy]

if you know the length shut the hammer off an inch from the end
will take longer to drill but less breakout
or fasten a board against the brick as a backer

 

[Steevo]

Best way I have found is to use a small diameter bit (1/8"?) from the inside, and come back from the outside with the finished size.

 

[LG63]

Thanks, I'll try both those suggestions. I didn't think they made 12" masonry bits smaller than 3/8 but I found a 1/4 with a quick google search.

 

[zxttfan]

It's much better to go through the mortar joint if you can make it work with your setup.

 

[rslaback]

Use a masonry bit that will reach all the way through. Mark the drill bit to be about 1.25 to 1.5 inches from coming out the other side. Drill hole. Take a rare earth magnet or two and put it on the end of a 3/8" rod. Put the rod back in the hole. Take a compass to the other side. Move the compass around on the wall. The needle will either point directly toward or away (you can check before you stick it in the hole). Mark that spot. Drill back into building. Holes should roughly align. Use full bit length from outside if needed to gouge transition point to proper diameter.

 

[Nowater]

Wow ^^ what he said.

 

[LG63]

Use a masonry bit that will reach all the way through. Mark the drill bit to be about 1.25 to 1.5 inches from coming out the other side. Drill hole. Take a rare earth magnet or two and put it on the end of a 3/8" rod. Put the rod back in the hole. Take a compass to the other side. Move the compass around on the wall. The needle will either point directly toward or away (you can check before you stick it in the hole). Mark that spot. Drill back into building. Holes should roughly align. Use full bit length from outside if needed to gouge transition point to proper diameter.

This has to be one of the slickest tricks I've seen here on GJ. Now if I can make this work with the compass app on my smart phone, I'm all set.

 

[Engineer61]

Sorry, phone's use GPS to figure out north, not a magnetic field. You just need one of those real cheap compass's that get given away as door prizes etc to do this trick. Could also use a small nail, magnetize it first with the rare earth magnetic and tie a piece of thread in the middle of the nail, make sure it's level when you hold the thread and let it dangle, then use it like the compass needle.

 

[Tim The Tool Man]

Best way I have found is to use a small diameter bit (1/8"?) from the inside, and come back from the outside with the finished size.

^This is what I do. Easy peazy. For the one hole that spalled when you drilled it out, just pack a little extra duct seal around it and you'll never notice it.