VEVOR Diamond Core Drill, 4"/101mm Diameter Core Drill Bit, 9.5"/241mm Concrete Core Drill Bit, 5/8"-11 Thread Core Bit, Dry/Wet Drill Core Bits w/a Blade, Diamond Wet Coring Bit for Concrete Brick

Honestly didn’t think it would work but this thing is a beast. Definitely wouldn’t purchase if I was using it everyday but for the 5 holes I had to make it went right through red brick no problem

Finally got the holes drilled. Why would they send out a core bit when the pilot bit does not extend past the diamond cutting surfaces. The purpose of the pilot bit is to drill the concrete and stabilize the larger core bit. After the core bit starts cutting you need to remove the pilot bit because it has done what it's supposed too. If the pilot bit only extends even with the diamond segments it is not going to work. In the photo I took a white box and held it against the diamond segments of the core bit. You will notice the pilot bit only extends only to the edge of the box. There are only two possible reasons for this, either the pilot bit is too short or the core bit is too long. I did get the hole drilled by making a guide out of wood to cradle the bit so it would start cutting without bouncing all over the place. Not very happy with this supplier. I hope they reach out to me with an explanation.

The best!!!

This bit worked really well once it gets started correctly and is kept wet with a constant stream of water, but that’s a given when drilling stone, block, brick, or other forms of masonry. I drilled though red brick and the concrete block just behind it in about 10 minutes. But the pilot bit is terrible. The way that the arbor at the top of the drill tube is machined causes the pilot bit to be very lopsided. I fixed this by two different methods. The first, I put some tough wire around the pilot bit at the edge of the tube (see the picture) and I centered the pilot bit by using three pieces of wire one attached to every other tooth on the tube, I tightened the wire with lineman pliers. That worked ok as the wire would break away once the drill tube started into the block but before the pilot bit would go off to one side. But then for another job I improved on my design and drilled a three inch hole with wood hole drill into a piece of one inch wood. I sanded down the edges a bit so it would fit the tube loosely. I then placed this cutout, with a little black tape wrapped around it to make it snug, into the very front of the tube (see the other picture). This worked extremely well, as the drill tube went into the block, the wood cutout traveled up the drill tube. But once I got about three quarters or an inch into the tube I removed the wood cutout and the pilot bit since neither were necessary any longer. The bit sailed through the brick and concrete block. Perhaps the manufacturer could make a design change and have an insert that would keep the pilot bit centered but also ride up the tube as you bore the hole. All in all, this a good product for the money. Just remember to have someone help you and keep spraying water right onto the front of the bit and into the hole you are drilling. No matter what, never drill masonry dry, your bits will last much longer if you keep them cool and wet.

I used the 4" dia version to cut a hole into my driveway to run drainage with an angle grinder. This core drill worked great, I used a piece of plywood with a 4"hole to guide my start cut. I can see how using this core drill horizontally would be much trickier, it's a heavy bit. I didn't break any teeth, and the bit held up well. I was in a low spot so it was easy to keep water on the bit. I was impressed with the results.A few observations. I bought the version without a pilot bit. This core drill is so long that the narrow dia. pilot bit would probably be a joke. If I had to use this bit dry I would take lots of breaks and put it in front of a fan in between.

Work pretty good for the price of it.

Although I only have an old hammer drill (Hammer off) I drilled it wet. I first hammer-drilled a small hole through the wall. I then ran an evaporative cooler water supply line through the basement window into the inside of the basement. I inserted the water line into the small hole on the inside of the basement and stuffed some foam-rubber insulation around it so that water would come out to the outside of the wall in the center of the coring bit. I then mounted a piece of particle board with a 4-in hole in it to guide the bit. It worked really well! I am 70 years old and I was drilling the hole in a very awkward position but I'm quite happy with the way it turned out. I know that the bit teeth were wearing down, as they are supposed to, because I occasionally saw a sparkle of diamond dust in the water that came out. That coring bit is tough and it has several holes left in it!

I tried this core drill bit (no pilot) in three different drills, just to drill into Aerated Autoclave Concrete block (AAC). AAC is sort of like concrete styrofoam, it's fairly light and cuts easily with even just a handsaw.Myself and two others on my crew could not get this drill bit to work. It was very frustrating, to say the least.We tried coming in at an angle, and using it straight. We tried multiple drills, hammer drills, high torque, low torque, high speed low speed, corded and cordless. No idea why this didn't work other than the drill bit. I've seen people in videos online use this sort of core bit on AAC block, so I can only assume at this point that the problem is with the product.If the seller can tell me why this isn't working ans how to fix it, I will, and I will update my review.