Dry Core Bit for Brick and Concrete Block with Pilot Bit - 4" Diameter - 1/2" Shank Arbor - #30/40 Diamond

all good

It worked. I was able to drill through triple brick. It took awhile, and I would suggest stopping from time to time and allow the bit to cool down. There is a sticker affixed to it that specifically says not to use the hammer drill function, so heed its warning. Only downside is it’s a bit heavy, which I’m sure all coring bits are. It’s a workout on your arms for sure.

I ordered the 4.25 core bit with pilot so I could install a 4" dryer vent in my new house. I'm so glad I went with 4.25" but instead of 4" (I actually got the idea from these reviews on Amazon). The little bit of space around the duct was so helpful. I had to drill through 8" of hard concrete. I asked for quotes from several plumbers and a few local "handymen", nobody even wanted to quote this! They said it would be a huge project and really difficult. Well, this core bit did the job in less than ten mins! Literally 9 mins. I was amazed. A few things I will note, DEFINITELY use a powerful drill. I rented a 1" roto hammer drill from home depot for $40, wellll worth it. It went through 8 inches of concrete like it was butter. Another thing, if you use a hammer drill, you prob need to order an adapter. I made the mistake of not ordering this until AFTER I received the core bit, and I was forced to wait a few more days until the adapter was delivered (wasn't available in any local stores). Also, the adapter couldn't fit the pilot bit, so I took the advice of some of these reviews and I made a "holder" out of a wood plank (see photo). During the initial drilling, the bit would've jumped all over the place and damaged the wall if I didn't use this idea. I can't really speak for the longevity of this core bit, but I drilled through 8 inches of hard concrete and the bit still looks perfect.

Went through 12 inches of hard poured cement with large rocks in it. Took a few hours to avoid burning up the drill (A Bosch Bulldog). Takes a fairly powerful drill as mine was about limit for a 4 inches hole. I used water while drilling. And took out the core bit from the hole every couple of minute to dunk in it in a 5 gallon water bucket. I have no idea how many holes I'll be able to drill with it but it still seems in good shape.

Worked great on brick wall. Nice clean cut, no chipping of the brick. Even used on my battery drill NOT in hammer mode, in low. Took about 5 minutes to get all the way through, shorter than I expected! The bit is advertised as a dry bit but I used a spray bottle to keep it wet. Knocked off one star because there is an arbor in the photo and my bit didn't come with an arbor. Luckily had one, but wasn't able to use pilot bit because the arbor I have doesn't have the hole for pilot bit. Not a problem starting it slow at a slight angle.

Set this all up, seemed to be great. All went bad within 30 seconds of use. First, the primary bit would not stay tight in its arbor no matter what I tried Second, because the primary bit was loose, the block cutting would bind up causing either the drill to stop or worse kick and snap causing wrist and hand injury. Does not at all live up to standards. I ended up using regular masonry bits and the out line from this tool to drill multiple holes and complete the task. Sending this very dangerous item back as it did not at all perform properly. Be careful