EDiamondTools Wet Drill Core Bits for Hard Concrete, Granite, Brick, and Block - 11cm Diameter 2.5cm - 0.6cm -7 Threaded 30/40 Diamond Grits

Q: Is the 1.75" outside diameter? What diameter core does it recover?

The size listed if for the actual size of the hole it will drill. These are not intended to actually produce an intact core sample although they do to an extent. The core size diameter is not listed. I used the 1-1/4 " size to drill through 7" of granite. The core was nice and smooth but broke off about every 2 to 3 inches which made for easier drilling. Maybe with a larger size the core would hold up better.

Q: Will this fit in a cordless drill?

I dont see why not, im sure the Hulk could hold it in place, the drill made for this weighs 75lbs plus.

Q: Do i need a core drilling machine for the 5" core drill to go through basement floor or will a hd 1/2" drill work well enough?

Ive done my coring using a 1/2 inch veritable speed right angle drill, plenty of very slow running water , fyi 6-1/4” deep was my deepest hole core. It was not inches in circumference. I also bought the recommended shank. I hope this helps feel free to as anything else Re drill bit.

Q: Looking for a 1 1/8” wet core bit for drilling hard reinforced concrete. 20” drilling depth

You need a carbide drill bit for a hammer drill, not a hole saw bit, for 1,1/8 are pricey & keep in mind if it’s reinforced as you stated you have to be careful, if you hit rebar with the diamond tip will break making the bit useless , imo