Trying to Find a Pilot Drill Bit for a Concrete Core Drill Bit

last year

last modified: last year

I need to drill 1 5/8 inch drain holes into four inches of concrete at the bottom of a huge concrete pot. Because of the thickness, I was told to use "concrete core drill bits". I purchased a diamond concrete core drill bit as shown in the first photo:

https://www.amazon.com/dp/B0BWJCPD55

I then purchased an SDS Plus adapter that has 1 1/4 inch male threads to screw into that long concrete core drill bit:

https://www.amazon.com/dp/B0D2XN2Z15

The second photo shows what that SDS Plus adapter looks like from the top.

The problem is that once I assemble this I still do not have a pilot drill bit for the center of the concrete core.

The SDS Plus adapter shown in the second photo has a female screw thread in the middle that measures 3/4 inch wide. Where can I find a long concrete bit that screws into that middle section to give the concrete core bit a pilot drill bit? If there is no concrete drill bit that has a 3/4" male thread base, then how do I adapt to any system that is available for long concrete drill bits?

The third image below shows a different concrete core drill bit, that handles the pilot drill bit using a different type of adapter.

Featured Answer

millworkman

last year

last modified: last year

https://www.amazon.com/s?k=1+3%2F4+concrete+drill+bit&crid=32BWRTPL51O6&sprefix=%2Caps%2C85&ref=nb_sb_ss_recent_1_0recent

Try the above link.

Sort by:Oldest

Comments (6)

millworkman
last year
Why not just use a regular concrete bit and use the mandrel? Perfectly straight should not matter.
westes Zone 9b California SF Bay thanked millworkman
PRO
Joseph Corlett, LLC
last year
You don't need a pilot hole. Put the blue bit on a grinder, pull the trigger, and dig the tip into the pot at about the angle shown in your picture. Don't be bashful; both hands with authority. As it digs in, stand it up. This is how stone fabricators have drilled faucet holes millions of times.

Don't use a slow drill like this guy please. 2:30
westes Zone 9b California SF Bay thanked Joseph Corlett, LLC
Related Professionals
Greenville Landscape Architects & Landscape Designers · Santa Barbara Landscape Architects & Landscape Designers · Lawton Landscape Contractors · Dover Tile and Stone Contractors · Show Low Tile and Stone Contractors · Kalispell Tile and Stone Contractors · Mountain Home Home Remodeling · Olean Home Remodeling · Ashland General Contractors · Monroe General Contractors · Dover Bathroom Remodelers · Charlottesville Bathroom Remodelers · Fayetteville Furniture & Accessories · Lima Furniture & Accessories · West Palm Beach Kitchen & Bathroom Designers
westes Zone 9b California SF Bay
Original Author
last year
@Joseph Corlett, LLC I'm using a 1500 watt corded hammer drill in the drill-only mode. What rotation per minute speed would you use?

Seeing the video with the starting cut going in at an angle and slowly standing up will help, thanks. Would you make the first cut at a slower rotation speed?

My bit is very long, about 15 inches. It is tempting to use a slower rotation speed and try to use my hand near the cutting end to prevent the bit from bouncing. It's hard to control the bit tip when your drill is more than 15 inches from the cut.
westes Zone 9b California SF Bay
Original Author
last year
@millworkman Can you recommend a concrete drill bit that places a hole larger than 1.5 inches?
westes Zone 9b California SF Bay
Original Author
last year
last modified: last year
@millworkman I went for another core drill with a pilot bit built in:

https://www.amazon.com/Concrete-Connecting-Tungsten-Carbide-Cement/dp/B0DG5BSF1H

I can't believe I am able to buy that for $21. It's probably not a long-lasting tool, but I don't need to use it often.