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I had to purchase a new 16" masonry drill bit for a project I am working on and it has the below grooves on the shank. I am curious why, but also want to know if there is a special drill that it is supposed to be used with, as I believe the grooves are causing the chuck in both a wired and battery drill I have not to center the bit in the chuck, which makes it very hard to put it in a position to not wobble all over the place!

Drill bit with grooves on shank

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Yes, that shank is for an SDS-plus chuck. It won't work well in a regular three-jaw chuck.

The SDS shank has the advantage of fitting into a simple spring-loaded chuck, so that bits are simply pushed into the chuck without tightening. This shank and chucks made for it are especially suited to hammer drilling with masonry drills in stone and concrete. The drill bit is not held solidly in the chuck, but can slide back and forth like a piston; it does not slip during rotation due to the non-circular shank cross-section, matching the chuck. The hammer of the drill acts to accelerate only the drill bit itself, and not the large mass of the chuck, which makes hammer drilling with an SDS shank drill bit much more productive than with other types of shank.

Rotational drive uses the sliding keyways that open to the end of the shank, which mate with keys in the chuck. The smaller indentations that do not open to the end are grasped by the chuck to prevent the drill bit falling out. The hammer of the drill hits the flat end of the shank. The shank must be lubricated with grease to allow it to slide in the chuck.

https://en.wikipedia.org/wiki/Drill_bit_shank#SDS_shank

  • Thanks, but wow SDS drills aren't cheap. Do you know if 16" drill bits (or ones around and in excess of this length) have to be SDS, instead of regular round ones? – user66001 Mar 4 at 1:06
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    Yes, you can get very long masonry bits with standard shanks, you may not be able to purchase them locally at big box stores but maybe local industrial supply stores and of course online. – batsplatsterson Mar 4 at 9:25
  • @user66001 I also thought that SDS aren't cheap. Since I got one, I now know how much time and effort I saved over, like, 3 years, and now I think my SDS was basically "free" in the long run ;) Depends where you live, of course. Here, concrete wall is way more common than drywall so mounting anything requires good drill. – Mołot Mar 4 at 10:47
  • Thanks Molot. Personally something being cheap or not only relates to it's purchase price. In terms of value for money though, I would agree with you. Alas I don't foresee myself needing to drill through concrete more than a couple of times in the upcoming years, so it isn't cheap and not good value for money to purchase a new drill, just for this one project (currently). – user66001 Mar 4 at 14:44
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If you are unable to return the bit or cannot find a standard bit in that length you can cut the SDS portion off. They still work as a standard masonry bit in a driver/hammer drill albeit not as well. I've done it in a pinch several times. By the way, SDS is well worth the money if you need to drill or chip masonry even occasionally. I've got at least one SDS MAX and two SDS plus drills in my truck at all times.

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