shape of concrete drill bits

[jfoldbar]

im a tradie who has spent his life with all kinds of tools. we often take for granted the thought that goes into designing most of these tools.

so i was drilling heaps of holes into stone last week. something ive done many times but not really thinking bout it.  i tried a different drill bit and was surprised how different it was. so then i got thinking about the science behind drill bit design and how i can learn more about it. after all, knowledge means being able to better choose the right tool for the job.

ive tried to find a youtube vid about this but cant. 

specifically id like to learn,for example, why/how the spirals are different shapes and angles, and the tungsten is different on different stone/concrete bits.

can anyone steer me towards a video or something. only really about the tungsten drill bits.

[StringJunky]

Not what you really want but you could look at the manufacturers sites and read their blurb behind their designs. If you look at the most expensive ones vs the budget ones you can see why the former might be better and the function of each aspect. For instance, good drills are double fluted with a high number of turns in the spiral for more efficient clearance and also sharper edges on the spiral so that the hole sides are cut cleaner, like a revolving chisel. The tungsten tip in good SDS bits often have a cross-shaped cutting edge so that the hole face is chipped finer and faster, which can lead to easier clearance. I like the Black and Decker Bullet tips for hammer drills, which have tips that are concave-pointed as opposed to straight-pointed, which is the norm. They seem to punch a hole better as opposed to just scraping a hole out and getting hot, like the conventional tips. I can do harder material with those bullet bits in a DIY battery hammer drill that I can't do with conventional bits... AND they can be used again and again! I don't know anything about tungsten quality, so that might matter as well.

Edited April 21, 2019 by StringJunky