The crown is also a core drill, and if we are to be completely correct and according to GOST, then the hole drill can be of several types. I tried and had no problems. As I read somewhere, such crowns are positioned for drilling thick sheet metal. Thinking about the fact that the country was attacked by a "crown crisis", I went to the state department store, and there I saw crowns that I had never seen before. A large hole in sheet metal can be drilled (drilled, not drilled) in three ways. I initially thought that maybe I was blinded, or they are sold in some other department. The crown is all-metal, and only the center drill is removable. Okay, let’s drop that. Generally. Thank you for your understanding. And I saw a big muzzle there, not crowns for metal. This crown has a diameter of 30 mm and a tooth thickness of 2.4 mm. Everything that will be written below may contain inaccuracies. Here, for example, are photos from work when this crown was used I have bimetallic crowns at home, I can show them to you Well, at least I don’t know anymore. Well, I have high-speed steel crowns with thick teeth. This is me now about crowns for hand tools. But no, it wasn’t blind. But from experience, I can say that crowns with thick teeth of this type cut into metal more aggressively and cut through it faster. And because there were no others. Why did you buy this one then? Further, in turn https://jiji.com.gh/12-tyres/maxxis, they still differ in the shape of the "bowl" and the presence of spiral grooves for chip removal. With these naive questions, I turned to the nearest store employee. If you don’t go too deep and don’t try to seem too smart, then the crowns are bimetallic, made of high speed steel and with carbide teeth. They look like this
When I bought myself such a crown, before that I had experience of drilling only with bimetallic ones. Let’s look at the crown that I bought about 12 years ago, and almost the same one ordered from Ali about a year ago. That’s about the crowns and will be discussed in this short review. Is it worth taking them to Ali?
Not for magnetic drills and machines. The wall of the device or a metal box (and this is usually 1.5 mm) such a crown passes in a few seconds. And I drilled a million of such holes, and now in the review I will drill the first million. I needed a couple of crowns of a certain diameter, and without a second thought I went to the nearest construction hypermarket. And this item is sold separately. The crown cuts perfectly to this day. In this connection, their total cost is quite decent. The author is a "krivoruk master" and an amateur. And instead of the stock clamping screw for the hexagon, a regular one for a PH screwdriver was screwed in. Without packaging and blisters, it is possible that the local "spill". Well, let’s drill, of course… Here she is Although she has done a lot of holes. But I must tell you not critical. This means that the thickness of the “thick metal” is limited by this size. Life has not spared the teeth of this crown and in some places they are chipped Moreover, the height of the cup with teeth in the reviewed crowns is usually 6-8 mm. They are usually sold without a shank with a central drill. 
The central drill, of course, has already changed more than once (there should be a short one there). 
And not only in this store. Something may be wrong. 
I don’t remember the price, I bought it in joy and forgot it, because I was about to fall into despair. They are bimetallic because the material from which they are made is a combination of high speed steel and cobalt. Back to news »
I don’t have any tungsten carbide bits, but I could order them just for fun. There weren’t any. I have only one crown from that time. It was like I said 12 years ago. They just weren’t for sale. I really don’t know what’s the problem with drilling such metal with bimetal bits.
