The central drill, of course, has already changed more than once (there should be https://jiji.co.tz/power-equipments/transformer a short one there). A large hole in sheet metal can be drilled (drilled, not drilled) in three ways. I needed a couple of crowns of a certain diameter, and without a second thought I went to the nearest construction hypermarket. But no, it wasn’t blind. But I must tell you not critical. 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 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". 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. This is me now about crowns for hand tools. Not for magnetic drills and machines. Life has not spared the teeth of this crown and in some places they are chipped 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. Okay, let’s drop that. Is it worth taking them to Ali?
Thank you for your understanding. They are bimetallic because the material from which they are made is a combination of high speed steel and cobalt. Something may be wrong. They will be discussed in the review. Although she has done a lot of holes. 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.
Everything that will be written below may contain inaccuracies. The crown is all-metal, and only the center drill is removable. And this item is sold separately. And because there were no others. They are usually sold without a shank with a central drill. The crown cuts perfectly to this day. This means that the thickness of the “thick metal” is limited by this size. I have only one crown from that time. They look like this Here, for example, are photos from work when this crown was used But from experience, I can say that crowns with thick teeth of this type cut into metal more aggressively and cut through it faster. Further, in turn, they still differ in the shape of the "bowl" and the presence of spiral grooves for chip removal. In this connection, their total cost is quite decent. Large diameter drill, step or conical drill, and core drill (crown). I don’t have any tungsten carbide bits, but I could order them just for fun. Generally. I tried and had no problems. Here she is The author is a "krivoruk master" and an amateur. Why did you buy this one then? They just weren’t for sale. As I read somewhere, such crowns are positioned for drilling thick sheet metal. Back to news »