Cheap step drills 3-12mm, 4-12mm, 4-20mm. Are they good for anything?

Why in thin-walled? Because the shape of this drill is a stepped cone and if the thickness of the part is greater than the height of one step of the drill (in this case from 4 to 7 mm), then instead of an even hole of the same diameter, we will get a conical hole.
A drill of 4-20 mm already has 9 of them with a step of 2 mm.
Included are 3 drills of different sizes. 3-12mm: 260-400 turns I won’t even try on steel plates, since even aluminum has blunted it. But such a hole is easier to make with a drill of the desired diameter or a crown.
The polyethylene is soft, the drill bites into it without problems, cutting chips
Let’s check the selective correspondence of the actual diameter steps of its face value. It drills perfectly, only Shurik puffs up, is rather weak.
Inside there is a fabric case with Velcro drills and small instruction I took them for drilling plastic, so let’s start with it. One wetting was not enough, repeat. The hole is drilled in one step.

Cheap step drills 3-12mm, 4-12mm, 4-20mm. Not critical.
On the product page, however, they admonish that the drill is good for many things: When using this type of cutting tool, it is much easier to control the size of the hole being machined and its diameter will strictly correspond to one of the diameters of the consecutive row of drills.
The hole is 9 mm in diameter. We drill one more hole and stop at the 10th diameter. 4-20mm: 180-240 turns Pre-drilling with a smaller diameter or punching is usually not required In hard plastic, the hole is quite neat and round. Each drill has its own number of steps. Drilling metals with these drills is not The seller left this recommendation for drilling metals: "Injection of cooling water during operation, it can effectively extend the life of the drill, especially in the case of continuous drilling." Turnovers should be kept low. The main purpose of such a step drill is to make holes in sheet or thin-walled material: plastic, wood, drywall, metal, etc.
The product is delivered in a small paper envelope
The tip of each drill has sharpening. Wet the drill bit in some water and let’s get started
Inclined transition between steps 1-2 mm.
A 4-12 mm drill has only 5 of them in 2 mm increments.
Let’s check that the specified diameter corresponds to the actual size of the hole.
3-12 mm drill 2 tenths of a mm short
Well, the limit of the abilities of these particular drills is 2 mm thick aluminum sheet. We must keep this in mind Fast, smooth, accurate.
The drills are in a case in individual pockets There is a yellow coating on the drills, the seller positions it as titanium.
On a 4-12 mm drill, this step is maintained exactly – 10 mm Summing up: plastic, wood, plywood, etc. no problem. Step drills got their name due to the successive stepped transitions of diameters. After that, the drill became bad at drilling even plastic. A rather smooth transition from one step to another forms a chamfer for a pre-drilled hole The total length of the cutting part of the drill is 50 mm with a step height of 4 mm. The hole is round, only there are a few scratches around the edges. It is especially convenient to work with such a drill when you need to simultaneously make holes of different diameters.
At the center there is a shallow hole with a diameter of 2 mm Unless of course we do not need a hole of the largest diameter that this drill has.
The hole turns out to be quite even, neat, although not perfect Not for hardening” In this case, the time for removing and installing drills of different diameters is significantly saved.
Standard hexagon shank with a groove Are they good for anything?

The 3-12 mm drill has the largest number of steps – 10 with a step of 1 mm.
For the next test, I changed the cordless screwdriver to the mains one, it is more powerful, ideally, of course, such a drill should be used with a drill, but I don’t have it at hand now. This is unlikely, titanium has a silvery-white color. The product page says:
But the drill has already deteriorated even after aluminum: the tip and the edge of the transition to the second step have become dull. 4-12mm: 260-400 turns The total length of the cutting part of the drill is 46 mm with a step height of 5 mm. Please note that stainless steel and spring steel are not applicable.
This is how polyethylene chips are cut Take for example 10 diameter on each drill. "Suitable material: Workpieces with general hardness, such as wood, plastic, PVC plate, iron plate, plate thickness within 3 mm. A step drill is a cone-shaped drill with one or more longitudinal straight or spiral grooves that form the cutting edge. This is how the hole turns out – round, but with scuffs In this set, these are diameters in the range of 3-12 mm, 4-12 mm, 4-20 mm
9 mm plywood.
The transition from size to size when drilling is clearly visible and it will not be difficult to achieve the desired diameter Also no problem Wooden block 35 mm thick.
Let’s take a plastic that is harder and thicker than 3 mm. Then things got harder, but the weak link was not a drill The second step went faster Let’s check the drills in operation. />On a 4-20 mm drill, three tenths of a mm were not enough to the declared size
Each step of the drill is marked with its diameter.
Instruction in Russian
language, and good Russian, and even with some comments either from the seller or the translator
Overall, quite acceptable. The total length of the cutting part of the drill is 40 mm with a step height of 7 mm. I need to equip the polyethylene lid of the jar with fittings like this This is how a cone hole turns out in three-dimensional parts
We mark the installation locations on the lid, select the right drill and take a screwdriver in our hands

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