For the teeth of M20 1, it is most appropriate to make a hole and how deep the tooth should be if th

Don't worry too much.

The timing of a child's teething is mainly determined by genetic factors. Usually children begin to erupt at 6 to 7 months of age, early teething children begin to erupt at 4 months, late teething children do not erupt until about 10 months, and individual children do not erupt until 1 year old before the first baby tooth erupts, which is related to the speed of bone growth in infancy. What are the symptoms of teething:

Late teething means that the child's bones grow more slowly, and early teething means that the child's bones grow faster, which is of course relative. As long as it is not due to calcium deficiency or disease, late teething will generally not affect the growth and development of bones in the future. The growth of a child is mainly due to the growth of long bones (limb bones), and the growth of long bones is mainly carried out in the metaphysis at both ends of the diaphysis and in the cartilage tissue between the epiphysis.

As we age, the long bones of the limbs grow much faster than the trunk, and by the end of adolescence, the bones stop growing and the child will not grow taller. The child's future height is determined by genetics, nutrition and appropriate exercise, and is not directly related to the time of teething. Some parents think that their children are deficient in calcium when they see that they are not teething when they should teeth, so they give their children cod liver oil and calcium tablets, which is not advisable.

Whether to give calcium to the child or not, mainly according to the actual situation of the child's body to decide, the child teething late is not necessarily a calcium deficiency, but to be combined with the examination and the symptoms of a comprehensive analysis to decide. Children with calcium deficiency often manifests as slow fontanelle closure, thin hair, excessive sweating, crying, etc., at this time, under the guidance of the doctor, appropriately supplement some calcium preparations and cod liver oil drops, and pay attention to the reasonable complementary food, which is beneficial to the child's health. If the child has not teethed at 8 months or 10 months, parents give the child a large amount of cod liver oil and calcium tablets, which can easily cause vitamin D overdose or even poisoning, which is harmful to the child's health.

The bottom hole of M12 is the diameter.

1. Diameter.

2. M2: diameter.

3. M3: diameter.

4. M4: diameter.

5. M5: diameter.

6. M6: diameter 5

7. M8: diameter.

8. M10: diameter.

9. M14: diameter 12

10, M16: straight head call diameter 14

Expand the information is expectedThe diameter of the bottom hole can be found in the manual or calculated according to the following empirical formula:

1. Brittle materials (cast iron, bronze, etc.): drilling diameter d0=d (thread outer diameter) pitch) 2. Plastic materials (steel, copper, etc.): drilling diameter d0=d (thread outer diameter) - p (pitch) tap In the process of tapping threads, the cutting edge is mainly to cut metal, but there is also the effect of squeezing metal, which causes the metal to bulge and flow to the tooth tip, so before tapping, the hole diameter (that is, the bottom hole) should be greater than the inner diameter of the thread.

When tapping the thread of the blind hole (the one shoots the hole but does not pass through the hole), the depth of the hole should be greater than the length of the thread because the tap cannot be tapped.

1. Calculation method of metric thread:

Base diameter = large diameter pitch.

2. Calculation method of inch thread:

Base diameter = large diameter pitch.

M20 means common thread with a nominal diameter of 20mm.

In the standard thread marking method specified in the national standard, the first letter represents the thread code, for example: M represents the ordinary thread, G represents the pipe thread that is not threaded sealed, R represents the pipe thread sealed with thread, TR represents the trapezoidal thread, etc.

The second number indicates the nominal diameter of the thread, which is the greater diameter of the thread. It represents the maximum diameter of the thread in millimeters. The symbols after that are pitch, lead, rotation, mid-diameter tolerance code, top diameter tolerance code, and screw-length side code.

The threaded stove of M20 2 should drill 18 holes. From the National Chain Department standard "GB T 20330-2006 Diameter of twist drill for hidden shed drilled before tapping", see the figure below

The M20 hole is 30 deep, and the thread is about 40mm deep.

How deep it is depends on how deep the screws are to be screwed in, or try to hit as deep as possible, it's better than shallow, right? Either play 2 times the diameter and 40 deep according to the normal unmarked. Generally, the thread length is a multiple of the thread diameter, that is, the minimum is 30mm.

Types of threads: Threads formed along one helix are called single-wire threads, and threads formed by two or more helix-lines distributed equally along the axial direction are called multi-wire threads. The thread that is screwed in when rotated clockwise is called a right-handed thread; The thread that is screwed in when rotated counterclockwise is called a left-handed thread.

Ordinary threads are the most widely used, and the threads on threaded fasteners (bolts, studs, screws, nuts, etc.) are generally ordinary threads.

The bottom hole is machined with a drill bit. Bottom hole range:.

Ordinary threads are divided into coarse teeth and fine teeth, and the same nominal diameter can have a variety of pitches, among which the largest thread length is called coarse threads, and the rest are fine threads.

Coarse teeth: do not need to mark the pitch, such as M8, M12 6H, M16 7H, etc., mainly used for coupling threads, compared with fine threads, because of the large pitch, the thread lifting angle is also large, the self-locking performance is poor, generally used with spring washers: the pitch is large, the tooth profile is also deep, and the strength of the body is also greatly reduced.

The advantage is that it is easy to disassemble and assemble, and the standard parts supporting it are complete and easy to interchange.

M20 thread, standard pitch, small diameter, theoretically the bottom hole can be punched, but in practice, the general drilling.

The inner base hole of M20*2 can be punched with a diameter of 18.

Threaded tapping bottom hole: nominal diameter x. Both 17 or so.

Thread:

It is a graphic composed of line types, and there are many types of it. The most intuitive is the spiral protrusion with a specific cross-section made on the surface of a cylinder or conical matrix.

Thread classification:According to its parent shape, it is divided into cylindrical thread and tapered thread.

According to its position in the matrix, it is divided into external thread and internal thread.

According to its cross-sectional shape, it is divided into triangular thread, rectangular thread, trapezoidal thread, zigzag thread and other special shape threads.

According to the direction of the helix, it is divided into left-handed thread and right-handed thread, and the right-handed thread is generally divided into single-wire thread, double-wire thread and multi-wire thread connection according to the number of spiral wires, and the transmission is used with double or multi-wire.

According to the size of the tooth, it is divided into coarse thread and fine thread.

According to different occasions and functions, it can be divided into fastening threads, pipe threads, transmission threads, special threads, etc.