CNC Knowledge: Commonly used CNC machining calculation formulas and most comprehensive thread standards

international standards

1. Formula for calculating the inner hole diameter of thread extrusion tapping:

Formula: Tooth outer diameter – 1/2 x distance between teeth

Example 1: Formula: M3×0.5=3-(1/2×0.5)=2.75 mm

M6×1.0＝6－(1/2×1.0)＝5.5mm

Example 2: Formula: M3×0.5=3-(0.5÷2)=2.75 mm

M6×1.0＝6－(1.0÷2)＝5.5mm

2. Conversion formula for general UK wiretapping:

1 inch = 25.4 mm (code)

Example 1: (1/4-30)

1/4×25.4＝6.35 (tooth diameter)

25.4÷30＝0.846 (tooth distance)

Then 1/4-30 converted to metric teeth should be: M6.35×0.846

Example 2: (3/16-32)

3/16 × 25.4＝4.76 (tooth diameter)

25.4÷32＝0.79 (tooth distance)

Then 3/16-32 converted to metric teeth should be: M4.76×0.79

3. The general formula for converting British teeth to metric teeth:

Numerator ÷ denominator × 25.4 = tooth outer diameter (same as above)

Example 1: (3/8-24)

3÷8×25.4=9.525 (outer diameter of the tooth)

25.4÷24＝1.058 (metric pitch)

Then 3/8-24 converted to metric teeth should be: M9.525×1.058

4. The formula to convert American teeth to metric teeth:

Example: 6-32

6-32 (0.06+0.013)/code×6＝0.138

0.138 × 25.4 = 3.505 (outer diameter of tusk)

25.4÷32＝0.635 (tooth distance)

Then 6-32 converted to metric teeth should be: M3.505×0.635

1. Formula for calculating the inner diameter of the hole:

The outer diameter of the tooth – 1/2 × the pitch of the tooth must be:

M3.505－1/2×0.635＝3.19

Then the inner diameter of 6-32 should be 3.19

2. Extrusion thread tapping inner hole algorithm:

Simple calculation formula for the bottom diameter of hole 1:

Tooth outer diameter – (tooth pitch × 0.4250.475)/code = bottom hole diameter

Example 1: M6×1.0

M6-(1.0×0.425)=5.575 (maximum bottom opening)

M6-(1.0×0.475)＝5.525 (minimum)

Example 2: Simple formula for calculating the inside diameter of the hole tapped by the cutting wire:

M6－(1.0×0.85)=5.15 (maximum)

M6－(1.0×0.95)＝5.05 (minimum)

M6－(tooth pitch × 0.860.96)/code = bottom opening

Example 3: M6×1.0=6−1.0=5.0+0.05=5.05

5. Simple formula to calculate the outside diameter of press teeth:

1. Diameter – 0.01 × 0.645 × pitch (need to pass and stop)

Example 1: M3×0.5＝3-0.01×0.645×0.5＝2.58 (outer diameter)

Example 2: M6×1.0＝6-0.1×0.645×1.0＝5.25 (outer diameter)

6. Metric tooth bearing diameter calculation formula: (Complete tooth calculation)

Example 1: M3×0.5＝3-0.6495×0.5＝2.68 (outer diameter before turning)

Example 2: M6×1.0＝6-0.6495×1.0＝5.35 (outer diameter before turning)

7. Depth of embossed outer diameter (outer diameter)

Outer diameter ÷ 25.4 × Tooth pitch = Outer diameter before embossing

Example: 4.1÷25.4×0.8 (no flower)=0.13 Embossing depth should be 0.13

8. Diagonal conversion formula for polygonal materials:

1. Square: diagonal diameter × 1.414 = diagonal diameter

2. Pentagon: Diagonal diameter × 1.2361 = Diagonal diameter

3. Hexagon: Diameter of opposite sides × 1.1547 = Diameter of opposite corners

Formula 2: 1. Four corners: diagonal diameter ÷ 0.71 = diagonal diameter

2. Hexagon: diagonal diameter ÷ 0.866 = diagonal diameter

9. Tool thickness (cutting knife):

Outer diameter of material ÷ 10 + 0.7 reference value

10. Formula for calculating taper:

Formula 1: (Large head diameter – Small head diameter) ÷ (2 × total cone length) = Degrees

Is equal to find the value of the trigonometric function

Formula 2: Simple

(Large head diameter – Small head diameter) ÷ 28.7 ÷ Total length = Degrees

The most complete thread standard

UNC: unified coarse thread

5/16: Nominal thread size in inches

18: The pitch is 1/18, or 18 teeth per inch

3A: tolerance level, level three, external thread (B is internal thread)

HR: right rotation

What is the difference between common thread and inch thread?

Metric threads are expressed by pitch, and American and British threads are expressed by the number of threads per inch. This is their biggest difference. Metric threads have a 60 degree equilateral profile, British threads have a 55 degree isosceles profile and American threads have a 55 degree isosceles profile. 60 degrees. Metric threads use metric units, while American and British threads use imperial units. Pipe threads are mainly used to connect pipes. Internal and external threads are closely matched, and there are two types: straight pipes and tapered pipes. Nominal diameter refers to the diameter of the connected pipe. Obviously, the main diameter of the thread is greater than the nominal diameter. 1/4, 1/2, 1/8 are the nominal diameters of the threads in inches, in inches

The best way is to measure the distance between the two points of the thread. If it is a whole or decimal number divisible by 5, it is a metric thread. For example: 1MM 1.5MM 1.75MM 2MM 2.5MM 3MM 3.5MM 4MM. ””” ”

Imperial thread cone problem

1. BSP is British pipe thread.

However, there is BSP.Tr., BSP.PI. and BSP.F.

BSP.Tr. is a tapered pipe thread used to seal joints. BSP.PI. is a parallel pipe thread, used to seal joints. It has internal threads only and mates with the external threads of BSP.Tr. BSP.F. is a parallel pipe thread, used for general joints.

Just because you know the BSP doesn’t mean you can’t deal with it randomly. It is best to confirm in detail. Otherwise there will be an oil or gas leak and we will have big problems.

2. G thread and BSPP thread

Likewise, these are all British cylindrical pipe thread codes and the profile angle is 55 degrees.

3. How many types of British thread are there? What are the characteristics and representation of BSP threads?

Two types, BSPP (pipe thread) and BSPT (55 degree tapered pipe thread, opposite to American 60 degree NPT tapered pipe thread and incompatible with each other)

4. Comparing G thread and Rp thread, which parts are the same and which parts are different? Is there a difference in usage between the two?

Both the G thread and the Rp thread are 55° cylindrical threads. It’s just that different countries (organizations) have different code names.

G is the code name for China, France, the former Soviet Union and Japan;

PF is the code name for Japan;

BSP and BSPP are the UK code names;

R and K are German codes (R is internal thread, K is external thread);

TPYБ is the code name for the former Soviet Union;

Rp is the code name of ISO.

5. What is the difference between 1/8 and NPT1/8 threads?

They should all be national standards now, but the old NPT standard is called Z, which is 60 degree sealed tapered pipe thread, national standard number GB/T12716-2002M, and G is threadless thread at 55 degrees. sealed cylindrical pipe thread, national standard number GB/T3707-2001

6. Is the English code for British standard pipe thread BSP? Does it have a cone?

Code should be G, cylindrical pipe thread, no cone

7. Rp thread and G thread both represent cylindrical pipe threads. What is the difference between the two?

Also: what is the difference between Rp and Rb, and can they be used in place of each other.

pipe thread

Unsealed internal and external pipe threads, characteristic code is G.

G1/2 indicates a cylindrical internal pipe thread;

G1/2A represents the cylindrical external thread of the pipe.

Pipe threads for thread sealing.

Rp——indicates a cylindrical internal pipe thread;

Rc——represents the tapered internal thread of the pipe;

R——Indicates the tapered external pipe thread.

Example wire code:

G1/2-LH represents an unsealed left-hand internal thread, with a size code of 1/2 inch.

RP and RB cannot be used interchangeably

Because one has teeth at 55 degrees and the other has teeth at 60 degrees.

Are “imperial thread” and “pipe thread” the same thing? ?

ZG is the first letter of Chinese pinyin for conical tube. This means a tapered pipe thread. 3/4 equals three-quarters of an inch. This means the inside diameter of the pipe is 3/4 inch.

To be precise, its inner diameter is 19.05mm, but this is an old standard that is no longer used. The current national standard stipulates that the inner diameter of ZG3/4″ thread is 20mm.

Its representation method should be: ZG3/4″. Among them (″) is the symbol representing thumbs.

One inch equals 25.4 millimeters. One inch equals 8 cents. The origin of 3/4 is 6/8=3/4. Commonly called 6 points.

Likewise, the inner diameter of the pipe with ZG1/2″ thread is ≈ 15 mm. It is commonly called 4 points.

The inner diameter of the pipe with ZG1″ thread is ≈ 25 mm. Commonly called 1 inch.

The inner diameter of the pipe with ZG11/2″ thread is ≈32 mm. Commonly referred to as 1 1/2 inch.

Tapered pipe threads are only used for hydraulic system connections; while G3/4″ pipe threads are only used for water pipe connections. Tapered pipe threads are very similar to pipe threads, the difference is only in the taper.

The pipe threads are all British! ! ! ! !