2012年4月23日 · Let’s now explain how screw threads are designated in metric. The closest size screw in metric to a #4-40 machine screw is M3. What does M3 mean? Well, the M means metric and the 3 means three millimeters in diameter.

2021年1月29日 · You asked about M3, M4, etc - that describes (only) the outside diameter of the screw - or the size of an unthreaded hole the screw would slip through. A full description is like M6-1X25 Which describes the outer diameter (6) , the distance from one thread to the next (1) (pitch) and the length (25) (all in millimeters.)

牙孔直径为2.845mm 注解：4-40UNC A. 4是指美制螺纹4号(0.112英寸）即2.845mm B. 40是指1英寸中有40个牙数的螺纹，即牙距为25.4/40=0.635 C. UNC代表美制粗牙螺纹 已赞过 已踩过

Inch thread (UNC) vs. Metric Thread (M3) Conversion data for UNC to metric fasteners for industrial bolts and machine screws. While metric screws and inch screws may appear similar, they possess different thread types and fundamental units.

According to the formula, a #4 screw has a diameter of 0.112′′. The closest fractional size is 0.125′′, which is a 1/8 inch drill bit. M3 is the closest metric screw to a #4-40 machine screw. What size is 4 40 in mm in this case?

2016年2月11日 · Try a test using a thin piece of aluminum. Drill and tap for 4-40 and then try it both ways with the M3 tap.

#4 - 40 UNC : Basic Thread Dimensions (Pitch, minor & major diameters, depth, lead), Tolerance range for all applicable classes and much more

Below is a single, consolidated reference for comparing common metric diameters or lengths (in mm) with their approximate inch equivalents (“in.”) and the closest common fraction typically used by mechanics. If you see a fastener labeled “M6,” that simply refers to 6 mm.

Metric bolt conversion data for industrial bolts/rods, machine screws and small diameter fasteners includes metric to standard bolt conversions. The chart below shows metric bolt conversions and DIN numbers for fasteners.

M3*0.5 螺丝是否等同于UNC4-40?不同标准螺纹当然是不能互选的。 UN是在美国国家螺纹标准（N）基础上演变的统一螺纹。 Nr.4-40 UNC-2B是统一粗牙螺纹，代号是4，每英寸40牙，公差带是2B。