Through hole

Left two metal sheets with through-hole, screw and nut.
Right one with through-hole (above) and one with core hole (blind hole with internal thread , below) and screw

Two thin sheets and one thick one with a through hole each. They are held together by a rivet .

A through hole or a through hole is a hole through a component with the purpose of being able to carry out a screw , a rivet or a bolt . It differs from the blind hole , which does not extend to the back of the component.

In the standards (e.g. DIN 75) the hole diameters corresponding to the screw diameters are specified. In addition to the preferred “middle” row, there are also the “fine” and “coarse” rows, each with a slightly smaller or larger diameter. If you choose the "coarse" row, assembly is made easier and / or manufacturing errors are less of a hindrance (holes lying one above the other are not coaxial ).

A continuous or blind hole into which an internal thread for a screw is to be cut is called a core hole .

Through holes for metric screws

thread	fine [mm]	medium [mm]	coarse [mm]
M1	1.1	1.2	1.3
M1.2	1.3	1.4	1.5
M1.4	1.5	1.6	1.8
M1.6	1.7	1.8	2
M1.8	2	2.1	2.2
M2	2.2	2.4	2.6
M2.5	2.7	2.9	3.1
M3	3.2	3.4	3.6
M3.5	3.7	3.9	4.2
M4	4.3	4.5	4.8
M5	5.3	5.5	5.8
M6	6.4	6.6	7th
M8	8.4	9	10
M10	10.5	11	12
M12	13	13.5	14.5
M14	15th	15.5	16.5
M16	17th	17.5	18.5
M18	19th	20th	21st
M20	21st	22nd	24
M22	23	24	26th
M24	25th	26th	28
M27	28	30th	32
M30	31	33	35
M36	37	39	42
M42	43	45	48
M48	50	52	56
M56	58	62	66
M64	66	70	74

Literature and individual references

• Schönherr: Machining , Oldenbourg, 2002, p. 146.
• Europa-Lehrmittel (Ed.): Table book metal , 45th edition, pp. 78, 84 (illustration of holes)
• Tschätsch: Praxis der Zerspantechnik , Vieweg, 7th edition, p. 94

1. ↑ table metric thread DIN ISO . In: CNC & CNC milling machine - PreciFast.de . ( precifast.de [accessed June 14, 2018]).