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Pin Hole Sizes

The document provides recommended hole sizes for pins and dowels, emphasizing the importance of following manufacturer guidelines while allowing for user discretion based on specific applications. It details the relationship between hole size and insertion force, highlighting that smaller holes may be beneficial in applications subject to vibration. Additionally, it outlines specific hole size tolerances for various types of pins and dowels, including considerations for interference fits in hardened and unhardened materials.

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106 views2 pages

Pin Hole Sizes

The document provides recommended hole sizes for pins and dowels, emphasizing the importance of following manufacturer guidelines while allowing for user discretion based on specific applications. It details the relationship between hole size and insertion force, highlighting that smaller holes may be beneficial in applications subject to vibration. Additionally, it outlines specific hole size tolerances for various types of pins and dowels, including considerations for interference fits in hardened and unhardened materials.

Uploaded by

PEDRO
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Recommended Hole Sizes

Pins and Dowels


It is important to follow the hole diameter instructions given by the various manufacturers and
standards organisations, and the data given below comes from these sources. However, the user
should decide, in the circumstances of a particular application, which hole size, within the permitted
tolerance range, to adopt, since this can effect the performance of the pin considerably.

The general principle is that the inserting pin or dowel requires significantly more force at the bottom
of the hole tolerance range than at the top. This has the following implications;-

• The higher insertion force require, the more difficult the assembly operation, and risk of damaging or
over-stressing the area of the material surrounding the hole

• The harder the pin is to insert, the more firmly it will stay in place so in applications where vibration is a
consideration, it may be worthwhile to use a minimum hole size

Recommended Hole Sizes for Spring Pins and Grooved Pins (figures in mm)

Diameter Coiled Pins Slotted Spring Pins Groove Pins


(all duties) (heavy or light duty)
MIN MAX MIN MAX MIN MAX
0.8 0.8 0.84 - - - -
1 1.00 1.04 1.00 1.10 1.000 1.025
1.2 1.20 1.24 - - 1.200 1.225
1.5 1.50 1.60 1.50 1.60 1.500 1.525
2 1.99 2.10 2.00 2.10 2.000 2.025
2.5 2.49 2.60 2.50 2.60 2.500 2.525
3 2.99 3.10 3.00 3.10 3.000 3.025
3.5 3.48 3.62 3.50 3.62 - -
4 3.98 4.12 4.00 4.12 4.000 4.075
4.5 - - 4.50 4.62 - -
5 4.95 5.12 5.00 5.12 5.000 5.075
6 5.95 6.13 6.00 6.12 6.000 6.075
7 - - 7.00 7.12 - -
8 7.93 8.17 8.00 8.15 8.000 8.090
10 9.93 10.20 10.00 10.15 10.000 10.090
11 - - 11.00 11.15 - -
12 11.90 12.22 12.00 12.17 12.000 12.110
13 - - 13.00 13.17 - -
14 - - 14.00 14.17 - -
15 - - 15.00 15.17 - -
16 15.85 16.25 16.00 16.17 16.000 16.110
18 - - 18.00 18.17 - -
20 19.85 20.25 20.00 20.17 - -

Recommended Hole Sizes for Dowels


Where an interference fit is required (as opposed to a sliding or clearance fit) the dowel must be
precision ground and the hole must be reamed.
The relationship between the diameter of the pin and the diameter of the hole must take into account
the ductility of the dowel and the hole material and will vary more accordingly to this factor than
according to the size of the dowel itself.

In hardened steel parts, the hole should be .005 to .008mm (5-8 microns) smaller than the dowel. In
unhardened material, the hole should be 0.025mm (25 microns) smaller than the dowel.

For dowels ground to m6 tolerance (Technifast standard type), the dowel diameters are as follows,
and holes should be reamed to 25 microns smaller (of 5-8 microns for hardened steel) using the
lower limit of the m6 range as the reference point;

Nominal Dowel Diameter


Diameter (m6)
0.8 0.802-0.808
1 1.002-1.008
1.5 1.502-1.508
2 2.002-2.008
2.5 2.502-2.508
3 3.002-3.008
4 4.004-4.012
5 5.004-5.012
6 6.004-6.012
8 8.006-8.015
10 10.006-10.015
12 12.007-12.018
14 14.007-14.018
16 16.007-16.018
20 20.008-20.021

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