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I created an Eagle part that has several holes to solder 0.1" pitched break away male headers to, such as the one below.

However the pad has a hole thats too narrow for the header! What drill size should be used? I used the default of 0.03149606

enter image description here

enter image description here

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  • \$\begingroup\$ What does the vendor say? \$\endgroup\$ Commented Dec 7, 2014 at 1:55
  • \$\begingroup\$ @IgnacioVazquez-Abrams I can find the pitch and mating post length, but not the diameter of the mating post. Is there a standard diameter for these? \$\endgroup\$
    – Nyxynyx
    Commented Dec 7, 2014 at 1:58
  • \$\begingroup\$ Did you see the "Recommended Hole Pattern" in the drawing linked to on that page? \$\endgroup\$ Commented Dec 7, 2014 at 2:02
  • \$\begingroup\$ Doesn't Eagle have a bunch of male header parts already in it? \$\endgroup\$
    – Passerby
    Commented Dec 7, 2014 at 3:07
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    \$\begingroup\$ @IgnacioVazquez-Abrams Vendor probably says "孔必须足够大,并不能太小" :) \$\endgroup\$
    – Kamil
    Commented Dec 7, 2014 at 6:19

4 Answers 4

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SparkFun has an Eagle library that has pads for single and dual row 0.1" headers from 1 to 40 pins. Here is one of several 1x03 headers (single row, three pins):

enter image description here

The holes have a 40 mil diameter. The yellow square posts, which are for reference only, are drawn with 20 mil sides instead of the standard 25 mils, but expanding the sides out to 25 mils and then measuring the distance from the corners to the edge of the hole shows a 3 mil clearance.

Their library SparkFun.lbr can be downloaded here. It works with both version 5 and version 6 (I haven't tried it on version 7 yet). They also have a set of libraries in the new XML format (version 6 and later) here.

As swebere has pointed out, single and double row headers are also available in some of the libraries whhich are installed with Eagle, such as pinhead. Here is a single row 1x03 header with long pads:

enter image description here

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    \$\begingroup\$ Why an external library? The buiild-in pinhead.lbr already has single/dual row headers. In addition, it uses long pads, for single row headers, which gives a bit more stability. \$\endgroup\$
    – sweber
    Commented Dec 7, 2014 at 17:28
  • \$\begingroup\$ @sweber yep, I've used those too, I just happen to like the SparkFun versions. But good to point out. \$\endgroup\$
    – tcrosley
    Commented Dec 7, 2014 at 17:35
  • \$\begingroup\$ @sweber What are long pads? \$\endgroup\$
    – Nyxynyx
    Commented Dec 7, 2014 at 17:59
  • \$\begingroup\$ @Nyxynyx I updated my answer to include the long pad headers. \$\endgroup\$
    – tcrosley
    Commented Dec 7, 2014 at 18:05
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The pins in the common 0.1" post headers are .025" square.

For .025" square posts, I usually specified .040" finished hole size (size after plating). For square posts, the hole must be slightly larger than the diagonal measurement of the post.

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    \$\begingroup\$ Ditto. For 20+ years, my default hole size for 0.1" spacing headers has been 0.040 if I have to make the hole manually. \$\endgroup\$
    – lyndon
    Commented Dec 7, 2014 at 22:01
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Did this up graphically for ref, and for 50-mil calcs. Using the .040" hole for the .025" yields a radial-clearance of ~.0023", see below.

-enter image description here

Note the dimensions are x10 here, makes for a clearer picture to illustrate.

If interested, this yields a 0.0273" hole for a 50-mil header, a 0.7mm drill seems best here.

Example Headers (for calcs):

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use 1mm (0.040") finished size of a loose fit, or 0.9mm (0.035") for a close fit

as you have discovered 0.8mm is too small but you may be able to press the pins in or file them down to fit.

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