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217 lines
7.4 KiB
ReStructuredText
217 lines
7.4 KiB
ReStructuredText
.. image:: docs/imgs/logo.png
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:alt: bolt-in-nut logo
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threadlib is a library of standard threads for `OpenSCAD <https://www.openscad.org>`__.
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It is based on Helges excellent
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`threadprofile.scad <https://github.com/MisterHW/IoP-satellite/tree/master/OpenSCAD%20bottle%20threads>`__
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to create nice threads with lead-in / lead-out tapers. Check out his `article on generating nice threads <https://hackaday.io/page/5252-generating-nice-threads-in-openscad>`__
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on Hackaday.
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In contrast to other thread libraries such as `openscad-threads <http://dkprojects.net/openscad-threads/>`__,
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`yet another thread library <https://www.thingiverse.com/thing:2277141>`__,
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`threads for screws and nuts V1 <https://www.thingiverse.com/thing:3131126>`__,
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and `threading.scad <https://www.thingiverse.com/thing:1659079>`__,
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threadlib does not make you look up diameters and pitches and maybe even
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thread-profiles in tables and norms: It has these tables built in.
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Creating a thread is as simple as
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.. code-block:: OpenSCAD
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use <threadlib/threadlib.scad>
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thread("G1/2-ext", turns=10);
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.. image:: docs/imgs/thread-G1o2-ext-10turns.png
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:alt: bolt-in-nut logo
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to create a British Standard Pipe parallel external thread.
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Why you may want to use threadlib
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==================================
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- really easy to use
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- creates nice threads
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- configurable higbee arc
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- creates working threads (clearances are left for production tolerances)
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- flexible:
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- choose the $fn you need to fit the rest of your design
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- let threadlib tell you the thread specs so you can do with them what *you* want
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- extensible: Add your own threads
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- tried and tested in the real world: Well, partly. Given the sheer number of
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threads, this is only possible with *your* help! Any feedback regarding working
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(or not working) threadlib-threads is appreciated.
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Installation
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===========================
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Prerequisits:
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- `scad-utils <https://github.com/openscad/scad-utils>`__
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- `list-comprehension <https://github.com/openscad/list-comprehension-demos>`__
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- `threadprofile.scad <https://github.com/MisterHW/IoP-satellite/blob/master/OpenSCAD%20bottle%20threads/thread_profile.scad>`__
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Save all of these into your OpenSCAD `library folder <https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Libraries>`__
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threadlib:
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Clone threadlib into the folder 'threadlib' inside your OpenSCAD library folder
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Your libraries folder should now look similar to this:
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::
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libraries
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├── list-comprehension-demos/
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├── scad-utils/
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├── thread_profile.scad
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└── threadlib/
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Usage
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===========================
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Before you start: threadlib is designed in millimeters (not meters, not inches).
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Make sure that your units are set accordingly or scale the output of threadlib
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to match the units you use in your project!
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To create a bolt (without head) with 5 turns of M4 thread:
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.. code-block:: OpenSCAD
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bolt("M4", turns=5, higbee_arc=30);
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.. image:: docs/imgs/bolt-M4.png
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:alt: Bolt with M4 thread
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See these nice lead-in / lead-out tapers? Try a nut (this time using the default
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argument for higbee_arc):
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.. code-block:: OpenSCAD
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nut("M12x0.5", turns=10, Douter=16);
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.. image:: docs/imgs/nut-M12x0.5.png
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:alt: M12x0.5 nut
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Note that for a nut you also have to specify an outer diameter. The inner
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diameter is implicitly given by the thread designator ("M12x0.5" in this case).
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To make a threaded hole (e.g. in a plate), an intuitive approach would be to
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create the difference of the plate and a bolt. However, this part would not work
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well in practice: You need a little space around the bolt to avoid collisions.
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threadlib's solution is to provide the tap module:
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.. code-block:: OpenSCAD
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tap("G1/2", turns=5);
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.. image:: docs/imgs/tap-G1o2.png
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:alt: G1/2 tap
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The tap shown above *is* intended for use like this and has accounted for the
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allowances needed in practice. Also, it will create the tapers:
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.. code-block:: OpenSCAD
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difference() {
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part_to_be_tapped_here();
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tap("G1/2", turns=5);
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}
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Make sure that the tap extends a tiny bit out of the part to be tapped.
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Otherwise, you will end up with infinitely thin artifacts covering the entrance
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of your tapped hole.
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If you only need the threads alone:
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.. code-block:: OpenSCAD
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thread("G1/2-ext", turns=5);
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.. image:: docs/imgs/thread-G1o2-ext.png
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:alt: G1/2 external thread
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(Note: You need to specify whether you want internal ("-int") or external
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("-ext") thread here.) Then, add the support you want. In the simplest
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case, a cylinder (which is what nut(...) uses):
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.. code-block:: OpenSCAD
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specs = thread_specs("G1/2-ext");
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P = specs[0]; Rrot = specs[1]; Dsupport = specs[2];
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section_profile = specs[3];
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H = (5 + 1) * P;
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translate([0, 0, -P / 2])
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cylinder(h=H, d=Dsupport, $fn=120);
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.. image:: docs/imgs/flexible.png
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:alt: G1/2 bolt
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Here, we have used the function thread_specs(...) to look up the threads
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specifications - including the recommended diameter of the support structure.
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List of supported threads
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===========================
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Currently, threadlib knows these threads:
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- Metric threads (coarse, fine, and super-fine pitches) M0.25 to M600.
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- Unified Inch Screw Threads (UNC, UNF, UNEF, 4-UN, 6-UN, 8-UN, 12-UN,
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16-UN, 20-UN, 28-UN, and 32-UN). All threads are class 2 threads.
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- `BSP parallel thread
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<https://www.amesweb.info/Screws/British-Standard-Pipe-Parallel-Thread-BSPP.aspx>`__
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G1/16 to G6. All threads are class A threads.
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- `PCO-1881
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<https://www.bevtech.org/assets/Committees/Packaging-Technology/20/3784253-20.pdf>`__
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(PET-bottle thread)
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Extensibility
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===========================
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Don't find some of the threads you need for your project? Don't worry: You can
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add your own:
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.. code-block:: OpenSCAD
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use <threadlib/threadlib.scad>
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MY_THREAD_TABLE = [
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["special", [pitch, Rrot, Dsupport,
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[[r0, z0], [r1, z1], ..., [rn, zn]]]]
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];
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thread("special", turns=15, table=MY_THREAD_TABLE);
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Care to share? Safe others from repeating the valuable work you have already
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accomplished and get the fame you deserve: Send in your tried and tested threads
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for addition to threadlib! See `Design of Threadlib <./docs/DesignOfThreadlib.md>`_
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for help on how to hack your own thread as shown above and
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`Creating Thread Specs <./docs/CreatingThreadSpecs.md>`_ for an introduction on how
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to contribute entire thread classes to threadlib.
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Still reading?
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===========================
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If you read this far, you're probably not here for the first time. If you
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use and like threadlib, would you consider giving it a Github Star? (The
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button is at the top of this website.)
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Change Log
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===========================
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- 0.4: `PCO-1810 <https://www.isbt.com/assets/Threadspecs/pco1810.pdf>`__.
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tap module. Fixes bug with $fn in straight_thread(). Lists metric
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threads under short designator and full designator.
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- 0.3: Unified Inch Screw Threads (UNC, UNF, UNEF, 4-UN, 6-UN, 8-UN, 12-UN,
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16-UN, 20-UN, 28-UN, and 32-UN. Fixed problem with PCO-1881-int. Fixed problem
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with G-ext threads. New build system.
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- 0.2: Metric threads, `PCO-1881 <https://www.bevtech.org/assets/Committees/Packaging-Technology/20/3784253-20.pdf>`__
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- 0.1: Initial release supporting `BSP parallel thread <https://www.amesweb.info/Screws/British-Standard-Pipe-Parallel-Thread-BSPP.aspx>`__
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