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screws.scad
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//////////////////////////////////////////////////////////////////////
// LibFile: screws.scad
// Functions and modules for creating metric (ISO) and English (UTS) standard screws and nuts.
// Included is a function for calculating the standard dimensions of screws including the
// tolerance values that are required to make screws mate properly when they are formed
// precisely. If you can fabricate objects accurately then the modeled screws will mate
// with standard hardware without the need to introduce extra gaps for clearance.
// Includes:
// include <BOSL2/std.scad>
// include <BOSL2/screws.scad>
// FileGroup: Threaded Parts
// FileSummary: ISO (metric) and UTS screws and nuts.
//////////////////////////////////////////////////////////////////////
include <structs.scad>
include <threading.scad>
include <screw_drive.scad>
// Section: Screw and Nut Parameters
// This modules in this file create standard ISO (metric) and UTS (English) threaded screws.
// The {{screw()}} and {{nut()}} modules produce
// screws and nuts that comply with the relevant ISO and ASME standards,
// including tolerances for screw fit. You can also create screws with
// various head types and drive types that should match standard hardware.
// Subsection: Screw Naming
// You can specify screws using a string that specifies the screw.
// For ISO (metric) screws the specification has the form: "M`<size>`x`<pitch>`,`<length>`,
// so "M6x1,10" specifies a 6mm diameter screw with a thread pitch of 1mm and length of 10mm.
// You can omit the pitch or length, e.g. "M6x1", or "M6,10", or just "M6".
// .
// For UTS (English) screws the specification has the form `<size>`-`<threadcount>`,`<length>`, e.g.
// "#8-32,1/2", or "1/4-20,1". The units are in inches, including the length. Size can be a
// number from 0 to 12 with or without a leading # to specify a screw gauge size, or any other
// value to specify a diameter in inches, either as a float or a fraction, so "0.5-13" and
// "1/2-13" are equivalent. To force interpretation of the value as inches add '' (two
// single-quotes) to the end, e.g. "1''-4" is a one inch screw and "1-80" is a very small
// 1-gauge screw. The pitch is specified using a thread count, the number of threads per inch.
// As with the ISO screws, you can omit the pitch or length and specify "#6-32", "#6,3/4", or simply #6.
// Subsection: Standard Screw Pitch
// If you omit the pitch when specifying a screw or nut then the library supplies a standard screw pitch based
// on the screw diameter. For each screw diameter, multiple standard pitches are possible.
// The available thread pitch types are different for ISO and UTS:
// .
// | ISO | UTS |
// | -------- | -------- |
// | "coarse" | "coarse" or "UNC" |
// | "fine" | "fine" or "UNF" |
// | "extrafine" or "extra fine" | "extrafine", "extra fine", or "UNEF" |
// | "superfine" or "super fine" | |
// | "none" | "none" |
// .
// The default pitch selection is "coarse". Note that this selection is case insensitive.
// To set the pitch using these pitch strings you use the `thread=` argument to the modules.
// You cannot incorporate a named pitch into the thread name. The finer pitch categories
// are defined only for larger screw diameters. You can also use the `thread=` argument to
// directly specify a pitch, so `thread=2` produces a thread pitch of 2mm. Setting the
// pitch to zero produces an unthreaded screws, the same as setting it to "none". Specifying
// a numeric value this way overrides a value given in the specification. You can also set
// `thread=true` or `thread=false` to turn threading on and off, with the same default coarse
// threading when you set it to true.
// Subsection: Screw Heads
// By default screws do not have heads.
// You can request a screw head using `head=` parameter to specify the desired head type. If you want the
// head to have a recess for driving the screw you must also specify a drive type using `drive=`.
// The table below lists the head options. Only some combinations of head and drive
// type are supported. Different sized flat heads exist for the same screw type.
// Sometimes this depends on the type of recess. If you specify "flat" then the size will be chosen
// appropriately for the recess you specify.
// .
// The `drive=` argument can be set to "none", "hex", "slot",
// "phillips", "ph0" to "ph4" (for phillips of the specified size), "torx" or
// "t<size>" (for Torx at a specified size, e.g. "t20"). If you have no head but still
// give a drive type you will get a set screw. The table below lists all of the head types and
// shows which drive type is compatible with each head types. Different head types work in ISO and UTS,
// as marked in the first column.
// .
// |ISO|UTS|Head | Drive |
// |---|---|--------------- | ----------------------------|
// |X|X|"none" | hex, torx, slot |
// |X|X|"hex" | *none*|
// |X|X|"socket" | hex, torx|
// |X|X|"button" | hex, torx|
// |X|X|"flat" | slot, phillips, hex, torx|
// |X|X|"flat sharp" | slot, phillips, hex, torx|
// | |X|"flat small" | slot, phillips|
// | |X|"flat large" | hex, torx |
// | |X|"flat undercut" | slot, phillips |
// | |X|"flat 82" | slot, phillips |
// | |X|"flat 100" | slot, phillips |
// | |X|"round" | slot, phillips |
// | |X|"fillister" | slot, phillips |
// |X|X|"pan" | slot, phillips, torx (ISO only) |
// |X| |"cheese" | slot, phillips, torx |
// .
// The drive size is specified appropriately for the drive type: drive number for phillips or torx,
// and recess width in mm or inches (as appropriate) for hex. Drive size is determined automatically
// from the screw size, but by passing the `drive_size=` argument you can override the default, or
// in cases where no default exists you can specify it. Flat head screws have variations such as 100 degree
// angle for UTS, or undercut heads. You can also request a "sharp" screw which will set the screw diameter
// the theoretical maximum and produce sharp corners instead of a flat edge on the head. For a flat head screw
// the drive specification must start with "flat", but the flat head options
// can be mixed in any order, for example, "flat sharp undercut" or "flat undercut sharp".
// Subsection: Nuts
// Nuts come in standard sizes and BOSL2 has tables to produce sizes for both Imperial and metric nuts.
// A nut for a given thread size is defined by its shape, width and thickness. The shape is either "hex"
// for hexagonal nuts or "square" for square nuts. For hexagonal Imperial nuts, you can choose from thickness values
// of "thin", "normal" or "thick", but the thin and thick nuts are defined only for thread sizes of 1/4 inch and above.
// .
// Metric nut standards are more complicated because ISO has a series of standards and DIN has a series of conflicting
// standards. Nuts from McMaster-Carr in the USA comply with DIN rather than ISO. Furthermore, ISO does not appear
// to specify dimensions for square nuts. For metric nuts you can specify "thin", "normal" and "thick" and the
// nut will be constructed to ISO standards (ISO 4035, ISO 4032, and ISO 4033 respectively). The DIN standard for thin
// nuts matches ISO, but the DIN normal thickness nuts are thinner than ISO nuts. You can request DIN nuts
// by specifying a thickness of "DIN" or "undersized". If you request a square nut it necessariliy derives from DIN
// instead of ISO. For most nut sizes, the nut widths match between ISO and DIN, but they do differ for M10, M12, M14 and M22.
// .
// You can of course specify nuts by giving an explicit numerical width and thickness in millimeters.
// Subsection: Tolerance
// Without tolerance requirements, screws would not fit together. The screw standards specify a
// nominal size, but the tolerance determines a range of allowed sizes based on that nominal size.
// So for example, an M10 screw with the default tolerance has an outside (major) diameter between 9.74 mm and 9.97 mm.
// The library will use the center point in the allowed range and create a screw with a diameter of 9.86 mm.
// A M10 nut at the default tolerance has a major diameter (which is the inside diameter) between 10 mm and 10.4 mm.
// Shrinking the major diameter of a screw makes the screw loose. Shrinking the major diameter of a nut, on the other hand,
// makes the hole smaller and hence makes the nut tighter. For this reason, we need a difference tolerance
// for a screw than for a nut. Screw tolerances shrink the diameter to make the screw looser whereas nut tolerances
// increase the diameter to make the nut looser. Screws modeled using this library will have dimensions consistent with the
// standards they are based on, so that they will interface properly if fabricated by an accurate method. The ISO and UTS
// systems use different tolerance designations.
// .
// For UTS screw threads the tolerance is one of "1A", "2A" or "3A", in
// order of increasing tightness. The default tolerance is "2A", which
// is the general standard for manufactured bolts.
// .
// For UTS nut threads, the tolerance is one of "1B", "2B" or "3B", in
// order of increasing tightness. The default tolerance is "2B", which
// is the general standard for manufactured nuts.
// .
// The ISO tolerances are more complicated. For both screws and nuts the ISO tolerance has the form of a number
// and letter. The letter specifies the "fundamental deviation", also called the "tolerance position", the gap
// from the nominal size. The number specifies the allowed range (variability) of the thread heights. For
// screws, the letter must be "e", "f", "g", or "h", where "e" is the loosest and "h" means no gap. The number
// for a screw tolerance must be a value from 3-9 for crest diameter and one of 4, 6, or 8 for pitch diameter.
// A tolerance "6g" specifies both pitch and crest diameter to be the same, but they can be different, with a
// tolerance like "5g6g" specifies a pitch diameter tolerance of "5g" and a crest diameter tolerance of "6g".
// Smaller numbers give a tighter tolerance. The default ISO screw tolerance is "6g".
// .
// For ISO nuts the letters specifying the fundamental deviation are upper case and must be "G" or "H" where "G"
// is loose and "H" means no gap. The number specifying the variability must range from 4-8. An allowed (loose)
// nut tolerance is "7G". The default ISO tolerance is "6H".
// .
// Clearance holes have a different tolerance system, described in {{screw_hole()}}.
// .
// If you wish to create screws at the nominal size you can set the tolerance to 0 or "none".
// Subsection: screw_info and nut_info structures
// When you make a screw or nut, information about the object such as the thread characteristics
// head and drive size, or nut thickness are placed into a data structure. The screw and nut
// modules can accept screw names, as described above, or they can accept screw structures.
// When you use a screw structure as a specification, computed values like head type and size and
// driver characteristics are fixed and cannot be changed, but values that are not computed
// like length can still be altered. If you want to create an unusual part you can hand
// generate the structure with your desired parameters to fill in values that would normally
// be produced automatically from the standard tables. So if your hardware is missing from the
// tables, or is sized differently, you can still create the part. For details on the
// screw_info and nut_info structures, see {{screw_info()}} and {{nut_info()}}.
// .
// All of the screw related modules set the variable `$screw_spec` to contain the specification
// for their screw. This means that child modules can make use of this variable to create
// mating (or identical) parts.
/*
http://mdmetric.com/thddata.htm#idx
Seems to show JIS has same nominal thread as others
https://www.nbk1560.com/~/media/Images/en/Product%20Site/en_technical/11_ISO%20General%20Purpose%20Metric%20Screw%20Threads.ashx?la=en
Various ISO standards here: https://www.fasteners.eu/standards/ISO/4026/
Torx values: https://www.stanleyengineeredfastening.com/-/media/web/sef/resources/docs/other/socket_screw_tech_manual_1.ashx
*/
// Section: Making Screws
// Module: screw()
// Usage:
// screw([spec], [head], [drive], [thread=], [drive_size=], [length=|l=], [thread_len=], [undersize=], [shaft_undersize=], [head_undersize=], [tolerance=], [details=], [anchor=], [atype=], [orient=], [spin=]) [ATTACHMENTS];
// Description:
// Create a screw. See [screw and nut parameters](#section-screw-and-nut-parameters) for details on the parameters that define a screw.
// The tolerance determines the dimensions of the screw
// based on ISO and ASME standards. Screws fabricated at those dimensions will mate properly with standard hardware.
// Note that the $slop argument does not affect the size of screws: it only adjusts screw holes. This will work fine
// if you are printing both parts, but if you need to mate printed screws to metal parts you may need to adjust the size
// of the screws, which you can do with the undersize arguments.
// .
// You can generate a screw specification from {{screw_info()}}, possibly create a modified version using {{struct_set()}}, and pass that in rather than giving the parameters.
// .
// Various anchor types refer to different parts of the screw, some
// of which are labeled below. The "screw" anchor type (the
// default) is simply the entire screw, so TOP and BOTTOM refer to
// the head end and tip respectively, and CENTER is the midpoint of
// the whole screw, including the head. The "head" anchor refers to
// the head alone. Both of these anchor types refer to the bounding
// cylinder for the specified screw part, except for hex heads,
// which anchor to a hexagonal prism.
// Figure(2D,Med,VPD = 140, VPT = [18.4209, 14.9821, -3.59741], VPR = [0, 0, 0],NoAxes):
// rpos=33;
// fsize=2.5;
// projection(cut=true) xrot(-90)screw("M8", head="socket", length=25, thread_len=10);
// right(rpos)projection(cut=true) xrot(-90)screw("M8", head="flat", length=25, thread_len=10);
// color("black"){
// stroke([[5,0],[5,10]],endcaps="arrow2",width=.3);
// back(5)right(6)text("threads",size=fsize,anchor=LEFT);
// stroke([[5,10],[5,25]],endcaps="arrow2",width=.3);
// back(10+15/2)right(6)text("shank",size=fsize,anchor=LEFT);
// stroke([[-5,0],[-5,25]],endcaps="arrow2",width=.3);
// back(25/2)right(-6)text("shaft",size=fsize,anchor=RIGHT);
// }
// sh=10.2841;
// right(rpos)
// color("black"){
// stroke([[5,0],[5,10]],endcaps="arrow2",width=.3);
// back(5)right(6)text("threads",size=fsize,anchor=LEFT);
// stroke([[5,10],[5,10+sh]],endcaps="arrow2",width=.3);
// back(10+sh/2)right(6)text("shank",size=fsize,anchor=LEFT);
// stroke([[-5,0],[-5,10+sh]],endcaps="arrow2",width=.3);
// back((10+sh)/2)right(-6)text("shaft",size=fsize,anchor=RIGHT);
// }
// Arguments:
// spec = screw specification, e.g. "M5x1" or "#8-32". See [screw naming](#subsection-screw-naming). This can also be a screw specification structure of the form produced by {{screw_info()}}.
// head = head type. See [screw heads](#subsection-screw-heads) Default: none
// drive = drive type. See [screw heads](#subsection-screw-heads) Default: none
// ---
// length / l = length of screw (in mm)
// thread = thread type or specification. See [screw pitch](#subsection-standard-screw-pitch). Default: "coarse"
// drive_size = size of drive recess to override computed value
// thread_len = length of threaded portoin of screw (in mm), for making partly threaded screws. Default: fully threaded
// details = toggle some details in rendering. Default: true
// tolerance = screw tolerance. Determines actual screw thread geometry based on nominal sizing. See [tolerance](#subsection-tolerance). Default is "2A" for UTS and "6g" for ISO.
// undersize = amount to decrease screw diameter, a scalar to apply to all parts, or a 2-vector to control shaft and head. Default: 0
// undersize_shaft = amount to decrease diameter of the shaft of screw
// undersize_head = amount to decrease the head diameter of the screw
// atype = anchor type, one of "screw", "head", "shaft", "threads", "shank"
// anchor = Translate so anchor point on the shaft is at origin (0,0,0). See [anchor](attachments.scad#subsection-anchor). Default: `CENTER`
// spin = Rotate this many degrees around the Z axis after anchor. See [spin](attachments.scad#subsection-spin). Default: `0`
// orient = Vector to rotate top towards, after spin. See [orient](attachments.scad#subsection-orient). Default: `UP`
// Side Effects:
// `$screw_spec` is set to the spec specification structure.
// Anchor Types:
// screw = the entire screw (default)
// head = screw head (invalid for headless screws)
// shaft = screw shaft
// shank = unthreaded section of shaft (invalid if screw is fully threaded)
// threads = threaded section of screw
// Extra Anchors:
// top = top of screw
// bot = bottom of screw
// center = center of screw
// head_top = top of head (same as top for headless screws)
// head_bot = bottom of head (same as top for headless screws)
// head_center = center of head (same as top for headless screws)
// shaft_top = top of shaft
// shaft_bot = bottom of shaft
// shaft_center = center of shaft
// shank_top = top of shank (invalid if screw is fully threaded)
// shank_bot = bottom of shank (invalid if screw is fully threaded)
// shank_center = center of shank (invalid if screw is fully threaded)
// threads_top = top of threaded portion of screw (invalid if thread_len=0)
// threads_bot = bottom of threaded portion of screw (invalid if thread_len=0)
// threads_center = center of threaded portion of screw (invalid if thread_len=0)
// Example(Med): Selected UTS (English) screws
// $fn=32;
// xdistribute(spacing=8){
// screw("#6", length=12);
// screw("#6-32", head="button", drive="torx",length=12);
// screw("#6-32,3/4", head="hex");
// screw("#6", thread="fine", head="fillister",length=12, drive="phillips");
// screw("#6", head="flat small",length=12,drive="slot");
// screw("#6-32", head="flat large", length=12, drive="torx");
// screw("#6-32", head="flat undercut",length=12);
// screw("#6-24", head="socket",length=12); // Non-standard threading
// screw("#6-32", drive="hex", drive_size=1.5, length=12);
// }
// Example(Med): A few examples of ISO (metric) screws
// $fn=32;
// xdistribute(spacing=8){
// screw("M3", head="flat small",length=12);
// screw("M3", head="button",drive="torx",length=12);
// screw("M3", head="pan", drive="phillips",length=12);
// screw("M3x1", head="pan", drive="slot",length=12); // Non-standard threading!
// screw("M3", head="flat large",length=12);
// screw("M3", thread="none", head="flat", drive="hex",length=12); // No threads
// screw("M3", head="socket",length=12);
// screw("M5,18", head="hex");
// }
// Example(Med): Demonstration of all head types for UTS screws (using pitch zero for fast preview)
// xdistribute(spacing=15){
// ydistribute(spacing=15){
// screw("1/4", thread=0,length=8, anchor=TOP, head="none", drive="hex");
// screw("1/4", thread=0,length=8, anchor=TOP, head="none", drive="torx");
// screw("1/4", thread=0,length=8, anchor=TOP, head="none", drive="slot");
// screw("1/4", thread=0,length=8, anchor=TOP, head="none");
// }
// screw("1/4", thread=0, length=8, anchor=TOP, head="hex");
// ydistribute(spacing=15){
// screw("1/4", thread=0,length=8, anchor=TOP, head="socket", drive="hex");
// screw("1/4", thread=0,length=8, anchor=TOP, head="socket", drive="torx");
// screw("1/4", thread=0,length=8, anchor=TOP, head="socket");
// }
// ydistribute(spacing=15){
// screw("1/4", thread=0,length=8, anchor=TOP, head="socket ribbed", drive="hex",$fn=32);
// screw("1/4", thread=0,length=8, anchor=TOP, head="socket ribbed", drive="torx",$fn=32);
// screw("1/4", thread=0,length=8, anchor=TOP, head="socket ribbed",$fn=24);
// }
// ydistribute(spacing=15){
// screw("1/4", thread=0,length=8, anchor=TOP, head="button", drive="hex");
// screw("1/4", thread=0,length=8, anchor=TOP, head="button", drive="torx");
// screw("1/4", thread=0,length=8, anchor=TOP, head="button");
// }
// ydistribute(spacing=15){
// screw("1/4", thread=0,length=8, anchor=TOP, head="round", drive="slot");
// screw("1/4", thread=0,length=8, anchor=TOP, head="round", drive="phillips");
// screw("1/4", thread=0,length=8, anchor=TOP, head="round");
// }
// ydistribute(spacing=15){
// screw("1/4", thread=0,length=8, anchor=TOP, head="pan", drive="slot");
// screw("1/4", thread=0,length=8, anchor=TOP, head="pan", drive="phillips");
// screw("1/4", thread=0,length=8, anchor=TOP, head="pan");
// }
// ydistribute(spacing=15){
// screw("1/4", thread=0,length=8, anchor=TOP, head="fillister", drive="slot");
// screw("1/4", thread=0,length=8, anchor=TOP, head="fillister", drive="phillips");
// screw("1/4", thread=0,length=8, anchor=TOP, head="fillister");
// }
// ydistribute(spacing=15){
// screw("1/4", thread=0,length=8, anchor=TOP, head="flat", drive="slot");
// screw("1/4", thread=0,length=8, anchor=TOP, head="flat", drive="phillips");
// screw("1/4", thread=0,length=8, anchor=TOP, head="flat", drive="hex");
// screw("1/4", thread=0,length=8, anchor=TOP, head="flat", drive="torx");
// screw("1/4", thread=0,length=8, anchor=TOP, head="flat large");
// screw("1/4", thread=0,length=8, anchor=TOP, head="flat small");
// }
// ydistribute(spacing=15){
// screw("1/4", thread=0,length=8, anchor=TOP, head="flat undercut", drive="slot");
// screw("1/4", thread=0,length=8, anchor=TOP, head="flat undercut", drive="phillips");
// screw("1/4", thread=0,length=8, anchor=TOP, head="flat undercut");
// }
// ydistribute(spacing=15){
// screw("1/4", thread=0,length=8, anchor=TOP, head="flat 100", drive="slot");
// screw("1/4", thread=0,length=8, anchor=TOP, head="flat 100", drive="phillips");
// screw("1/4", thread=0,length=8, anchor=TOP, head="flat 100");
// }
// }
// Example(Med): Demonstration of all head types for metric screws without threading.
// xdistribute(spacing=15){
// ydistribute(spacing=15){
// screw("M6x0", length=8, anchor=TOP, head="none", drive="hex");
// screw("M6x0", length=8, anchor=TOP, head="none", drive="torx");
// screw("M6x0", length=8, anchor=TOP, head="none", drive="slot");
// screw("M6x0", length=8, anchor=TOP);
// }
// screw("M6x0", length=8, anchor=TOP, head="hex");
// ydistribute(spacing=15){
// screw("M6x0", length=8, anchor=TOP, head="socket", drive="hex");
// screw("M6x0", length=8, anchor=TOP, head="socket", drive="torx");
// screw("M6x0", length=8, anchor=TOP, head="socket");
// }
// ydistribute(spacing=15){
// screw("M6x0", length=8, anchor=TOP, head="socket ribbed", drive="hex", $fn=32);
// screw("M6x0", length=8, anchor=TOP, head="socket ribbed", drive="torx", $fn=32);
// screw("M6x0", length=8, anchor=TOP, head="socket ribbed", $fn=32);
// }
// ydistribute(spacing=15){
// screw("M6x0", length=8, anchor=TOP, head="pan", drive="slot");
// screw("M6x0", length=8, anchor=TOP, head="pan", drive="phillips");
// screw("M6x0", length=8, anchor=TOP, head="pan", drive="torx");
// screw("M6x0", length=8, anchor=TOP, head="pan");
// screw("M6x0", length=8, anchor=TOP, head="pan flat");
// }
// ydistribute(spacing=15){
// screw("M6x0", length=8, anchor=TOP, head="button", drive="hex");
// screw("M6x0", length=8, anchor=TOP, head="button", drive="torx");
// screw("M6x0", length=8, anchor=TOP, head="button");
// }
// ydistribute(spacing=15){
// screw("M6x0", length=8, anchor=TOP, head="cheese", drive="slot");
// screw("M6x0", length=8, anchor=TOP, head="cheese", drive="phillips");
// screw("M6x0", length=8, anchor=TOP, head="cheese", drive="torx");
// screw("M6x0", length=8, anchor=TOP, head="cheese");
// }
// ydistribute(spacing=15){
// screw("M6x0", length=8, anchor=TOP, head="flat", drive="phillips");
// screw("M6x0", length=8, anchor=TOP, head="flat", drive="slot");
// screw("M6x0", length=8, anchor=TOP, head="flat", drive="hex");
// screw("M6x0", length=8, anchor=TOP, head="flat", drive="torx");
// screw("M6x0", length=8, anchor=TOP, head="flat small");
// screw("M6x0", length=8, anchor=TOP, head="flat large");
// }
// }
// Example: The three different English (UTS) screw tolerances (labeled on their heads)
// module label(val)
// {
// difference(){
// children();
// yflip()linear_extrude(height=.35) text(val,valign="center",halign="center",size=8);
// }
// }
// $fn=64;
// xdistribute(spacing=15){
// label("1") screw("1/4-20,5/8", head="hex",orient=DOWN,atype="head", anchor=TOP,tolerance="1A"); // Loose
// label("2") screw("1/4-20,5/8", head="hex",orient=DOWN,atype="head", anchor=TOP,tolerance="2A"); // Standard
// label("3") screw("1/4-20,5/8", head="hex",orient=DOWN,atype="head", anchor=TOP,tolerance="3A"); // Tight
// }
// Example(2D): This example shows the gap between nut and bolt at the loosest tolerance for UTS. This gap is what enables the parts to mesh without binding and is part of the definition for standard metal hardware. Note that this gap is part of the standard definition for the metal hardware, not the 3D printing adjustment provided by the $slop parameter.
// $fn=32;
// projection(cut=true)xrot(-90){
// screw("1/4-20,1/4", head="hex",orient=UP,anchor=BOTTOM,tolerance="1A");
// down(INCH*1/20*2.145) nut("1/4-20", thickness=8, nutwidth=0.5*INCH, tolerance="1B");
// }
// Example: Here is a screw with nonstadard threading and a weird head size, which we create by modifying the screw structure:
// spec = screw_info("M6x2,12",head="socket");
// newspec = struct_set(spec,["head_size",20,"head_height",3]);
// screw(newspec);
// Example: A bizarre custom screw with nothing standard about it. If your screw is very strange, consider setting tolerance to zero so you get exactly the screw you defined. You'll need to create your own clearance between mating threads in this case.
// spec = [["system","ISO"],
// ["type","screw_info"],
// ["pitch", 2.3],
// ["head", "flat"],
// ["head_size", 20],
// ["head_size_sharp", 22],
// ["head_angle", 60],
// ["diameter",12],
// ["length",22]];
// screw(spec,tolerance=0);
function _get_spec(spec, needtype, origin, thread, // common parameters
head, drive, drive_size, // screw parameters
shape, thickness // nut parameters
) =
assert(needtype=="screw_info" || needtype=="nut_info")
assert(is_undef(thickness) || (is_num(thickness) && thickness>0) ||
in_list(_downcase_if_str(thickness),["thin","normal","thick","undersized","din"]),
"thickness must be a positive number of one of \"thin\", \"thick\", \"normal\", \"undersized\", or \"DIN\"")
assert(!(is_undef(spec) && is_undef($screw_spec)), "No screw spec given and no parent spec available to inherit")
let(spec=is_undef(spec) ? $screw_spec : spec)
assert(is_string(spec) || is_struct(spec), "Screw/nut specification must be a string or struct")
let(
specname = is_struct(spec) ? struct_val(spec,"name") : undef,
name = is_string(spec) ? spec
: struct_val(spec,"type") != needtype ? // if we switch between screw and nut we need a name
let(specname=struct_val(spec,"name"))
assert(is_string(specname),
"Parent screw_info or nut_info structure doesn't have a valid name, but a name is needed when child is of a different type")
specname
: undef,
p = is_struct(spec) ? struct_val(spec,"pitch") : undef,
thread = // If the origin of the struct is a hole with pitch zero and we are making a screw, try to find a nonzero pitch
is_undef(name) && struct_val(spec,"origin")=="screw_hole" && origin!="screw_hole" && p==0 && is_string(specname)
? let(temp_info = screw_info(specname,thread))
struct_val(temp_info,"pitch")
: thread
)
is_def(name) ? (needtype=="screw_info" ? screw_info(name,_origin=origin, thread= origin=="screw_hole" ? default(thread,true) : thread,
head=head, drive=drive, drive_size=drive_size)
: nut_info(name,_origin=origin, thread=thread, shape=shape, thickness=thickness))
:
assert(in_list(struct_val(spec,"type"), ["nut_info","screw_info"]), "Screw/nut spec is invalid struct type")
assert(is_undef(thread) || thread=="none" || thread==false || is_num(thread),
str("Thread type applied to struct specification must be numeric, \"none\" or false but got ",thread))
assert(is_undef(thickness) || is_num(thickness), str("thickness applied to struct specification must be numeric but is ",thickness))
assert(is_undef(head) || head=="none", str("The only head type allowed with struct specifications is \"none\" but got ",head))
assert(num_defined([drive,drive_size])==0, "You cannot change drive or drive_size when using a struct specification")
assert(is_undef(shape), "You cannot change nut shape when using a struct specification")
let(
spec = _struct_reset(spec,
[
if (origin=="screw") ["counterbore",0],
if (head=="none") ["head","none"],
if (head=="none") ["drive","none"],
if (thread==false || thread=="none") ["pitch",0]
else ["pitch",thread],
["thickness", thickness],
], grow=false)
)
origin==struct_val(spec, "origin") ? spec
: _struct_reset(spec, [
["thread_oversize",0],
["head_oversize",0]
], grow=false);
function _struct_reset(s, keyval, grow=true) =
let(
good = [for(kv=keyval) (grow || is_def(struct_val(s,kv[0]))) && is_def(kv[1])]
)
struct_set(s,flatten(bselect(keyval,good)));
function _nominal_diam(spec) = struct_val(spec,"diameter")+default(struct_val(spec,"threads_oversize"),0);
function screw(spec, head, drive, thread, drive_size,
length, l, thread_len, tolerance, details=true,
undersize, shaft_undersize, head_undersize,
atype="screw",anchor=BOTTOM, spin=0, orient=UP,
_shoulder_diam=0, _shoulder_len=0,
_internal=false, _counterbore, _teardrop) = no_function("screw");
module screw(spec, head, drive, thread, drive_size,
length, l, thread_len, tolerance, details=true,
undersize, shaft_undersize, head_undersize,
atype="screw",anchor, spin=0, orient=UP,
_shoulder_diam=0, _shoulder_len=0,
bevel,bevel1,bevel2,bevelsize,
_internal=false, _counterbore, _teardrop=false)
{
tempspec = _get_spec(spec, "screw_info", _internal ? "screw_hole" : "screw",
thread=thread, head=head, drive=drive, drive_size=drive_size);
undersize = is_num(undersize) ? [undersize,undersize]
: undersize;
dummyA=assert(is_undef(undersize) || is_vector(undersize,2), "Undersize must be a scalar or 2-vector")
assert(is_undef(undersize) || num_defined([shaft_undersize, head_undersize])==0,
"Cannot combine \"undersize\" with other more specific undersize parameters");
shaft_undersize = first_defined([shaft_undersize, undersize[0]]);
head_undersize = first_defined([head_undersize, undersize[1]]);
dummyB=assert(is_undef(shaft_undersize) || is_finite(shaft_undersize), "shaft_undersize must be a number")
assert(is_undef(head_undersize) || is_finite(head_undersize), "head_undersize must be a number")
assert(is_undef(_counterbore) || is_bool(_counterbore) || (is_finite(_counterbore) && _counterbore>=0),
"Counterbore must be a nonnegative number of boolean");
l = one_defined([l,length],"l,length",dflt=undef);
_counterbore = _counterbore==true ? struct_val(tempspec,"head_height")
: _counterbore==false ? undef
: _counterbore;
head = struct_val(tempspec,"head");
headless = head=="none";
flathead = starts_with(head,"flat");
reset_headsize = _internal && flathead ? struct_val(tempspec,"head_size_sharp") : undef;
spec=_struct_reset(tempspec,[
["length", l],
["threads_oversize", u_mul(-1,shaft_undersize)],
["head_oversize", u_mul(-1,head_undersize)],
["counterbore", _counterbore],
["thread_len", thread_len],
["head_size", reset_headsize],
]);
dummy = _validate_screw_spec(spec);
$screw_spec = spec;
pitch = struct_val(spec, "pitch") ;
threadspec = pitch==0 ? undef : thread_specification(spec, internal=_internal, tolerance=tolerance);
nominal_diam = _nominal_diam(spec);
d_major = pitch==0 ? nominal_diam : mean(struct_val(threadspec, "d_major"));
length = struct_val(spec,"length");
counterbore = default(struct_val(spec,"counterbore"),0);
user_thread_len = struct_val(spec,"thread_len");
dummyC = assert(in_list(atype,["shaft","head","shank","threads","screw","shoulder"]),str("Unknown anchor type: \"",atype,"\""))
assert(is_finite(length) && length>0, "Must specify positive screw length")
assert(is_finite(_shoulder_len) && _shoulder_len>=0, "Must specify a nonegative shoulder length")
assert(is_finite(_shoulder_diam) && _shoulder_diam>=0, "Must specify nonnegative shoulder diameter")
assert(is_undef(user_thread_len) || (is_finite(user_thread_len) && user_thread_len>=0), "Must specify nonnegative thread length")
assert(!_teardrop || pitch==0);
sides = max(pitch==0 ? 3 : 12, segs(nominal_diam/2));
head_height = headless || flathead ? 0
: counterbore==true || is_undef(counterbore) || counterbore==0 ? struct_val(spec, "head_height")
: counterbore;
head_diam = struct_val(spec, "head_size",0) + struct_val(spec, "head_oversize",0);
flat_height = !flathead ? 0
: let( given_height = struct_val(spec, "head_height"))
all_positive(given_height) ? given_height
: (struct_val(spec,"head_size_sharp")+struct_val(spec,"head_oversize",0)-d_major)/2/tan(struct_val(spec,"head_angle")/2);
flat_cbore_height = flathead && is_num(counterbore) ? counterbore : 0;
shoulder_adj = _shoulder_len>0 ? flat_height:0; // Adjustment because flathead height doesn't count toward shoulder length
shoulder_full = _shoulder_len==0 ? 0 : _shoulder_len + flat_height;
shank_len = is_def(user_thread_len) ? length - user_thread_len - (_shoulder_len==0?flat_height:0) : 0;
thread_len = is_def(user_thread_len) ? user_thread_len
: length - (_shoulder_len==0?flat_height:0);
dummyD = assert(!(atype=="shank" && shank_len==0), "Specified atype of \"shank\" but screw has no shank (thread_len not given or it equals shaft length)")
assert(!(atype=="shoulder" && _shoulder_len==0), "Specified atype of \"shoulder\" but screw has no shoulder")
assert(!(atype=="threads" && thread_len==0), "Specified atype of \"threads\" but screw has no threaded part (thread_len=0)")
assert(!(atype=="head" && headless), "You cannot anchor headless screws with atype=\"head\"");
eps_gen = 0.01;
eps_shoulder = headless && !_internal ? 0 : eps_gen;
eps_shank = headless && !_internal && _shoulder_len==0 ? 0 : eps_gen;
eps_thread = headless && !_internal && shank_len==0 && _shoulder_len==0 ? 0 : eps_gen;
dummyL = assert(_shoulder_len>0 || is_undef(flat_height) || flat_height < length,
str("Length of screw (",length,") is shorter than the flat head height (",flat_height,")"));
offset = atype=="head" ? (-head_height+flat_height-flat_cbore_height)/2
: atype=="shoulder" ? _shoulder_len/2 + flat_height
: atype=="shaft" ? _shoulder_len + (length+flat_height+shoulder_adj)/2
: atype=="shank" ? _shoulder_len + (length-thread_len+flat_height+shoulder_adj)/2
: atype=="threads" ? _shoulder_len + shoulder_adj + length-thread_len + thread_len/2
: atype=="screw" ? (length-head_height+_shoulder_len+shoulder_adj-flat_cbore_height)/2
: assert(false,"Unknown atype");
dummyM = //assert(!headless || !in_list(anchor,["head_top","head_bot","head_center"]), str("Anchor \"",anchor,"\" not allowed for headless screw"))
assert(shank_len>0 || !in_list(anchor,["shank_top","shank_bot","shank_center"]),
str("Screw has no unthreaded shank so anchor \"",anchor,"\" is not allowed"));
anchor_list = [
named_anchor("top", [0,0,offset+head_height+flat_cbore_height]),
named_anchor("bot", [0,0,-length-shoulder_full+offset]),
named_anchor("center", [0,0, -length/2 - shoulder_full/2 + head_height/2 + offset]),
named_anchor("head_top", [0,0,head_height+offset]),
named_anchor("head_bot", [0,0,-flat_height+offset]),
named_anchor("head_center", [0,0,(head_height-flat_height)/2+offset]),
if (_shoulder_len>0) named_anchor("shoulder_top", [0,0,offset-flat_height]),
if (_shoulder_len>0) named_anchor("shoulder_bot", [0,0,offset-shoulder_full]),
if (_shoulder_len>0) named_anchor("shoulder_center", [0,0,offset-flat_height-_shoulder_len/2]),
named_anchor("shaft_top", [0,0,-_shoulder_len-flat_height+offset]),
named_anchor("shaft_bot", [0,0,-length-shoulder_full+offset]),
named_anchor("shaft_center", [0,0,(-_shoulder_len-flat_height-length-shoulder_full)/2+offset]),
if (shank_len>0) named_anchor("shank_top", [0,0,-_shoulder_len-flat_height+offset]),
if (shank_len>0) named_anchor("shank_bot", [0,0,-shank_len-_shoulder_len-flat_height+offset]),
if (shank_len>0) named_anchor("shank_center", [0,0,-shank_len/2-_shoulder_len-flat_height+offset]),
named_anchor("threads_top", [0,0,-shank_len-_shoulder_len-flat_height+offset]),
named_anchor("threads_bot", [0,0,-length-shoulder_full+offset]),
named_anchor("threads_center", [0,0,(-shank_len-length-_shoulder_len-shoulder_full-flat_height)/2+offset])
];
rad_scale = _internal? (1/cos(180/sides)) : 1;
islop = _internal ? 4*get_slop() : 0;
vnf = head=="hex" && atype=="head" && counterbore==0 ? linear_sweep(hexagon(id=head_diam*rad_scale),height=head_height,center=true) : undef;
head_diam_full = head=="hex" ? 2*head_diam/sqrt(3) : head_diam;
attach_d = in_list(atype,["threads","shank","shaft"]) ? d_major
: atype=="screw" ? max(d_major,_shoulder_diam,default(head_diam_full,0))
: atype=="shoulder" ? _shoulder_diam
: is_def(vnf) ? undef
: head_diam_full;
attach_l = atype=="shaft" ? length-(_shoulder_len>0?0:flat_height)
: atype=="shoulder" ? _shoulder_len
: atype=="shank" ? shank_len
: atype=="threads" ? thread_len
: atype=="screw" ? length+head_height+shoulder_full + flat_cbore_height
: is_def(vnf) ? undef
: head_height+flat_height+flat_cbore_height;
bevelsize = default(bevelsize, d_major/12);
attachable(
vnf = vnf,
d = u_add(u_mul(attach_d, rad_scale), islop),
l = attach_l,
orient = orient,
anchor = anchor,
spin = spin,
anchors=anchor_list)
{
up(offset)
difference(){
union(){
screw_head(spec,details,counterbore=counterbore,flat_height=flat_height,
oversize=islop,teardrop=_teardrop);
if (_shoulder_len>0)
up(eps_shoulder-flat_height){
if (_teardrop)
teardrop(d=_shoulder_diam*rad_scale+islop, h=_shoulder_len+eps_shoulder, anchor=FRONT, orient=BACK, $fn=sides);
else
cyl(d=_shoulder_diam*rad_scale+islop, h=_shoulder_len+eps_shoulder, anchor=TOP, $fn=sides, chamfer1=details ? _shoulder_diam/30:0);
}
if (shank_len>0 || pitch==0){
L = pitch==0 ? length - (_shoulder_len==0?flat_height:0) : shank_len;
bevsize = (_internal ? -1 : 1)*bevelsize;
bev1 = details && pitch==0 && first_defined([bevel1,bevel,!_internal]) ? bevsize : 0;
bev2 = details && pitch==0 && first_defined([bevel2,bevel,headless && !_internal]) ? bevsize : 0;
down(_shoulder_len+flat_height-eps_shank)
if (_teardrop)
teardrop(d=d_major*rad_scale+islop, h=L+eps_shank, anchor=FRONT, orient=BACK, $fn=sides, chamfer1=bev1, chamfer2=bev2);
else
cyl(d=d_major*rad_scale+islop, h=L+eps_shank, anchor=TOP, $fn=sides, chamfer1=bev1, chamfer2=bev2);
}
if (thread_len>0 && pitch>0){
bev1 = details && first_defined([bevel1,bevel,!_internal]);
bev2 = details && first_defined([bevel2,bevel,!_internal && (flathead || _shoulder_len>0 || headless)]);
down(_shoulder_len+flat_height+shank_len-eps_thread)
threaded_rod([mean(struct_val(threadspec, "d_minor")),
mean(struct_val(threadspec, "d_pitch")),
d_major],
pitch = struct_val(threadspec, "pitch"),
l=thread_len+eps_thread, left_handed=false, internal=_internal,
bevel1=bev1,
bevel2=bev2,
$fn=sides, anchor=TOP);
}
}
if (!_internal) _driver(spec);
}
children();
}
}
// Module: screw_hole()
// Usage:
// screw_hole([spec], [head], [thread=], [length=|l=], [oversize=], [hole_oversize=], [teardrop=], [head_oversize], [tolerance=], [$slop=], [anchor=], [atype=], [orient=], [spin=]) [ATTACHMENTS];
// Description:
// Create a screw hole mask. See [screw and nut parameters](#section-screw-and-nut-parameters) for details on the parameters that define a screw.
// The screw hole can be threaded to receive a screw or it can be an unthreaded clearance hole.
// The tolerance determines the dimensions of the screw
// based on ISO and ASME standards. Screws fabricated at those dimensions will mate properly with standard hardware.
// The $slop argument makes the hole larger by 4*$slop to account for printing overextrusion. It defaults to 0.
// .
// You can generate a screw specification from {{screw_info()}}, possibly create a modified version, and pass that in rather than giving the parameters.
// .
// The tolerance should be a nut tolerance for a threaded hole or a clearance hole tolerance for clearance holes.
// For clearance holes, the UTS tolerances are "normal", "loose" and "close". ASME also specifies the same naming for metric clearance holes.
// However, ISO gives "fine", "medium" and "coarse" instead. This function accepts all of these in either system. It also takes "tight" to be equivalent to "close",
// even though no standard suggests it, because it's a natural opposite of "loose". The official tolerance designations for ISO are "H12" for "fine", "H13" for "medium"
// and "H14" for "coarse". These designations will also work, but only for metric holes. You can also set tolerance to 0 or "none" to produce holes at the nominal size.
// .
// If you want to produce holes for tapping you can use a tolerance of "tap". This produces a hole of the nominal screw diameter reduced by the thread pitch. You may still
// need to adjust $slop for best results. Some people screw machine screws directly into plastic without tapping. This works better with a somewhat larger hole, so
// a tolerance of "self tap" produces such a hole. Note that this tolerance also makes the default bevel2=true to bevel the top, which makes it much easier
// to start the screw. The "self tap" tolerance subtracts `0.72 * pitch` when pitch is below 1mm, `0.6 * pitch` when the pitch is over 1.5mm, and it interpolates between.
// It was tested in PLA with a Prusa MK3S and $slop=0.5 and worked on UTS screws from #2 up to 1/2 inch.
// .
// The counterbore parameter adds a cylindrical clearance hole above the screw shaft. For flat heads it extends above the flathead and for other screw types it
// replaces the head with a cylinder large enough in diameter for the head to fit. For a flat head you must specify the length of the counterbore. For other heads you can
// set counterbore to true and it will be sized to match the head height. The counterbore will extend 0.01 above the TOP of the hole mask to ensure no
// problems with differences. Note that the counterbore defaults to true for non-flathead screws. If you want the actual head shape to appear, set counterbore to zero.
// .
// For 3d printing circular holes can be problematic. One solution is to use octagonal holes, setting $fn=8. Another option is to use a teardrop hole, which
// can be accomplished by setting `teardrop=true`. The point of the teardrop will point in the Y direction (BACK) so you will need to ensure that you orient it
// correctly in your final model.
// .
// Anchoring for screw_hole() is the same as anchoring for {{screw()}}, with all the same anchor types and named anchors. If you specify a counterbore it is treated as
// the "head", or in the case of flat heads, it becomes part of the head. If you make a teardrop hole the point is ignored for purposes of anchoring.
// Arguments:
// spec = screw specification, e.g. "M5x1" or "#8-32". See [screw naming](#subsection-screw-naming). This can also be a screw specification structure of the form produced by {{screw_info()}}.
// head = head type. See [screw heads](#subsection-screw-heads) Default: none
// ---
// thread = thread type or specification for threaded masks, or false to make an unthreaded mask. See [screw pitch](#subsection-standard-screw-pitch). Default: false
// teardrop = if true produce teardrop hole. Only compatible with clearance holes, not threaded. Default: false
// oversize = amount to increase diameter of all screw parts, a scalar or length 3 vector. Default: 0
// oversize_hole = amount to increase diameter of the hole.
// oversize_head = amount to increase diameter of head.
// length / l= length of screw (in mm)
// counterbore = set to length of counterbore, or true to make a counterbore equal to head height. Default: false for flat heads and headless, true otherwise
// tolerance = threading or clearance hole tolerance. For internal threads, detrmines actual thread geometry based on nominal sizing. See [tolerance](#subsection-tolerance). Default is "2B" for UTS and 6H for ISO. For clearance holes, determines how much clearance to add. Default is "normal".
// bevel = if true create bevel at both ends of hole. Default: see below
// bevel1 = if true create bevel at bottom end of hole. Default: false
// bevel2 = if true create bevel at top end of hole. Default: true when tolerance="self tap", false otherwise
// $slop = add extra gap to account for printer overextrusion. Default: 0
// atype = anchor type, one of "screw", "head", "shaft", "threads", "shank"
// anchor = Translate so anchor point on the shaft is at origin (0,0,0). See [anchor](attachments.scad#subsection-anchor). Default: `CENTER`
// spin = Rotate this many degrees around the Z axis after anchor. See [spin](attachments.scad#subsection-spin). Default: `0`
// orient = Vector to rotate top towards, after spin. See [orient](attachments.scad#subsection-orient). Default: `UP`
// Side Effects:
// `$screw_spec` is set to the spec specification structure.
// Anchor Types:
// screw = the entire screw (default)
// head = screw head (invalid for headless screws)
// shaft = screw shaft
// shank = unthreaded section of shaft (invalid if screw is fully threaded)
// threads = threaded section of screw
// Extra Anchors:
// top = top of screw
// bot = bottom of screw
// center = center of screw
// head_top = top of head (invalid for headless screws)
// head_bot = bottom of head (invalid for headless screws)
// head_center = center of head (invalid for headless screws)
// shaft_top = top of shaft
// shaft_bot = bottom of shaft
// shaft_center = center of shaft
// shank_top = top of shank (invalid if screw is fully threaded)
// shank_bot = bottom of shank (invalid if screw is fully threaded)
// shank_center = center of shank (invalid if screw is fully threaded)
// threads_top = top of threaded portion of screw (invalid if thread_len=0)
// threads_bot = bottom of threaded portion of screw (invalid if thread_len=0)
// threads_center = center of threaded portion of screw (invalid if thread_len=0)
// Example: Counterbored clearance hole
// diff()
// cuboid(20)
// attach(TOP)
// screw_hole("1/4-20,.5",head="socket",counterbore=5,anchor=TOP);
// Example: Clearance hole for flathead
// diff()
// cuboid(20)
// attach(TOP)
// screw_hole("1/4-20,.5",head="flat",counterbore=0,anchor=TOP);
// Example: Threaded hole
// diff()
// cuboid(20)
// attach(FRONT)
// screw_hole("M16,15",anchor=TOP,thread=true);
module screw_hole(spec, head, thread, oversize, hole_oversize, head_oversize,
length, l, thread_len, tolerance=undef, counterbore, teardrop=false,
bevel, bevel1, bevel2,
atype="screw",anchor=CENTER,spin=0, orient=UP)
{
screwspec = _get_spec(spec, "screw_info", "screw_hole",
thread=thread, head=head);
bevel1 = first_defined([bevel1,bevel,false]);
bevel2 = first_defined([bevel2,bevel,tolerance=="self tap"]);
thread = default(thread,false);
checkhead = struct_val(screwspec,"head");
default_counterbore = checkhead=="none" || starts_with(checkhead,"flat") ? 0 : true;
counterbore = default(counterbore, default_counterbore);
dummy = _validate_screw_spec(screwspec);
threaded = thread==true || (is_finite(thread) && thread>0) || (is_undef(thread) && struct_val(screwspec,"pitch")>0);
dummy2 = assert(!threaded || !teardrop, "Cannot make threaded teardrop holes");
if (threaded || is_def(oversize) || is_def(hole_oversize) || tolerance==0 || tolerance=="none") {
undersize = is_def(oversize) ? -oversize
: -[default(hole_oversize,0), default(head_oversize,0)];
default_tag("remove")
screw(spec,head=head,thread=thread,undersize=undersize,
length=length,l=l,thread_len=thread_len, tolerance=tolerance, _counterbore=counterbore,
bevel=bevel, bevel1=bevel1, bevel2=bevel2,
atype=atype, anchor=anchor, spin=spin, orient=orient, _internal=true, _teardrop=teardrop)
children();
}
else {
tolerance = default(tolerance, "normal");
pitch = struct_val(screwspec,"pitch");
dummy3 = assert((downcase(tolerance) != "tap" && downcase(tolerance)!="self tap") || pitch!=0,
"\"tap\" clearance requires a pitch size, but pitch is set to zero");
// UTS clearances from ASME B18.2.8
UTS_clearance = [
[ // Close fit
[0.1120 * INCH,0.008*INCH],
[0.1250 * INCH, 1/64*INCH],
[7/16 * INCH, 1/64*INCH],
[1/2 * INCH, 1/32*INCH],
[1.25 * INCH, 1/32*INCH],
[1.375 * INCH, 1/16*INCH]
],
[ // Normal fit
[0.1120 * INCH, 1/64*INCH],
[0.1250 * INCH, 1/32*INCH],
[7/16 * INCH, 1/32*INCH],
[1/2 * INCH, 1/16*INCH],
[7/8 * INCH, 1/16*INCH],
[1 * INCH, 3/32*INCH],
[1.25 * INCH, 3/32*INCH],
[1.375 * INCH, 1/8*INCH],
],
[ // Loose fit
[0.1120 * INCH, 1/32*INCH],
[0.1250 * INCH, 3/64*INCH],
[7/16 * INCH, 3/64*INCH],
[1/2 * INCH, 7/64*INCH],
[5/8 * INCH, 7/64*INCH],
[3/4 * INCH, 5/32*INCH],
[1 * INCH, 5/32*INCH],
[1.125 * INCH, 3/16*INCH],
[1.25 * INCH, 3/16*INCH],
[1.375 * INCH,15/64*INCH]
]
];
// ISO clearances appear in ASME B18.2.8 and ISO 273
ISO_clearance = [
[ // Close, Fine, H12
[2.5, 0.1],
[3.5, 0.2],
[4, 0.3],
[5, 0.3],
[6, 0.4],
[8, 0.4],
[10, 0.5],
[12, 1],
[42, 1],
[48, 2],
[80, 2],
[90, 3],
[100, 4],
],
[ // Normal, Medium, H13
[1.6, 0.2],
[2, 0.4],
[3.5, 0.4],
[4, 0.5],
[5, 0.5],
[6, 0.6],
[8, 1],
[10, 1],
[12, 1.5],
[16, 1.5],
[20, 2],
[24, 2],
[30, 3],
[42, 3],
[48, 4],
[56, 6],
[90, 6],
[100, 7],
],
[ // Loose, Coarse, H14
[1.6, 0.25],
[2, 0.3],
[3, 0.6],
[3.5, 0.7],
[4, 0.8],
[5, 0.8],
[6, 1],
[8, 2],
[10, 2],
[12, 2.5],
[16, 2.5],
[20, 4],
[24, 4],
[30, 5],
[36, 6],
[42, 6],
[48, 8],
[56, 10],
[72, 10],
[80, 11],
[90, 11],
[100,12],
]
];
tol_ind = in_list(downcase(tolerance), ["close", "fine", "tight"]) ? 0
: in_list(downcase(tolerance), ["normal", "medium", "tap", "self tap"]) ? 1
: in_list(downcase(tolerance), ["loose", "coarse"]) ? 2
: in_list(tolerance, ["H12","H13","H14"]) ?
assert(struct_val(screwspec,"system")=="ISO", str("Hole tolerance ", tolerance, " only allowed with ISO screws"))
parse_int(substr(tolerance,1))
: assert(false,str("Unknown tolerance ",tolerance, " for clearance hole"));
tol_table = struct_val(screwspec,"system")=="UTS" ? UTS_clearance[tol_ind] : ISO_clearance[tol_ind];
// If we got here, hole_oversize is undefined and oversize is undefined
hole_oversize = downcase(tolerance)=="tap" ? -pitch
: downcase(tolerance)=="self tap" ? -pitch*lookup(pitch,[[1,0.72],[1.5,.6]])
: lookup(_nominal_diam(screwspec), tol_table);
head_oversize = first_defined([head_oversize,hole_oversize]);
default_tag("remove")
screw(spec,head=head,thread=0,shaft_undersize=-hole_oversize, head_undersize=-head_oversize,
length=length,l=l,thread_len=thread_len, _counterbore=counterbore,
bevel=bevel, bevel1=bevel1, bevel2=bevel2, bevelsize=pitch>0?pitch:undef,
atype=atype, anchor=anchor, spin=spin, orient=orient, _internal=true, _teardrop=teardrop)
children();
}
}
// Module: shoulder_screw()
// Usage:
// shoulder_screw(s, d, length, [head=], [thread_len=], [tolerance=], [head_size=], [drive=], [drive_size=], [thread=], [undersize=], [shaft_undersize=], [head_undersize=], [shoulder_undersize=],[atype=],[anchor=],[orient=],[spin=]) [ATTACHMENTS];
// Description:
// Create a shoulder screw. See [screw and nut parameters](#section-screw-and-nut-parameters) for details on the parameters that define a screw.
// The tolerance determines the dimensions of the screw
// based on ISO and ASME standards. Screws fabricated at those dimensions will mate properly with standard hardware.
// Note that the $slop argument does not affect the size of screws: it only adjusts screw holes. This will work fine
// if you are printing both parts, but if you need to mate printed screws to metal parts you may need to adjust the size
// of the screws, which you can do with the undersize arguments.
// .
// Unlike a regular screw, a shoulder screw is based on its shoulder dimensions: diameter and length. The ISO and ASME standards
// specify for a given shoulder diameter the thread size and even the length of the threads. Note that these standards specify only
// a small range of sizes. You can specify a shoulder screw by giving the system, either "ISO" or "UTS" and the shoulder diameter
// and length, and shoulder_screw() will supply the other parameters.
// .
// Hardware sources like McMaster sell many screws that don't comply with the standards. If you want to make such a screw then
// you can specify parameters like thread_len, the length of the threaded portion below the shoulder, and you can choose a different head
// type. You will need to specify the size of the head, since it cannot be looked up in tables. You can also
// generate a screw specification from {{screw_info()}}, possibly create a modified version using {{struct_set()}}, and pass that in rather than giving the parameters.
// .
// The anchors and anchor types are the same as for {{screw()}} except that there is an anchor type for the shoulder and an additional set of named anchors
// refering to parts of the shoulder.
// Arguments:
// s = screw system to use, case insensitive, either "ISO", "UTS", "english" or "metric", or a screw name or specification. See [screw naming](#subsection-screw-naming).
// d = nominal shoulder diameter in mm for ISO or inches for UTS
// length = length of the shoulder (in mm)
// ---
// thread_len = length of threads
// tolerance = screw tolerance. Determines actual screw thread geometry based on nominal sizing. See [tolerance](#subsection-tolerance). Default is "2A" for UTS and "6g" for ISO.
// drive = drive type. See [screw heads](#subsection-screw-heads) set to "none" for no drive. Default: "hex"
// drive_size = size of the drive recess
// thread = thread type or specification. See [screw pitch](#subsection-standard-screw-pitch). Default: "coarse"
// spec = screw specification to define the thread size
// head_size = scalar or vector to give width or [width, height]. If you only give width, height is computed using a formula for socket heads. For flat head screws the second value in the vector is the sharp size; if you don't give it then the sharp size will be 12% more than the given size
// Side Effects:
// `$screw_spec` is set to the spec specification structure.
// Anchor Types:
// screw = the entire screw (default)
// head = screw head (invalid for headless screws)
// shoulder = the shoulder
// shaft = screw shaft
// threads = threaded section of screw
// Extra Anchors:
// top = top of screw
// bot = bottom of screw
// center = center of screw
// head_top = top of head (invalid for headless screws)
// head_bot = bottom of head (invalid for headless screws)
// head_center = center of head (invalid for headless screws)
// shoulder_top = top of shoulder
// shoulder_bot = bottom of shoulder
// shoulder_center = center of shoulder
// shaft_top = top of shaft
// shaft_bot = bottom of shaft
// shaft_center = center of shaft
// threads_top = top of threaded portion of screw (invalid if thread_len=0)
// threads_bot = bottom of threaded portion of screw (invalid if thread_len=0)
// threads_center = center of threaded portion of screw (invalid if thread_len=0)
// Example: ISO shoulder screw
// shoulder_screw("iso",10,length=20);
// Example: English shoulder screw
// shoulder_screw("english",1/2,length=20);
// Example: Custom example. You must specify thread_len and head_size when creating custom configurations.
// shoulder_screw("M6", 9.3, length=17, thread_len=8, head_size=14);
// Example: Another custom example:
// shoulder_screw("M6", 9.3, length=17, thread_len=8, head_size=14, head="button", drive="torx");
// Example: Threadless
// shoulder_screw("iso",10,length=15,thread=0);