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Fix anchors for rack and spur gear and tweak docs

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This commit is contained in:
Adrian Mariano 2023-08-27 10:00:40 -04:00
parent 98816d07f9
commit 5197c013b8
2 changed files with 192 additions and 109 deletions
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20
attachments.scad
View File

@ -2827,13 +2827,15 @@ function attach_geom(
assert(is_bool(two_d))
assert(is_vector(axis))
!is_undef(size)? (
let(
over_f = is_undef(override) ? function(anchor) [undef,undef,undef]
: is_func(override) ? override
: function(anchor) _local_struct_val(override,anchor)
)
two_d? (
let(
size2 = default(size2, size.x),
shift = default(shift, 0),
over_f = is_undef(override) ? function(anchor) [undef,undef]
: is_func(override) ? override
: function(anchor) _local_struct_val(override,anchor)
shift = default(shift, 0)
)
assert(is_vector(size,2))
assert(is_num(size2))
@ -2847,7 +2849,7 @@ function attach_geom(
assert(is_vector(size,3))
assert(is_vector(size2,2))
assert(is_vector(shift,2))
["prismoid", size, size2, shift, axis, cp, offset, anchors]
["prismoid", size, size2, shift, axis, over_f, cp, offset, anchors]
)
) : !is_undef(vnf)? (
assert(is_vnf(vnf))
@ -3250,6 +3252,7 @@ function _find_anchor(anchor, geom) =
let(
size=geom[1], size2=geom[2],
shift=point2d(geom[3]), axis=point3d(geom[4]),
override = geom[5](anchor),
anch = rot(from=axis, to=UP, p=anchor),
offset = rot(from=axis, to=UP, p=offset),
h = size.z,
@ -3276,9 +3279,9 @@ function _find_anchor(anchor, geom) =
v3 = unit(line[1]-line[0],UP) * anch.z
)
unit(v3,UP),
vec = rot(from=UP, to=axis, p=vec2),
pos2 = rot(from=UP, to=axis, p=pos)
) [anchor, pos2, vec, oang]
vec = default(override[1],rot(from=UP, to=axis, p=vec2)),
pos2 = default(override[0],rot(from=UP, to=axis, p=pos))
) [anchor, pos2, vec, default(override[2],oang)]
) : type == "conoid"? ( //r1, r2, l, shift
assert(anchor.z == sign(anchor.z), "The Z component of an anchor for a cylinder/cone must be -1, 0, or 1")
let(
@ -3388,6 +3391,7 @@ function _find_anchor(anchor, geom) =
frpt = [size.x/2*anchor.x, -size.y/2],
bkpt = [size2/2*anchor.x+shift, size.y/2],
override = geom[4](anchor),
f=echo(o=override),
pos = default(override[0],point2d(cp) + lerp(frpt, bkpt, u) + point2d(offset)),
svec = point3d(line_normal(bkpt,frpt)*anchor.x),
vec = is_def(override[1]) ? override[1]

277
gears.scad
View File

@ -114,7 +114,7 @@ function _inherit_gear_thickness(thickness) =
// from the start of one tooth to the start of the text tooth. The circular pitch can be computed as
// `PI*d/teeth` where `d` is the diameter of the pitch circle and `teeth` is the number of teeth on the gear.
// This simply divides up the pitch circle into the specified number of teeth. However, the customary
// way to specify metric gears is using the module, the number of teeth that would fit on the diameter of the gear: `m=d/teeth`.
// way to specify metric gears is using the module, ratio of the diameter of the gear to the number of teeth: `m=d/teeth`.
// The module is hence the circular pitch divided by a factor of π. A third way to specify gear sizes is the diametral pitch,
// which is the number of teeth that fit on a gear with a diameter of one inch, or π times the number of teeth per inch.
// Note that for the module or circular pitch, larger values make larger teeth,
@ -486,15 +486,16 @@ function _inherit_gear_thickness(thickness) =
// Topics: Gears, Parts
// See Also: rack(), spur_gear(), spur_gear2d(), bevel_gear()
// Usage: As a Module
// spur_gear(circ_pitch, teeth, thickness, [shaft_diam], [hide=], [pressure_angle=], [clearance=], [backlash=], [helical=], [slices=], [internal=], [herringbone=]) [ATTACHMENTS];
// spur_gear(mod=, teeth=, thickness=, [shaft_diam=], ...) [ATTACHMENTS];
// spur_gear(circ_pitch, teeth, [thickness], [helical=], [pressure_angle=], [profile_shift=], [backlash=], [shaft_diam=], [hide=], [clearance=], [slices=], [internal=], [herringbone=]) [ATTACHMENTS];
// spur_gear(mod=|diam_pitch=, teeth=, [thickness=], ...) [ATTACHMENTS];
// Usage: As a Function
// vnf = spur_gear(circ_pitch, teeth, thickness, [shaft_diam=], ...);
// vnf = spur_gear(mod=, teeth=, thickness=, [shaft_diam=], ...);
// vnf = spur_gear(circ_pitch, teeth, [thickness], ...);
// vnf = spur_gear(mod=|diam_pitch=, teeth=, [thickness=], ...);
// Description:
// Creates a involute spur gear, helical gear, or a mask for an internal ring gear. The module `spur_gear()` gives an involute
// spur gear, with reasonable defaults for all the parameters. Normally, you should just choose the
// first 4 parameters, and let the rest be default values. Spur gears have straight teeth and
// Creates a involute spur gear, helical gear, herringbone gear, or a mask for an internal ring gear.
// For more information about gears, see [A Quick Introduction to Gears](gears.scad#section-a-quick-introduction-to-gears).
// You must specify the teeth size using either `mod=`, `circ_pitch=` or `diam_pitch=`, and you
// must give the number of teeth of the gear. Spur gears have straight teeth and
// mesh together on parallel shafts without creating any axial thrust. The teeth engage suddenly across their
// entire width, creating stress and noise. Helical gears have angled teeth and engage more gradually, so they
// run more smoothly and quietly, however they do produce thrust along the gear axis. This can be
@ -502,49 +503,63 @@ function _inherit_gear_thickness(thickness) =
// Helical gears can mesh along shafts that are not parallel, where the angle between the shafts is
// the sum of the helical angles of the two gears.
// .
// The module `spur_gear()` gives a gear in
// the XY plane, centered on the origin, with one tooth centered on the positive Y axis. The most
// important function is `gear_dist()`, which tells how far apart to space gears that are meshing, and
// `outer_radius()`, which gives the size of the region filled by the gear. A gear has a "pitch
// circle", which is an invisible circle that cuts through the middle of each tooth (though not the
// exact center). In order for two gears to mesh, their pitch circles should just touch. So the
// distance between their centers should be `mesh_radius()` for one, plus `mesh_radius()` for the
// other, which gives the overall meshing distance. In order for two gears to mesh, they must
// have the same `pitch` and `pressure_angle` parameters. `pitch` gives the number of millimeters
// of arc around the pitch circle covered by one tooth and one space between teeth. The
// `pressure_angle` controls how flat or bulged the sides of the teeth are. Common values include
// 14.5 degrees and 20 degrees, and occasionally 25. The default here is 20 degrees.
// The ratio of `teeth` for two meshing gears gives how many times one will make a full revolution
// when the the other makes one full revolution. If the two numbers are coprime (i.e. are not both
// divisible by the same number greater than 1), then every tooth on one gear will meet every tooth
// on the other, for more even wear. So coprime numbers of teeth are good.
// Normally, If the number of teeth is too few, gear tooth shapes may be undercut to allow meshing
// with other gears. If this is the case, profile shifting will automatically be applies to enlarge
// the teeth, removing the undercut. This may add to the distance needed between gears.
// If you with to override this correction, you can use `profile_shift=0`, or set it to a specific
// value like 0.5.
// The module creates the gear in the XY plane, centered on the origin, with one tooth centered on the positive Y axis.
// In order for two gears to mesh they must have the same tooth size and `pressure_angle`, and
// generally the helical angles should be of opposite sign.
// The usual pressure angle (and default) is 20 degrees. Another common value is 14.5 degrees.
// Ideally the teeth count of two meshing gears will be relatively prime because this ensures that
// every tooth on one gear will meet every tooth on the other, creating even wear.
// .
// The "pitch circle" of the gear is a reference circle where the circular pitch is defined that
// is used to construct the gear. It runs approximately through the centers of the teeth.
// Two basic gears will mesh when their pitch circles are tangent. Anchoring for these gears is
// done on the pitch circle by default, so basic gears can be meshed using anchoring.
// However, when a gear has a small number of teeth, the basic gear form will result in undercutting,
// which weakens the teeth. To avoid this, profile shifting is automatically applied and in this
// case, the distance between the gears is a complicated calculation and must be determined using {{gear_dist()}}.
// If you wish to override this correction, you can use `profile_shift=0`, or set it to a specific
// value like 0.5. Another complication with profile shifted gears is that the tips may be too long,
// which can eat into the clearance space. To address this problem you can use the `shorten` parameter,
// which you can compute using {{gear_shorten()}}.
// .
// Helical gears can mesh with skew or crossed axes, a configuration sometimes called "screw gears".
// Without profile shifting, that angle is the sum of the helical angles.
// With profile shifting it is slightly different and is given by {{gear_skew_angle()}}.
// These gears still mesh on the pitch circle when they are not profile shifted, but the correction to
// gear separation for a proper mesh of profile shifted gears is different for skew gears and is
// computed using {{gear_dist_skew()}}.
// .
// To create space for gears to mesh in practice you will need to set a positive value for backlash, or
// use the `backlash` argument to {{gear_dist()}}.
// Arguments:
// circ_pitch = The circular pitch, or distance in mm between teeth around the pitch circle.
// circ_pitch = The circular pitch, or distance between teeth around the pitch circle.
// teeth = Total number of teeth around the entire perimeter
// thickness = Thickness of gear in mm
// shaft_diam = Diameter of the hole in the center, in mm. Default: 0 (no shaft hole)
// thickness = Thickness of gear. Default: 10
// ---
// hide = Number of teeth to delete to make this only a fraction of a circle
// pressure_angle = Controls how straight or bulged the tooth sides are. In degrees.
// clearance = Clearance gap at the bottom of the inter-tooth valleys.
// backlash = Gap between two meshing teeth, in the direction along the circumference of the pitch circle
// helical = Teeth are slanted around the spur gear at this angle away from the gear axis of rotation.
// slices = Number of vertical layers to divide gear into. Useful for refining gears with `helical`.
// mod = The module of the gear (pitch diameter / teeth)
// diam_pitch = The diametral pitch, or number of teeth per inch of pitch diameter. Note that the diametral pitch is a completely different thing than the pitch diameter.
// mod = The metric module/modulus of the gear, or mm of pitch diameter per tooth.
// internal = If true, create a mask for difference()ing from something else.
// helical = Teeth spiral around the gear at this angle, positive for left handed, negative for right handed. Default: 0
// herringbone = If true, and helical is set, creates a herringbone gear. Default: False
// pressure_angle = Controls how straight or bulged the tooth sides are. In degrees. Default: 20
// profile_shift = Profile shift factor x. Default: "auto"
// herringbone = If true, and helical is set, creates a herringbone gear.
// shorten = Shorten gear tips by the module times this value. Needed for large profile shifted gears. Default: 0
// backlash = Gap between two meshing teeth, in the direction along the circumference of the pitch circle. Default: 0
// shaft_diam = Diameter of the hole in the center. Default: 0 (no shaft hole)
// hide = Number of teeth to delete to make this only a fraction of a circle. Default: 0
// gear_spin = Rotate gear and children around the gear center, regardless of how gear is anchored. Default: 0
// clearance = Clearance gap at the bottom of the inter-tooth valleys. Default: mod/4
// slices = Number of vertical layers to divide gear into. Useful for refining gears with `helical`.
// internal = If true, create a mask for difference()ing from something else.
// atype = Set to "root", "tip" or "pitch" to determine anchoring circle. Default: "pitch"
// anchor = Translate so anchor point 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:
// If internal is true then the default tag is "remove"
// Anchor Types:
// root = anchor on the root circle
// pitch = anchor on the pitch circle (default)
// tip = anchor on the tip circle
// Example: Spur Gear
// spur_gear(circ_pitch=5, teeth=20, thickness=8, shaft_diam=5);
// Example: Metric Gear
@ -681,6 +696,7 @@ function spur_gear(
mod,
pitch,
gear_spin = 0,
atype = "pitch",
anchor = CENTER,
spin = 0,
orient = UP
@ -707,6 +723,12 @@ function spur_gear(
assert(is_finite(gear_spin))
let(
pr = pitch_radius(circ_pitch, teeth, helical),
or = outer_radius(circ_pitch, teeth, helical=helical, profile_shift=profile_shift, internal=internal,shorten=shorten),
rr = _root_radius(circ_pitch, teeth, clearance, profile_shift=profile_shift, internal=internal),
anchor_rad = atype=="pitch" ? pr
: atype=="tip" ? or
: atype=="root" ? rr
: assert(false,"atype must be one of \"root\", \"tip\" or \"pitch\""),
circum = 2 * PI * pr,
twist = 360*thickness*tan(helical)/circum,
slices = default(slices, ceil(twist/360*segs(pr)+1)),
@ -734,7 +756,7 @@ function spur_gear(
cap_vnf, zflip(p=cap_vnf),
]),
vnf = zrot(gear_spin, p=rvnf)
) reorient(anchor,spin,orient, h=thickness, r=pr, p=vnf);
) reorient(anchor,spin,orient, h=thickness, r=anchor_rad, p=vnf);
module spur_gear(
@ -757,6 +779,7 @@ module spur_gear(
diam_pitch,
mod,
gear_spin = 0,
atype="pitch",
anchor = CENTER,
spin = 0,
orient = UP
@ -781,11 +804,17 @@ module spur_gear(
assert(slices==undef || (is_integer(slices) && slices>0))
assert(is_finite(gear_spin));
pr = pitch_radius(circ_pitch, teeth, helical);
or = outer_radius(circ_pitch, teeth, helical=helical, profile_shift=profile_shift, internal=internal,shorten=shorten);
rr = _root_radius(circ_pitch, teeth, clearance, profile_shift=profile_shift, internal=internal);
anchor_rad = atype=="pitch" ? pr
: atype=="tip" ? or
: atype=="root" ? rr
: assert(false,"atype must be one of \"root\", \"tip\" or \"pitch\"");
circum = 2 * PI * pr;
twist = 360*thickness*tan(helical)/circum;
slices = default(slices, ceil(twist/360*segs(pr)+1));
default_tag("remove", internal) {
attachable(anchor,spin,orient, r=pr, l=thickness) {
attachable(anchor,spin,orient, r=anchor_rad, l=thickness) {
zrot(gear_spin)
if (herringbone) {
zflip_copy() down(0.01)
@ -849,34 +878,62 @@ module spur_gear(
// Topics: Gears, Parts
// See Also: rack(), spur_gear(), spur_gear2d(), bevel_gear()
// Usage: As Module
// spur_gear2d(circ_pitch, teeth, [hide=], [pressure_angle=], [clearance=], [backlash=], [internal=]) [ATTACHMENTS];
// spur_gear2d(mod=, teeth=, [hide=], [pressure_angle=], [clearance=], [backlash=], [internal=]) [ATTACHMENTS];
// spur_gear2d(circ_pitch, teeth, [pressure_angle=], [profile_shift=], [shorten=], [hide=], [shaft_diam=], [clearance=], [backlash=], [internal=]) [ATTACHMENTS];
// spur_gear2d(mod=|diam_pitch=, teeth=, [pressure_angle=], [profile_shift=], [shorten=], [hide=], [shaft_diam=], [clearance=], [backlash=], [internal=]) [ATTACHMENTS];
// Usage: As Function
// rgn = spur_gear2d(circ_pitch, teeth, [hide=], [pressure_angle=], [clearance=], [backlash=], [internal=]);
// rgn = spur_gear2d(mod=, teeth=, [hide=], [pressure_angle=], [clearance=], [backlash=], [internal=]);
// rgn = spur_gear2d(circ_pitch, teeth, [pressure_angle=], [profile_shift=], [shorten=], [hide=], [shaft_diam=], [clearance=], [backlash=], [internal=]);
// rgn = spur_gear2d(mod=, teeth=, [pressure_angle=], [profile_shift=], [shorten=], [hide=], [shaft_diam=], [clearance=], [backlash=], [internal=]);
// Description:
// When called as a module, creates a 2D involute spur gear. When called as a function,
// returns a 2D region for the 2D involute spur gear. Normally, you should just specify the
// first 2 parameters `circ_pitch` and `teeth`, and let the rest be default values.
// Meshing gears must match in `circ_pitch`, `pressure_angle`, and `helical`, and be separated by
// the distance given by {{gear_dist()}}.
// Creates a 2D involute spur gear, or a mask for an internal ring gear.
// For more information about gears, see [A Quick Introduction to Gears](gears.scad#section-a-quick-introduction-to-gears).
// You must specify the teeth size using either `mod=`, `circ_pitch=` or `diam_pitch=`, and you
// must give the number of teeth.
// .
// The module creates the gear in centered on the origin, with one tooth centered on the positive Y axis.
// In order for two gears to mesh they must have the same tooth size and `pressure_angle`
// The usual pressure angle (and default) is 20 degrees. Another common value is 14.5 degrees.
// Ideally the teeth count of two meshing gears will be relatively prime because this ensures that
// every tooth on one gear will meet every tooth on the other, creating even wear.
// .
// The "pitch circle" of the gear is a reference circle where the circular pitch is defined that
// is used to construct the gear. It runs approximately through the centers of the teeth.
// Two basic gears will mesh when their pitch circles are tangent. Anchoring for these gears is
// done on the pitch circle by default, so basic gears can be meshed using anchoring.
// However, when a gear has a small number of teeth, the basic gear form will result in undercutting,
// which weakens the teeth. To avoid this, profile shifting is automatically applied and in this
// case, the distance between the gears is a complicated calculation and must be determined using {{gear_dist()}}.
// If you wish to override this correction, you can use `profile_shift=0`, or set it to a specific
// value like 0.5. Another complication with profile shifted gears is that the tips may be too long,
// which can eat into the clearance space. To address this problem you can use the `shorten` parameter,
// which you can compute using {{gear_shorten()}}.
// .
// To create space for gears to mesh in practice you will need to set a positive value for backlash, or
// use the `backlash` argument to {{gear_dist()}}.
// Arguments:
// circ_pitch = The circular pitch, or distance between teeth around the pitch circle, in mm.
// teeth = Total number of teeth around the spur gear.
// hide = Number of teeth to delete to make this only a fraction of a circle
// pressure_angle = Controls how straight or bulged the tooth sides are. In degrees.
// ---
// hide = Number of teeth to delete to make this only a fraction of a circle
// clearance = Gap between top of a tooth on one gear and bottom of valley on a meshing gear (in millimeters)
// backlash = Gap between two meshing teeth, in the direction along the circumference of the pitch circle
// helical = The angle of the rack teeth away from perpendicular to the gear axis of rotation. Stretches out the tooth shapes. Used to match helical spur gear pinions. Default: 0
// internal = If true, create a mask for difference()ing from something else.
// profile_shift = Profile shift factor x. Default: "auto"
// shaft_diam = If given, the diameter of the central shaft hole.
// mod = The module of the gear (pitch diameter / teeth)
// diam_pitch = The diametral pitch, or number of teeth per inch of pitch diameter. Note that the diametral pitch is a completely different thing than the pitch diameter.
// mod = The metric module/modulus of the gear, or mm of pitch diameter per tooth.
// pressure_angle = Controls how straight or bulged the tooth sides are. In degrees.
// profile_shift = Profile shift factor x. Default: "auto"
// shorten = Shorten gear tips by the module times this value. Needed for large profile shifted gears. Default: 0
// backlash = Gap between two meshing teeth, in the direction along the circumference of the pitch circle. Default: 0
// helical = Adjust teeth form (stretch out the teeth) to give the cross section of a gear with this helical angle. Default: 0
// hide = Number of teeth to delete to make this only a fraction of a circle
// gear_spin = Rotate gear and children around the gear center, regardless of how gear is anchored. Default: 0
// clearance = Gap between top of a tooth on one gear and bottom of valley on a meshing gear. Default: mod/4
// internal = If true, create a mask for difference()ing from something else.
// shaft_diam = If given, the diameter of the central shaft hole.
// atype = Set to "root", "tip" or "pitch" to determine anchoring circle. Default: "pitch"
// anchor = Translate so anchor point 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`
// Side Effects:
// If internal is true then the default tag is "remove"
// Anchor Types:
// root = anchor on the root circle
// pitch = anchor on the pitch circle (default)
// tip = anchor on the tip circle
// Example(2D): Typical Gear Shape
// spur_gear2d(circ_pitch=5, teeth=20, shaft_diam=5);
// Example(2D): By Metric Module
@ -951,6 +1008,7 @@ function spur_gear2d(
diam_pitch,
mod,
gear_spin = 0,
atype="pitch",
anchor = CENTER,
spin = 0
) = let(
@ -971,6 +1029,12 @@ function spur_gear2d(
assert(is_finite(gear_spin))
let(
pr = pitch_radius(circ_pitch, teeth, helical=helical),
or = outer_radius(circ_pitch, teeth, helical=helical, profile_shift=profile_shift, internal=internal,shorten=shorten),
rr = _root_radius(circ_pitch, teeth, clearance, profile_shift=profile_shift, internal=internal),
anchor_rad = atype=="pitch" ? pr
: atype=="tip" ? or
: atype=="root" ? rr
: assert(false,"atype must be one of \"root\", \"tip\" or \"pitch\""),
tooth = _gear_tooth_profile(
circ_pitch=circ_pitch,
teeth=teeth,
@ -992,7 +1056,7 @@ function spur_gear2d(
if (shaft_diam>0 && !hide)
reverse(circle(d=shaft_diam, $fn=max(16,segs(shaft_diam/2)))),
]
) reorient(anchor,spin, two_d=true, r=pr, p=rgn);
) reorient(anchor,spin, two_d=true, r=anchor_rad, p=rgn);
module spur_gear2d(
@ -1012,6 +1076,7 @@ module spur_gear2d(
diam_pitch,
mod,
gear_spin = 0,
atype="pitch",
anchor = CENTER,
spin = 0
) {
@ -1044,7 +1109,13 @@ module spur_gear2d(
shaft_diam = shaft_diam
);
pr = pitch_radius(circ_pitch, teeth, helical=helical);
attachable(anchor,spin, two_d=true, r=pr) {
or = outer_radius(circ_pitch, teeth, helical=helical, profile_shift=profile_shift, internal=internal,shorten=shorten);
rr = _root_radius(circ_pitch, teeth, clearance, profile_shift=profile_shift, internal=internal);
anchor_rad = atype=="pitch" ? pr
: atype=="tip" ? or
: atype=="root" ? rr
: assert(false,"atype must be one of \"root\", \"tip\" or \"pitch\"");
attachable(anchor,spin, two_d=true, r=anchor_rad) {
zrot(gear_spin) region(rgn);
union() {
$parent_gear_type = "spur2D";
@ -1268,7 +1339,7 @@ module ring_gear2d(
pitch,
diam_pitch,
mod,
gear_spin = 0,
gear_spin = 0,shorten=0,
anchor = CENTER,
spin = 0
) {
@ -1310,7 +1381,7 @@ module ring_gear2d(
pressure_angle = PA,
helical = helical,
clearance = clearance,
backlash = backlash,
backlash = backlash,shorten=shorten,
profile_shift = profile_shift,
internal = true
);
@ -1336,15 +1407,18 @@ module ring_gear2d(
// Description:
// This is used to create a 3D rack, which is a linear bar with teeth that a gear can roll along.
// A rack can mesh with any gear that has the same `pitch` and `pressure_angle`. A helical rack meshes with a gear with the opposite
// helical angle. The rack appears oriented with
// its teeth pointed UP, so it will need to be oriented to mesh with gears.
// The pitch line of the rack is aligned with the x axis.
// helical angle.
// When called as a function, returns a 3D [VNF](vnf.scad) for the rack.
// When called as a module, creates a 3D rack shape.
// .
// By default the rack has a backing whose height is equal to the height of the teeth. You can specify a different backing size
// or you can specify the total width of the rack (from the bottom of the rack to tooth tips) or the
// bottom point of the rack, which is the distance from the pitch line to the bottom of the rack.
// .
// The rack appears oriented with
// its teeth pointed UP, so to mesh with gears in the XY plane, use `orient=BACK` or `orient=FWD` and apply any desired rotation.
// The pitch line of the rack is aligned with the x axis, the TOP anchors are at the tips of the teeth and the BOTTOM anchors at
// the bottom of the backing. Note that for helical racks the corner anchors still point at 45 degr angles.
// Arguments:
// pitch = The pitch, or distance in mm between teeth along the rack. Matches up with circular pitch on a spur gear. Default: 5
// teeth = Total number of teeth along the rack. Default: 20
@ -1365,11 +1439,6 @@ module ring_gear2d(
// 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`
// Extra Anchors:
// "tip" = At the tips of the teeth, at the center of rack.
// "tip-left" = At the tips of the teeth, at the left end of the rack.
// "tip-right" = At the tips of the teeth, at the right end of the rack.
// "tip-back" = At the tips of the teeth, at the back of the rack.
// "tip-front" = At the tips of the teeth, at the front of the rack.
// "root" = At the base of the teeth, at the center of rack.
// "root-left" = At the base of the teeth, at the left end of the rack.
// "root-right" = At the base of the teeth, at the right end of the rack.
@ -1379,8 +1448,14 @@ module ring_gear2d(
// rack(pitch=5, teeth=10, thickness=5);
// Example(NoScales,VPT=[0.317577,3.42688,7.83665],VPR=[27.7,0,359.8],VPD=139.921): Rack for Helical Gear
// rack(pitch=5, teeth=10, thickness=5, backing=5, helical=30);
// Example(NoScales): Metric Rack, oriented BACK to align with a gear in default orientation
// Example(NoScales): Metric Rack, oriented BACK to align with a gear in default orientation. With profile shifting set to zero the gears mesh at their pitch circles.
// rack(mod=2, teeth=10, thickness=5, bottom=5, pressure_angle=14.5,orient=BACK);
// color("red") spur_gear(mod=2, teeth=18, thickness=5, pressure_angle=14.5,anchor=FRONT,profile_shift=0);
// Example(NoScales): Orienting the rack to the right using {zrot()}. In this case the gear has automatic profile shifting so we must use {{gear_dist()}} to correctly position the gear.
// zrot(-90)rack(mod=2, teeth=6, thickness=5, bottom=5, pressure_angle=14.5,orient=BACK);
// color("red")
// right(gear_dist(mod=2,0,12,pressure_angle=14.5))
// spur_gear(mod=2, teeth=12, thickness=5, pressure_angle=14.5);
// Example(NoScales,Anim,VPT=[0,0,12],VPD=100,Frames=18): Rack and Pinion with helical teeth
// teeth1 = 16; teeth2 = 16;
// pitch = 5; thick = 5; helical = 30;
@ -1453,24 +1528,24 @@ module rack(
: 2*d+a; // default case
l = teeth * trans_pitch;
anchors = [
named_anchor("tip", [0,0,a], BACK),
named_anchor("tip-left", [-l/2,0,a], LEFT),
named_anchor("tip-right", [ l/2,0,a], RIGHT),
named_anchor("tip-front", [0,-thickness/2,a], DOWN),
named_anchor("tip-back", [0, thickness/2,a], UP),
named_anchor("root", [0,0,-d], BACK),
named_anchor("root-left", [-l/2,0,-d], LEFT),
named_anchor("root-right", [ l/2,0,-d], RIGHT),
named_anchor("root-front", [0,-thickness/2,-d], DOWN),
named_anchor("root-back", [0, thickness/2,-d], UP),
named_anchor("root-front", [0,-thickness/2,-d], FWD),
named_anchor("root-back", [0, thickness/2,-d], BACK),
];
endfix = sin(helical)*thickness/2;
override = function(anchor)
anchor.z==1 ? [ [anchor.x*l/2-endfix*anchor.y,anchor.y*thickness/2,a], undef, undef]
: anchor.x!=0 ? [ [anchor.x*l/2-endfix*anchor.y,anchor.y*thickness/2,anchor.z*bottom], undef,undef]
: undef;
size = [l, thickness, 2*bottom];
attachable(anchor,spin,orient, size=size, anchors=anchors) {
attachable(anchor,spin,orient, size=size, anchors=anchors, override=override) {
right(gear_travel)
xrot(90) {
if (herringbone) {
zflip_copy()
skew(axz=-helical) down(0.01)
skew(axz=-helical)
linear_extrude(height=thickness/2, center=false, convexity=teeth*2) {
rack2d(
pitch = pitch,
@ -1611,6 +1686,9 @@ function rack(
// By default the rack has a backing whose height is equal to the height of the teeth. You can specify a different backing size
// or you can specify the total width of the rack (from the bottom of the rack to tooth tips) or the
// bottom point of the rack, which is the distance from the pitch line to the bottom of the rack.
// .
// The rack appears with its pitch line on top of the x axis. The BACK anchor refers to the tips of the teeth and the FRONT
// anchor refers to the front of the backing. You can use named anchors to access the roots of the teeth.
// Arguments:
// pitch = The pitch, or distance in mm between teeth along the rack. Matches up with circular pitch on a spur gear. Default: 5
// teeth = Total number of teeth along the rack
@ -1630,9 +1708,6 @@ function rack(
// anchor = Translate so anchor point 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`
// Extra Anchors:
// "tip" = At the tips of the teeth, at the center of rack.
// "tip-left" = At the tips of the teeth, at the left end of the rack.
// "tip-right" = At the tips of the teeth, at the right end of the rack.
// "root" = At the height of the teeth, at the center of rack.
// "root-left" = At the height of the teeth, at the left end of the rack.
// "root-right" = At the height of the teeth, at the right end of the rack.
@ -1730,14 +1805,16 @@ function rack2d(
]),
size=[l,2*bottom],
anchors = [
named_anchor("tip", [ 0, adendum,0], BACK),
named_anchor("tip-left", [-l/2, adendum,0], LEFT),
named_anchor("tip-right", [ l/2, adendum,0], RIGHT),
named_anchor("root", [ 0,-dedendum,0], BACK),
named_anchor("root-left", [-l/2,-dedendum,0], LEFT),
named_anchor("root-right", [ l/2,-dedendum,0], RIGHT),
],
override = [
[[0,1] , [[0,adendum]]],
[[1,1] , [[l/2,adendum]]],
[[-1,1] , [[-l/2,adendum]]],
]
) reorient(anchor,spin, two_d=true, size=size, anchors=anchors, p=path);
) reorient(anchor,spin, two_d=true, size=size, anchors=anchors, override=override, p=path);
@ -1796,14 +1873,16 @@ module rack2d(
);
size = [l, 2*bottom];
anchors = [
named_anchor("tip", [ 0, a,0], BACK),
named_anchor("tip-left", [-l/2, a,0], LEFT),
named_anchor("tip-right", [ l/2, a,0], RIGHT),
named_anchor("root", [ 0,-d,0], BACK),
named_anchor("root-left", [-l/2,-d,0], LEFT),
named_anchor("root-right", [ l/2,-d,0], RIGHT),
];
attachable(anchor,spin, two_d=true, size=size, anchors=anchors) {
override = [
[[0,1] , [[0,a]]],
[[1,1] , [[l/2,a]]],
[[-1,1] , [[-l/2,a]]],
];
attachable(anchor,spin, two_d=true, size=size, anchors=anchors, override=override) {
right(gear_travel) polygon(path);
children();
}
@ -3128,9 +3207,9 @@ function pitch_radius(
// Topics: Gears, Parts
// See Also: spur_gear(), diametral_pitch(), circular_pitch(), module_value(), pitch_radius(), outer_radius()
// Usage:
// or = outer_radius(circ_pitch, teeth, [helical=], [clearance=], [internal=], [profile_shift=]);
// or = outer_radius(mod=, teeth=, [helical=], [clearance=], [internal=], [profile_shift=]);
// or = outer_radius(diam_pitch=, teeth=, [helical=], [clearance=], [internal=], [profile_shift=]);
// or = outer_radius(circ_pitch, teeth, [helical=], [clearance=], [internal=], [profile_shift=], [shorten=]);
// or = outer_radius(mod=, teeth=, [helical=], [clearance=], [internal=], [profile_shift=], [shorten=]);
// or = outer_radius(diam_pitch=, teeth=, [helical=], [clearance=], [internal=], [profile_shift=], [shorten=]);
// Description:
// Calculates the outer radius for the gear. The gear fits entirely within a cylinder of this radius, unless
// it has been strongly profile shifted, in which case it will be undersized due to tip clipping.
@ -3669,7 +3748,7 @@ function get_profile_shift(desired,teeth1,teeth2,helical=0,pressure_angle=20,mod
// value to allow small undercutting, and only activate the profile shift for more extreme cases. Is is common
// practice to make gears with 15-17 teeth with undercutting with the standard 20 deg pressure angle.
// .
// The `get_min` argument returns the minimum profile shift needed to avoid undercutting regardless of the
// The `get_min` argument returns the minimum profile shift needed to avoid undercutting for the specified
// number of teeth. This will be a negative value for gears with a large number of teeth; such gears can
// be given a negative profile shift without undercutting.
// Arguments: