#!/usr/bin/env python3
'''
Copyright (C) 2007 Aaron Spike (aaron @ ekips.org)
Copyright (C) 2007 Tavmjong Bah (tavmjong @ free.fr)
Copyright (C) http://cnc-club.ru/forum/viewtopic.php?f=33&t=434&p=2594#p2500
Copyright (C) 2014 Jürgen Weigert (juewei@fabmail.org)
Copyright (C) 2020 Spadino (spada.andrea @ gmail DOT com)
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
2014-03-20 jw@suse.de 0.2 Option --accuracy=0 for automatic added.
2014-03-21 sent upstream: https://bugs.launchpad.net/inkscape/+bug/1295641
2014-03-21 jw@suse.de 0.3 Fixed center of rotation for gears with odd number of teeth.
2014-04-04 juewei 0.7 Revamped calc_unit_factor().
2014-04-05 juewei 0.7a Correctly positioned rack gear.
The geometry above the meshing line is wrong.
2014-04-06 juewei 0.7b Undercut detection added. Reference:
http://nptel.ac.in/courses/IIT-MADRAS/Machine_Design_II/pdf/2_2.pdf
Manually merged https://github.com/jnweiger/inkscape-gears-dev/pull/15
2014-04-07 juewei 0.7c Manually merged https://github.com/jnweiger/inkscape-gears-dev/pull/17
2014-04-09 juewei 0.8 Fixed https://github.com/jnweiger/inkscape-gears-dev/issues/19
Ring gears are ready for production now. Thanks neon22 for driving this.
Profile shift implemented (Advanced Tab), fixing
https://github.com/jnweiger/inkscape-gears-dev/issues/9
2015-05-29 juewei 0.9 ported to inkscape 0.91
AttributeError: 'module' object inkex has no attribute 'uutounit
Fixed https://github.com/jnweiger/inkscape-gears-dev
2020-7-4 spadino 1.0 ported to inkscape 1.0
'''
import inkex
from lxml import etree
from os import devnull # for debugging
from math import pi, cos, sin, tan, radians, degrees, ceil, asin, acos, sqrt
two_pi = 2 * pi
__version__ = '1.0'
def uutounit(self,nn,uu):
return self.svg.uutounit(nn,uu)
def linspace(a,b,n):
""" return list of linear interp of a to b in n steps
- if a and b are ints - you'll get an int result.
- n must be an integer
"""
return [a+x*(b-a)/(n-1) for x in range(0,n)]
def involute_intersect_angle(Rb, R):
" "
Rb, R = float(Rb), float(R)
return (sqrt(R**2 - Rb**2) / (Rb)) - (acos(Rb / R))
def point_on_circle(radius, angle):
" return xy coord of the point at distance radius from origin at angle "
x = radius * cos(angle)
y = radius * sin(angle)
return (x, y)
def points_to_bbox(p):
""" from a list of points (x,y pairs)
- return the lower-left xy and upper-right xy
"""
llx = urx = p[0][0]
lly = ury = p[0][1]
for x in p[1:]:
if x[0] < llx: llx = x[0]
elif x[0] > urx: urx = x[0]
if x[1] < lly: lly = x[1]
elif x[1] > ury: ury = x[1]
return (llx, lly, urx, ury)
def points_to_bbox_center(p):
""" from a list of points (x,y pairs)
- find midpoint of bounding box around all points
- return (x,y)
"""
bbox = points_to_bbox(p)
return ((bbox[0]+bbox[2])/2.0, (bbox[1]+bbox[3])/2.0)
def points_to_svgd(p):
" convert list of points into a closed SVG path list"
f = p[0]
p = p[1:]
svgd = 'M%.4f,%.4f' % f
for x in p:
svgd += 'L%.4f,%.4f' % x
svgd += 'z'
return svgd
def draw_SVG_circle(parent, r, cx, cy, name, style):
" add an SVG circle entity to parent "
circ_attribs = {'style': str(inkex.Style(style)),
'cx': str(cx), 'cy': str(cy),
'r': str(r),
inkex.addNS('label','inkscape'):name}
circle = etree.SubElement(parent, inkex.addNS('circle','svg'), circ_attribs )
### Undercut support functions
def undercut_min_teeth(pitch_angle, k=1.0):
""" computes the minimum tooth count for a
spur gear so that no undercut with the given pitch_angle (in deg)
and an addendum = k * metric_module, where 0 < k < 1
Note:
The return value should be rounded upwards for perfect safety. E.g.
min_teeth = int(math.ceil(undercut_min_teeth(20.0))) # 18, not 17
"""
x = sin(radians(pitch_angle))
return 2*k /(x*x)
def undercut_max_k(teeth, pitch_angle=20.0):
""" computes the maximum k value for a given teeth count and pitch_angle
so that no undercut occurs.
"""
x = sin(radians(pitch_angle))
return 0.5 * teeth * x * x
def undercut_min_angle(teeth, k=1.0):
""" computes the minimum pitch angle, to that the given teeth count (and
profile shift) cause no undercut.
"""
return degrees(asin(min(0.856, sqrt(2.0*k/teeth)))) # max 59.9 deg
def have_undercut(teeth, pitch_angle=20.0, k=1.0):
""" returns true if the specified number of teeth would
cause an undercut.
"""
return (teeth < undercut_min_teeth(pitch_angle, k))
## gather all basic gear calculations in one place
def gear_calculations(num_teeth, circular_pitch, pressure_angle, clearance=0, ring_gear=False, profile_shift=0.):
""" Put base calcs for spur/ring gears in one place.
- negative profile shifting helps against undercut.
"""
diametral_pitch = pi / circular_pitch
pitch_diameter = num_teeth / diametral_pitch
pitch_radius = pitch_diameter / 2.0
addendum = 1 / diametral_pitch
#dedendum = 1.157 / diametral_pitch # auto calc clearance
dedendum = addendum
dedendum *= 1+profile_shift
addendum *= 1-profile_shift
if ring_gear:
addendum = addendum + clearance # our method
else:
dedendum = dedendum + clearance # our method
#
#
base_radius = pitch_diameter * cos(radians(pressure_angle)) / 2.0
outer_radius = pitch_radius + addendum
root_radius = pitch_radius - dedendum
# Tooth thickness: Tooth width along pitch circle.
tooth_thickness = ( pi * pitch_diameter ) / ( 2.0 * num_teeth )
# we don't use these
working_depth = 2 / diametral_pitch
whole_depth = 2.157 / diametral_pitch
#outside_diameter = (num_teeth + 2) / diametral_pitch
#
return (pitch_radius, base_radius,
addendum, dedendum, outer_radius, root_radius,
tooth_thickness
)
def generate_rack_points(tooth_count, pitch, addendum, pressure_angle,
rack_base_height, tab_length, clearance=0, draw_guides=False):
""" Return path (suitable for svg) of the Rack gear.
- rack gear uses straight sides
- involute on a circle of infinite radius is a simple linear ramp
- the meshing circle touches at y = 0,
- the highest elevation of the teeth is at y = +addendum
- the lowest elevation of the teeth is at y = -addendum-clearance
- the rack_base_height extends downwards from the lowest elevation.
- we generate this middle tooth exactly centered on the y=0 line.
(one extra tooth on the right hand side, if number of teeth is even)
"""
spacing = 0.5 * pitch # rolling one pitch distance on the spur gear pitch_diameter.
# roughly center rack in drawing, exact position is so that it meshes
# nicely with the spur gear.
# -0.5*spacing has a gap in the center.
# +0.5*spacing has a tooth in the center.
fudge = +0.5 * spacing
tas = tan(radians(pressure_angle)) * addendum
tasc = tan(radians(pressure_angle)) * (addendum+clearance)
base_top = addendum+clearance
base_bot = addendum+clearance+rack_base_height
x_lhs = -pitch * int(0.5*tooth_count-.5) - spacing - tab_length - tasc + fudge
#inkex.utils.debug("angle=%s spacing=%s"%(pressure_angle, spacing))
# Start with base tab on LHS
points = [] # make list of points
points.append((x_lhs, base_bot))
points.append((x_lhs, base_top))
x = x_lhs + tab_length+tasc
# An involute on a circle of infinite radius is a simple linear ramp.
# We need to add curve at bottom and use clearance.
for i in range(tooth_count):
# move along path, generating the next 'tooth'
# pitch line is at y=0. the left edge hits the pitch line at x
points.append((x-tasc, base_top))
points.append((x+tas, -addendum))
points.append((x+spacing-tas, -addendum))
points.append((x+spacing+tasc, base_top))
x += pitch
x -= spacing # remove last adjustment
# add base on RHS
x_rhs = x+tasc+tab_length
points.append((x_rhs, base_top))
points.append((x_rhs, base_bot))
# We don't close the path here. Caller does it.
# points.append((x_lhs, base_bot))
# Draw line representing the pitch circle of infinite diameter
guide_path = None
if draw_guides:
p = []
p.append( (x_lhs + 0.5 * tab_length, 0) )
p.append( (x_rhs - 0.5 * tab_length, 0) )
guide_path = points_to_svgd(p)
# return points ready for use in an SVG 'path'
return (points, guide_path)
def generate_spur_points(teeth, base_radius, pitch_radius, outer_radius, root_radius, accuracy_involute, accuracy_circular):
""" given a set of core gear params
- generate the svg path for the gear
"""
half_thick_angle = two_pi / (4.0 * teeth ) #?? = pi / (2.0 * teeth)
pitch_to_base_angle = involute_intersect_angle( base_radius, pitch_radius )
pitch_to_outer_angle = involute_intersect_angle( base_radius, outer_radius ) - pitch_to_base_angle
start_involute_radius = max(base_radius, root_radius)
radii = linspace(start_involute_radius, outer_radius, accuracy_involute)
angles = [involute_intersect_angle(base_radius, r) for r in radii]
centers = [(x * two_pi / float( teeth) ) for x in range( teeth ) ]
points = []
for c in centers:
# Angles
pitch1 = c - half_thick_angle
base1 = pitch1 - pitch_to_base_angle
offsetangles1 = [ base1 + x for x in angles]
points1 = [ point_on_circle( radii[i], offsetangles1[i]) for i in range(0,len(radii)) ]
pitch2 = c + half_thick_angle
base2 = pitch2 + pitch_to_base_angle
offsetangles2 = [ base2 - x for x in angles]
points2 = [ point_on_circle( radii[i], offsetangles2[i]) for i in range(0,len(radii)) ]
points_on_outer_radius = [ point_on_circle(outer_radius, x) for x in linspace(offsetangles1[-1], offsetangles2[-1], accuracy_circular) ]
if root_radius > base_radius:
pitch_to_root_angle = pitch_to_base_angle - involute_intersect_angle(base_radius, root_radius )
root1 = pitch1 - pitch_to_root_angle
root2 = pitch2 + pitch_to_root_angle
points_on_root = [point_on_circle (root_radius, x) for x in linspace(root2, root1+(two_pi/float(teeth)), accuracy_circular) ]
p_tmp = points1 + points_on_outer_radius[1:-1] + points2[::-1] + points_on_root[1:-1] # [::-1] reverses list; [1:-1] removes first and last element
else:
points_on_root = [point_on_circle (root_radius, x) for x in linspace(base2, base1+(two_pi/float(teeth)), accuracy_circular) ]
p_tmp = points1 + points_on_outer_radius[1:-1] + points2[::-1] + points_on_root # [::-1] reverses list
points.extend( p_tmp )
return (points)
def generate_spokes_path(root_radius, spoke_width, spoke_count, mount_radius, mount_hole,
unit_factor, unit_label):
""" given a set of constraints
- generate the svg path for the gear spokes
- lies between mount_radius (inner hole) and root_radius (bottom of the teeth)
- spoke width also defines the spacing at the root_radius
- mount_radius is adjusted so that spokes fit if there is room
- if no room (collision) then spokes not drawn
"""
# Spokes
collision = False # assume we draw spokes
messages = [] # messages to send back about changes.
path = ''
r_outer = root_radius - spoke_width
# checks for collision with spokes
# check for mount hole collision with inner spokes
if mount_radius <= mount_hole/2:
adj_factor = (r_outer - mount_hole/2) / 5
if adj_factor < 0.1:
# not enough reasonable room
collision = True
else:
mount_radius = mount_hole/2 + adj_factor # small fix
messages.append("Mount support too small. Auto increased to %2.2f%s." % (mount_radius/unit_factor*2, unit_label))
# then check to see if cross-over on spoke width
if spoke_width * spoke_count +0.5 >= two_pi * mount_radius:
adj_factor = 1.2 # wrong value. its probably one of the points distances calculated below
mount_radius += adj_factor
messages.append("Too many spokes. Increased Mount support by %2.3f%s" % (adj_factor/unit_factor, unit_label))
# check for collision with outer rim
if r_outer <= mount_radius:
# not enough room to draw spokes so cancel
collision = True
if collision: # don't draw spokes if no room.
messages.append("Not enough room for Spokes. Decrease Spoke width.")
else: # draw spokes
for i in range(spoke_count):
points = []
start_a, end_a = i * two_pi / spoke_count, (i+1) * two_pi / spoke_count
# inner circle around mount
asin_factor = spoke_width/mount_radius/2
# check if need to clamp radius
asin_factor = max(-1.0, min(1.0, asin_factor)) # no longer needed - resized above
a = asin(asin_factor)
points += [ point_on_circle(mount_radius, start_a + a), point_on_circle(mount_radius, end_a - a)]
# is inner circle too small
asin_factor = spoke_width/r_outer/2
# check if need to clamp radius
asin_factor = max(-1.0, min(1.0, asin_factor)) # no longer needed - resized above
a = asin(asin_factor)
points += [point_on_circle(r_outer, end_a - a), point_on_circle(r_outer, start_a + a) ]
path += (
"M %f,%f" % points[0] +
"A %f,%f %s %s %s %f,%f" % tuple((mount_radius, mount_radius, 0, 0 if spoke_count!=1 else 1, 1 ) + points[1]) +
"L %f,%f" % points[2] +
"A %f,%f %s %s %s %f,%f" % tuple((r_outer, r_outer, 0, 0 if spoke_count!=1 else 1, 0 ) + points[3]) +
"Z"
)
return (path, messages)
class Gears(inkex.EffectExtension):
def __init__(self):
inkex.Effect.__init__(self)
# an alternate way to get debug info:
# could use inkex.utils.debug(string) instead...
# try:
# self.tty = open("/dev/tty", 'w')
# except:
# self.tty = open(devnull, 'w') # '/dev/null' for POSIX, 'nul' for Windows.
# # print >>self.tty, "gears-dev " + __version__
self.arg_parser.add_argument("-t", "--teeth", type=int, default=24, help="Number of teeth")
self.arg_parser.add_argument("-s", "--system", default='CP', help="Select system: 'CP' (Cyclic Pitch (default)), 'DP' (Diametral Pitch), 'MM' (Metric Module)")
self.arg_parser.add_argument("-d", "--dimension", type=float, default=1.0, help="Tooth size, depending on system (which defaults to CP)")
self.arg_parser.add_argument("-a", "--angle", type=float, default=20.0, help="Pressure Angle (common values: 14.5, 20, 25 degrees)")
self.arg_parser.add_argument("-p", "--profile_shift", type=float, default=20.0, help="Profile shift [in percent of the module]. Negative values help against undercut")
self.arg_parser.add_argument("-u", "--units", default='mm', help="Units this dialog is using")
self.arg_parser.add_argument("-A", "--accuracy", type=int, default=0, help="Accuracy of involute: automatic: 5..20 (default), best: 20(default), medium 10, low: 5; good acuracy is important with a low tooth count")
# Clearance: Radial distance between top of tooth on one gear to bottom of gap on another.
self.arg_parser.add_argument("-cl", "--clearance", type=float, default=0.0, help="Clearance between bottom of gap of this gear and top of tooth of another")
self.arg_parser.add_argument("-an", "--annotation", type=inkex.Boolean, default=False, help="Draw annotation text")
self.arg_parser.add_argument("-i", "--internal_ring", type=inkex.Boolean, default=False, help="Ring (or Internal) gear style (default: normal spur gear)")
self.arg_parser.add_argument("-mh", "--mount_hole", type=float, default=5, help="Mount hole diameter")
self.arg_parser.add_argument("-md", "--mount_diameter", type=float, default=15, help="Mount support diameter")
self.arg_parser.add_argument("-sc", "--spoke_count", type=int, default=3, help="Spokes count")
self.arg_parser.add_argument("-sw", "--spoke_width", type=float, default=5, help="Spoke width")
self.arg_parser.add_argument("-hr", "--holes_rounding", type=float, default=5, help="Holes rounding")
self.arg_parser.add_argument("-at", "--active_tab", default='', help="Active tab. Not used now.")
self.arg_parser.add_argument("-x", "--centercross", type=inkex.Boolean, default=False, help="Draw cross in center")
self.arg_parser.add_argument("-c", "--pitchcircle", type=inkex.Boolean, default=False, help="Draw pitch circle (for mating)")
self.arg_parser.add_argument("-r", "--draw_rack", type=inkex.Boolean, default=False, help="Draw rack gear instead of spur gear")
self.arg_parser.add_argument("-rl", "--rack_teeth_length", type=int, default=12, help="Length (in teeth) of rack")
self.arg_parser.add_argument("-rh", "--rack_base_height", type=float, default=8, help="Height of base of rack")
self.arg_parser.add_argument("-rt", "--rack_base_tab", type=float, default=14, help="Length of tabs on ends of rack")
self.arg_parser.add_argument("-ua", "--undercut_alert", type=inkex.Boolean, default=False, help="Let the user confirm a warning dialog if undercut occurs. This dialog also shows helpful hints against undercut")
def add_text(self, node, text, position, text_height=12):
""" Create and insert a single line of text into the svg under node.
- use 'text' type and label as anootation
- where color is Ponoko Orange - so ignored when lasercutting
"""
line_style = {'font-size': '%dpx' % text_height, 'font-style':'normal', 'font-weight': 'normal',
'fill': '#F6921E', 'font-family': 'Bitstream Vera Sans,sans-serif',
'text-anchor': 'middle', 'text-align': 'center'}
line_attribs = {inkex.addNS('label','inkscape'): 'Annotation',
'style': str(inkex.Style(line_style)),
'x': str(position[0]),
'y': str((position[1] + text_height) * 1.2)
}
line = etree.SubElement(node, inkex.addNS('text','svg'), line_attribs)
line.text = text
def calc_unit_factor(self):
""" return the scale factor for all dimension conversions.
- The document units are always irrelevant as
everything in inkscape is expected to be in 90dpi pixel units
"""
# namedView = self.document.getroot().find(inkex.addNS('namedview', 'sodipodi'))
# doc_units = uutounit(self, 1.0, namedView.get(inkex.addNS('document-units', 'inkscape')))
dialog_units = uutounit(self, 1.0, self.options.units)
unit_factor = 1.0 / dialog_units
return unit_factor
def calc_circular_pitch(self):
""" We use math based on circular pitch.
Expressed in inkscape units which is 90dpi 'pixel' units.
"""
dimension = self.options.dimension
# print >> self.tty, "unit_factor=%s, doc_units=%s, dialog_units=%s (%s), system=%s" % (unit_factor, doc_units, dialog_units, self.options.units, self.options.system)
if self.options.system == 'CP': # circular pitch
circular_pitch = dimension
elif self.options.system == 'DP': # diametral pitch
circular_pitch = pi / dimension
elif self.options.system == 'MM': # module (metric)
circular_pitch = dimension * pi / 25.4
else:
inkex.utils.debug("unknown system '%s', try CP, DP, MM" % self.options.system)
# circular_pitch defines the size in inches.
# We divide the internal inch factor (px = 90dpi), to remove the inch
# unit.
# The internal inkscape unit is always px,
# it is independent of the doc_units!
return circular_pitch / uutounit(self, 1.0, 'in')
def effect(self):
""" Calculate Gear factors from inputs.
- Make list of radii, angles, and centers for each tooth and
iterate through them
- Turn on other visual features e.g. cross, rack, annotations, etc
"""
path_stroke = '#000000' # might expose one day
path_fill = 'none' # no fill - just a line
path_stroke_width = uutounit(self, 0.1, 'mm') # might expose one day
path_stroke_light = uutounit(self, 0.05, 'mm') # guides are thinner
#
warnings = [] # list of extra messages to be shown in annotations
# calculate unit factor for units defined in dialog.
unit_factor = self.calc_unit_factor()
# User defined options
teeth = self.options.teeth
# Angle of tangent to tooth at circular pitch wrt radial line.
angle = self.options.angle
# Clearance: Radial distance between top of tooth on one gear to
# bottom of gap on another.
clearance = self.options.clearance * unit_factor
mount_hole = self.options.mount_hole * unit_factor
# for spokes
mount_radius = self.options.mount_diameter * 0.5 * unit_factor
spoke_count = self.options.spoke_count
spoke_width = self.options.spoke_width * unit_factor
holes_rounding = self.options.holes_rounding * unit_factor # unused
# visible guide lines
centercross = self.options.centercross # draw center or not (boolean)
pitchcircle = self.options.pitchcircle # draw pitch circle or not (boolean)
# Accuracy of teeth curves
accuracy_involute = 20 # Number of points of the involute curve
accuracy_circular = 9 # Number of points on circular parts
if self.options.accuracy is not None:
if self.options.accuracy == 0:
# automatic
if teeth < 10: accuracy_involute = 20
elif teeth < 30: accuracy_involute = 12
else: accuracy_involute = 6
else:
accuracy_involute = self.options.accuracy
accuracy_circular = max(3, int(accuracy_involute/2) - 1) # never less than three
# print >>self.tty, "accuracy_circular=%s accuracy_involute=%s" % (accuracy_circular, accuracy_involute)
# Pitch (circular pitch): Length of the arc from one tooth to the next)
# Pitch diameter: Diameter of pitch circle.
pitch = self.calc_circular_pitch()
# Replace section below with this call to get the combined gear_calculations() above
(pitch_radius, base_radius, addendum, dedendum,
outer_radius, root_radius, tooth) = gear_calculations(teeth, pitch, angle, clearance, self.options.internal_ring, self.options.profile_shift*0.01)
# Detect Undercut of teeth
## undercut = int(ceil(undercut_min_teeth( angle )))
## needs_undercut = teeth < undercut #? no longer needed ?
if have_undercut(teeth, angle, 1.0):
min_teeth = int(ceil(undercut_min_teeth(angle, 1.0)))
min_angle = undercut_min_angle(teeth, 1.0) + .1
max_k = undercut_max_k(teeth, angle)
msg = "Undercut Warning: This gear (%d teeth) will not work well.\nTry tooth count of %d or more,\nor a pressure angle of %.1f [deg] or more,\nor try a profile shift of %d %%.\nOr other decent combinations." % (teeth, min_teeth, min_angle, int(100. * max_k) - 100.)
# alas annotation cannot handle the degree symbol. Also it ignore
# newlines.
# so split and make a list
warnings.extend(msg.split("\n"))
#if self.options.undercut_alert:
# inkex.utils.debug(msg)
#else:
# print >> self.tty, msg
# All base calcs done. Start building gear
points = generate_spur_points(teeth, base_radius, pitch_radius, outer_radius, root_radius, accuracy_involute, accuracy_circular)
## half_thick_angle = two_pi / (4.0 * teeth ) #?? = pi / (2.0 * teeth)
## pitch_to_base_angle = involute_intersect_angle( base_radius, pitch_radius )
## pitch_to_outer_angle = involute_intersect_angle( base_radius, outer_radius ) - pitch_to_base_angle
##
## start_involute_radius = max(base_radius, root_radius)
## radii = linspace(start_involute_radius, outer_radius, accuracy_involute)
## angles = [involute_intersect_angle(base_radius, r) for r in radii]
##
## centers = [(x * two_pi / float( teeth) ) for x in range( teeth ) ]
## points = []
##
## for c in centers:
## # Angles
## pitch1 = c - half_thick_angle
## base1 = pitch1 - pitch_to_base_angle
## offsetangles1 = [ base1 + x for x in angles]
## points1 = [ point_on_circle( radii[i], offsetangles1[i]) for i in range(0,len(radii)) ]
##
## pitch2 = c + half_thick_angle
## base2 = pitch2 + pitch_to_base_angle
## offsetangles2 = [ base2 - x for x in angles]
## points2 = [ point_on_circle( radii[i], offsetangles2[i]) for i in range(0,len(radii)) ]
##
## points_on_outer_radius = [ point_on_circle(outer_radius, x) for x in linspace(offsetangles1[-1], offsetangles2[-1], accuracy_circular) ]
##
## if root_radius > base_radius:
## pitch_to_root_angle = pitch_to_base_angle - involute_intersect_angle(base_radius, root_radius )
## root1 = pitch1 - pitch_to_root_angle
## root2 = pitch2 + pitch_to_root_angle
## points_on_root = [point_on_circle (root_radius, x) for x in linspace(root2, root1+(two_pi/float(teeth)), accuracy_circular) ]
## p_tmp = points1 + points_on_outer_radius[1:-1] + points2[::-1] + points_on_root[1:-1] # [::-1] reverses list; [1:-1] removes first and last element
## else:
## points_on_root = [point_on_circle (root_radius, x) for x in linspace(base2, base1+(two_pi/float(teeth)), accuracy_circular) ]
## p_tmp = points1 + points_on_outer_radius[1:-1] + points2[::-1] + points_on_root # [::-1] reverses list
##
## points.extend( p_tmp )
path = points_to_svgd( points )
bbox_center = points_to_bbox_center( points )
# Spokes (add to current path)
if not self.options.internal_ring: # only draw internals if spur gear
spokes_path, msg = generate_spokes_path(root_radius, spoke_width, spoke_count, mount_radius, mount_hole,
unit_factor, self.options.units)
warnings.extend(msg)
path += spokes_path
# Draw mount hole
# A : rx,ry x-axis-rotation, large-arch-flag, sweepflag x,y
r = mount_hole / 2
path += (
"M %f,%f" % (0,r) +
"A %f,%f %s %s %s %f,%f" % (r,r, 0,0,0, 0,-r) +
"A %f,%f %s %s %s %f,%f" % (r,r, 0,0,0, 0,r)
)
else:
# its a ring gear
# which only has an outer ring where width = spoke width
r = outer_radius + spoke_width
path += (
"M %f,%f" % (0,r) +
"A %f,%f %s %s %s %f,%f" % (r,r, 0,0,0, 0,-r) +
"A %f,%f %s %s %s %f,%f" % (r,r, 0,0,0, 0,r)
)
# Embed gear in group to make animation easier:
# Translate group, Rotate path.
t = 'translate(' + str( self.svg.namedview.center[0] ) + ',' + str( self.svg.namedview.center[1] ) + ')'
g_attribs = { inkex.addNS('label','inkscape'):'Gear' + str( teeth ),
inkex.addNS('transform-center-x','inkscape'): str(-bbox_center[0]),
inkex.addNS('transform-center-y','inkscape'): str(-bbox_center[1]),
'transform':t,
'info':'N:'+str(teeth)+'; Pitch:'+ str(pitch) + '; Pressure Angle: '+str(angle) }
# add the group to the current layer
g = etree.SubElement(self.svg.get_current_layer(), 'g', g_attribs )
# Create gear path under top level group
style = { 'stroke': path_stroke, 'fill': path_fill, 'stroke-width': path_stroke_width }
gear_attribs = { 'style': str(inkex.Style(style)), 'd': path }
gear = etree.SubElement(g, inkex.addNS('path','svg'), gear_attribs )
# Add center
if centercross:
style = {'stroke': path_stroke, 'fill': path_fill,
'stroke-width': path_stroke_light}
cs = str(pitch / 3) # centercross length
d = 'M-'+cs+',0L'+cs+',0M0,-'+cs+'L0,'+cs # 'M-10,0L10,0M0,-10L0,10'
center_attribs = {inkex.addNS('label', 'inkscape'): 'Center cross',
'style': str(inkex.Style(style)), 'd': d}
center = etree.SubElement(
g, inkex.addNS('path', 'svg'), center_attribs)
# Add pitch circle (for mating)
if pitchcircle:
style = { 'stroke': path_stroke, 'fill': path_fill, 'stroke-width': path_stroke_light }
draw_SVG_circle(g, pitch_radius, 0, 0, 'Pitch circle', style)
# Add Rack (below)
if self.options.draw_rack:
rack_base_height = self.options.rack_base_height * unit_factor
tab_width = self.options.rack_base_tab * unit_factor
tooth_count = self.options.rack_teeth_length
(points, guide_path) = generate_rack_points(tooth_count, pitch, addendum, angle,
rack_base_height, tab_width, clearance, pitchcircle)
path = points_to_svgd(points)
# position below Gear, so that it meshes nicely
# xoff = 0 ## if teeth % 4 == 2.
# xoff = -0.5*pitch ## if teeth % 4 == 0.
# xoff = -0.75*pitch ## if teeth % 4 == 3.
# xoff = -0.25*pitch ## if teeth % 4 == 1.
xoff = (-0.5, -0.25, 0, -0.75)[teeth % 4] * pitch
t = 'translate(' + str( xoff ) + ',' + str( pitch_radius ) + ')'
g_attribs = { inkex.addNS('label', 'inkscape'): 'RackGear' + str(tooth_count),
'transform': t }
rack = etree.SubElement(g, 'g', g_attribs)
# Create SVG Path for gear
style = {'stroke': path_stroke, 'fill': 'none', 'stroke-width': path_stroke_width }
gear_attribs = { 'style': str(inkex.Style(style)), 'd': path }
gear = etree.SubElement(
rack, inkex.addNS('path', 'svg'), gear_attribs)
if guide_path is not None:
style2 = { 'stroke': path_stroke, 'fill': 'none', 'stroke-width': path_stroke_light }
gear_attribs2 = { 'style': str(inkex.Style(style2)), 'd': guide_path }
gear = etree.SubElement(
rack, inkex.addNS('path', 'svg'), gear_attribs2)
# Add Annotations (above)
if self.options.annotation:
outer_dia = outer_radius * 2
if self.options.internal_ring:
outer_dia += 2 * spoke_width
notes = []
notes.extend(warnings)
#notes.append('Document (%s) scale conversion = %2.4f' % (self.document.getroot().find(inkex.addNS('namedview', 'sodipodi')).get(inkex.addNS('document-units', 'inkscape')), unit_factor))
notes.extend(['Teeth: %d CP: %2.4f(%s) ' % (teeth, pitch / unit_factor, self.options.units),
'DP: %2.3f Module: %2.4f' % (pi / pitch * unit_factor, pitch / pi * 25.4),
'Pressure Angle: %2.2f degrees' % (angle),
'Pitch diameter: %2.3f %s' % (pitch_radius * 2 / unit_factor, self.options.units),
'Outer diameter: %2.3f %s' % (outer_dia / unit_factor, self.options.units),
'Base diameter: %2.3f %s' % (base_radius * 2 / unit_factor, self.options.units)#,
#'Addendum: %2.4f %s' % (addendum / unit_factor, self.options.units),
#'Dedendum: %2.4f %s' % (dedendum / unit_factor, self.options.units)
])
# text height relative to gear size.
# ranges from 10 to 22 over outer radius size 60 to 360
text_height = max(10, min(10+(outer_dia-60)/24, 22))
# position above
y = - outer_radius - (len(notes)+1) * text_height * 1.2
for note in notes:
self.add_text(g, note, [0,y], text_height)
y += text_height * 1.2
if __name__ == '__main__':
Gears().run()