# Copyright (C) 2007 Aaron Spike (aaron @ ekips.org)
# Copyright (C) 2007 Tavmjong Bah (tavmjong @ free.fr)
# Copyright (C) https://cnc-club.ru/forum/viewtopic.php?f=33&t=434&p=2594#p2500
# Copyright (C) 2014 Jürgen Weigert (juewei@fabmail.org)
#
# 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:
# https://web.archive.org/web/20140801105942/https://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
from math import acos, asin, ceil, cos, degrees, pi, radians, sin, sqrt, tan
from os import devnull # for debugging
two_pi = 2 * pi
import argparse
from boxes.vectors import vdiff, vlength
__version__ = '0.9'
[docs]
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)]
[docs]
def involute_intersect_angle(Rb, R):
Rb, R = float(Rb), float(R)
return (sqrt(R**2 - Rb**2) / (Rb)) - (acos(Rb / R))
[docs]
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)
### Undercut support functions
[docs]
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 = max(sin(radians(pitch_angle)), 0.01)
return 2*k /(x*x)
[docs]
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 = max(sin(radians(pitch_angle)), 0.01)
return 0.5 * teeth * x * x
[docs]
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
[docs]
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
[docs]
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 = 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 )
return (pitch_radius, base_radius,
addendum, dedendum, outer_radius, root_radius,
tooth_thickness
)
[docs]
def generate_rack_points(tooth_count, pitch, addendum, pressure_angle,
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 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.
if tab_length <= 0.0:
tab_length = 1E-8
tas = tan(radians(pressure_angle)) * addendum
tasc = tan(radians(pressure_angle)) * (addendum+clearance)
base_top = addendum+clearance
base_bot = addendum+clearance+base_height
x_lhs = -pitch * 0.5*tooth_count - tab_length
# 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
# 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
p = []
if draw_guides:
p.append( (x_lhs + 0.5 * tab_length, 0) )
p.append( (x_rhs - 0.5 * tab_length, 0) )
return (points, p)
[docs]
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)
[docs]
def inkbool(val):
return val not in ("False", False, "0", 0, "None", None)
[docs]
class OptionParser(argparse.ArgumentParser):
types = {
"int" : int,
"float" : float,
"string" : str,
"inkbool" : inkbool,
}
[docs]
def add_option(self, short, long_, **kw):
kw["type"] = self.types[kw["type"]]
names = []
if short:
names.append("-" + short.replace("-", "_")[1:])
if long_:
names.append("--" + long_.replace("-", "_")[2:])
self.add_argument(*names, **kw)
[docs]
class Gears():
def __init__(self, boxes, **kw) -> None:
# an alternate way to get debug info:
# could use inkex.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.boxes = boxes
self.OptionParser = OptionParser()
self.OptionParser.add_option("-t", "--teeth",
action="store", type="int",
dest="teeth", default=24,
help="Number of teeth")
self.OptionParser.add_option("-s", "--system",
action="store", type="string",
dest="system", default='MM',
help="Select system: 'CP' (Cyclic Pitch (default)), 'DP' (Diametral Pitch), 'MM' (Metric Module)")
self.OptionParser.add_option("-d", "--dimension",
action="store", type="float",
dest="dimension", default=1.0,
help="Tooth size, depending on system (which defaults to CP)")
self.OptionParser.add_option("-a", "--angle",
action="store", type="float",
dest="angle", default=20.0,
help="Pressure Angle (common values: 14.5, 20, 25 degrees)")
self.OptionParser.add_option("-p", "--profile-shift",
action="store", type="float",
dest="profile_shift", default=20.0,
help="Profile shift [in percent of the module]. Negative values help against undercut")
self.OptionParser.add_option("-u", "--units",
action="store", type="string",
dest="units", default='mm',
help="Units this dialog is using")
self.OptionParser.add_option("-A", "--accuracy",
action="store", type="int",
dest="accuracy", default=0,
help="Accuracy of involute: automatic: 5..20 (default), best: 20(default), medium 10, low: 5; good accuracy is important with a low tooth count")
# Clearance: Radial distance between top of tooth on one gear to bottom of gap on another.
self.OptionParser.add_option("", "--clearance",
action="store", type="float",
dest="clearance", default=0.0,
help="Clearance between bottom of gap of this gear and top of tooth of another")
self.OptionParser.add_option("", "--annotation",
action="store", type="inkbool",
dest="annotation", default=False,
help="Draw annotation text")
self.OptionParser.add_option("-i", "--internal-ring",
action="store", type="inkbool",
dest="internal_ring", default=False,
help="Ring (or Internal) gear style (default: normal spur gear)")
self.OptionParser.add_option("", "--mount-hole",
action="store", type="float",
dest="mount_hole", default=0.,
help="Mount hole diameter")
self.OptionParser.add_option("", "--mount-diameter",
action="store", type="float",
dest="mount_diameter", default=15,
help="Mount support diameter")
self.OptionParser.add_option("", "--spoke-count",
action="store", type="int",
dest="spoke_count", default=3,
help="Spokes count")
self.OptionParser.add_option("", "--spoke-width",
action="store", type="float",
dest="spoke_width", default=5,
help="Spoke width")
self.OptionParser.add_option("", "--holes-rounding",
action="store", type="float",
dest="holes_rounding", default=5,
help="Holes rounding")
self.OptionParser.add_option("", "--active-tab",
action="store", type="string",
dest="active_tab", default='',
help="Active tab. Not used now.")
self.OptionParser.add_option("-x", "--centercross",
action="store", type="inkbool",
dest="centercross", default=False,
help="Draw cross in center")
self.OptionParser.add_option("-c", "--pitchcircle",
action="store", type="inkbool",
dest="pitchcircle", default=False,
help="Draw pitch circle (for mating)")
self.OptionParser.add_option("-r", "--draw-rack",
action="store", type="inkbool",
dest="drawrack", default=False,
help="Draw rack gear instead of spur gear")
self.OptionParser.add_option("", "--rack-teeth-length",
action="store", type="int",
dest="teeth_length", default=12,
help="Length (in teeth) of rack")
self.OptionParser.add_option("", "--rack-base-height",
action="store", type="float",
dest="base_height", default=8,
help="Height of base of rack")
self.OptionParser.add_option("", "--rack-base-tab",
action="store", type="float",
dest="base_tab", default=14,
help="Length of tabs on ends of rack")
self.OptionParser.add_option("", "--undercut-alert",
action="store", type="inkbool",
dest="undercut_alert", default=False,
help="Let the user confirm a warning dialog if undercut occurs. This dialog also shows helpful hints against undercut")
[docs]
def calc_circular_pitch(self):
"""We use math based on circular pitch."""
dimension = self.options.dimension
if self.options.system == 'CP': # circular pitch
circular_pitch = dimension * 25.4
elif self.options.system == 'DP': # diametral pitch
circular_pitch = pi * 25.4 / dimension
elif self.options.system == 'MM': # module (metric)
circular_pitch = pi * dimension
else:
raise ValueError("unknown system '%s', try CP, DP, MM" % self.options.system)
# circular_pitch defines the size in mm
return circular_pitch
[docs]
def generate_spokes(self, root_radius, spoke_width, spokes, 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
"""
if not spokes:
return []
# Spokes
collision = False # assume we draw spokes
messages = [] # messages to send back about changes.
spoke_holes = []
r_outer = root_radius - spoke_width
try:
spoke_count = spokes
spokes = [i*2*pi/spokes for i in range(spoke_count)]
except TypeError:
spoke_count = len(spokes)
spokes = [radians(a) for a in spokes]
spokes.append(spokes[0]+two_pi)
# 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(f"Mount support too small. Auto increased to {mount_radius/unit_factor*2:2.2f}{unit_label}.")
# then check to see if cross-over on spoke width
for i in range(spoke_count):
angle = spokes[i]-spokes[i-1]
if spoke_width >= angle * mount_radius:
adj_factor = 1.2 # wrong value. its probably one of the points distances calculated below
mount_radius += adj_factor
messages.append(f"Too many spokes. Increased Mount support by {adj_factor/unit_factor:2.3f}{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):
self.boxes.ctx.save()
start_a, end_a = spokes[i], spokes[i+1]
# 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)
# 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
a2 = asin(asin_factor)
l = vlength(vdiff(point_on_circle(mount_radius, start_a + a),
point_on_circle(r_outer, start_a + a2)))
self.boxes.moveTo(*point_on_circle(mount_radius, start_a + a), degrees=degrees(start_a))
self.boxes.polyline(
l,
+90+degrees(a2), 0,
(degrees(end_a-start_a-2*a2), r_outer), 0,
+90+degrees(a2),
l, 90-degrees(a), 0,
(-degrees(end_a-start_a-2*a), mount_radius),
0, 90+degrees(a2), 0
)
self.boxes.ctx.restore()
return messages
[docs]
def sizes(self, **kw):
self.options = self.OptionParser.parse_args([f"--{name}={value}" for name, value in kw.items()])
# Pitch (circular pitch): Length of the arc from one tooth to the next)
# Pitch diameter: Diameter of pitch circle.
pitch = self.calc_circular_pitch()
if self.options.drawrack:
base_height = self.options.base_height * unit_factor
tab_width = self.options.base_tab * unit_factor
tooth_count = self.options.teeth_length
width = tooth_count * pitch + 2*tab_width
height = base_height+ 2* addendum
return 0, width, height
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
# 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)
if self.options.internal_ring:
outer_radius += self.options.spoke_width
return pitch_radius, 2*outer_radius, 2*outer_radius
[docs]
def gearCarrier(self, r, spoke_width, positions, mount_radius, mount_hole, circle=True, callback=None, move=None):
width = 2*r+spoke_width
if self.boxes.move(width, width, move, before=True):
return
try:
positions = [i*360/positions for i in range(positions)]
except TypeError:
pass
self.boxes.ctx.save()
self.boxes.moveTo(width/2.0, width/2.0)
if callback:
self.boxes.cc(callback, None)
self.generate_spokes(r+0.5*spoke_width, spoke_width, positions, mount_radius, mount_hole, 1, "")
self.boxes.hole(0, 0, mount_hole)
for angle in positions:
self.boxes.ctx.save()
self.boxes.moveTo(0, 0, angle)
self.boxes.hole(r, 0, mount_hole)
self.boxes.ctx.restore()
self.boxes.moveTo(r+0.5*spoke_width+self.boxes.burn, 0, 90)
self.boxes.corner(360, r+0.5*spoke_width)
self.boxes.ctx.restore()
self.boxes.move(width, width, move)
def __call__(self, teeth_only=False, move="", callback=None, **kw):
""" 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
"""
self.options = self.OptionParser.parse_args([f"--{name}={value}" for name, value in kw.items()])
warnings = [] # list of extra messages to be shown in annotations
# calculate unit factor for units defined in dialog.
unit_factor = 1
# 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)
b = self.boxes.burn
# Add Rack (instead)
if self.options.drawrack:
base_height = self.options.base_height * unit_factor
tab_width = self.options.base_tab * unit_factor
tooth_count = self.options.teeth_length
(points, guide_points) = generate_rack_points(tooth_count, pitch, addendum, angle,
base_height, tab_width, clearance, pitchcircle)
width = tooth_count * pitch + 2 * tab_width
height = base_height + 2 * addendum
if self.boxes.move(width, height, move, before=True):
return
self.boxes.cc(callback, None)
self.boxes.moveTo(width/2.0, base_height+addendum, -180)
if base_height < 0:
points = points[1:-1]
self.boxes.drawPoints(points, close=base_height >= 0)
self.boxes.drawPoints(guide_points, kerfdir=0)
self.boxes.move(width, height, move)
return
# Move only
width = height = 2 * outer_radius
if self.options.internal_ring:
width = height = width + 2 * self.options.spoke_width
if not teeth_only and self.boxes.move(width, height, move, before=True):
return
# 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"))
# All base calcs done. Start building gear
points = generate_spur_points(teeth, base_radius, pitch_radius, outer_radius, root_radius, accuracy_involute, accuracy_circular)
if not teeth_only:
self.boxes.moveTo(width/2, height/2)
self.boxes.cc(callback, None, 0, 0)
self.boxes.drawPoints(points)
# Spokes
if not teeth_only and not self.options.internal_ring: # only draw internals if spur gear
msg = self.generate_spokes(root_radius, spoke_width, spoke_count, mount_radius, mount_hole,
unit_factor, self.options.units)
warnings.extend(msg)
# Draw mount hole
# A : rx,ry x-axis-rotation, large-arch-flag, sweepflag x,y
r = mount_hole / 2
self.boxes.hole(0, 0, r)
elif not teeth_only:
# its a ring gear
# which only has an outer ring where width = spoke width
r = outer_radius + spoke_width + self.boxes.burn
self.boxes.ctx.save()
self.boxes.moveTo(r, 0)
self.boxes.ctx.arc(-r, 0, r, 0, 2*pi)
self.boxes.ctx.restore()
# Add center
if centercross:
cs = pitch / 3.0 # centercross length
self.boxes.ctx.save()
self.boxes.ctx.move_to(-cs, 0)
self.boxes.ctx.line_to(+cs, 0)
self.boxes.ctx.move_to(0, -cs)
self.boxes.ctx.line_to(0, +cs)
self.boxes.ctx.restore()
# Add pitch circle (for mating)
if pitchcircle:
self.boxes.hole(0, 0, pitch_radius)
# 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),
f'DP: {25.4 * pi / pitch:2.3f} Module: {pitch:2.4f}(mm)',
'Pressure Angle: %2.2f degrees' % (angle),
f'Pitch diameter: {pitch_radius * 2 / unit_factor:2.3f} {self.options.units}',
f'Outer diameter: {outer_dia / unit_factor:2.3f} {self.options.units}',
f'Base diameter: {base_radius * 2 / unit_factor:2.3f} {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.boxes.text(note, -outer_radius, y)
y += text_height * 1.2
if not teeth_only:
self.boxes.move(width, height, move)
