Planetary2: New generator for a ~100 reduction to belt pulley
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Florian Festi
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93480e082d
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8487d5c379
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#!/usr/bin/env python3
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# Copyright (C) 2013-2016 Florian Festi
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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from boxes import *
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import math
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class Planetary2(Boxes):
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"""Balanced force Difference Planetary Gear"""
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ui_group = "Part"
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def __init__(self):
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Boxes.__init__(self)
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self.buildArgParser("nema_mount")
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self.argparser.add_argument(
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"--profile", action="store", type=str, default="GT2_2mm",
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choices=pulley.Pulley.getProfiles(),
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help="profile of the teeth/belt")
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self.argparser.add_argument(
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"--sunteeth", action="store", type=int, default=8,
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help="number of teeth on sun gear")
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self.argparser.add_argument(
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"--planetteeth", action="store", type=int, default=20,
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help="number of teeth on planets")
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self.argparser.add_argument(
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"--maxplanets", action="store", type=int, default=0,
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help="limit the number of planets (0 for as much as fit)")
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self.argparser.add_argument(
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"--deltateeth", action="store", type=int, default=1,
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help="enable secondary ring with given delta to the ring gear")
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self.argparser.add_argument(
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"--modulus", action="store", type=float, default=3,
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help="modulus of the theeth in mm")
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self.argparser.add_argument(
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"--shaft", action="store", type=float, default=6.,
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help="diameter of the shaft")
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self.argparser.add_argument(
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"--screw1", action="store", type=float, default=2.4,
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help="diameter of lower part of the screw hole")
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self.argparser.add_argument(
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"--screw2", action="store", type=float, default=4.,
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help="diameter of upper part of the screw hole")
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self.argparser.add_argument(
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"--pinsize", action="store", type=float, default=3.1,
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help="diameter of alignment pins")
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# self.argparser.add_argument(
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# "--stages", action="store", type=int, default=4,
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# help="number of stages in the gear reduction")
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def pins(self, r, rh, nr=0, angle=0.0):
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self.moveTo(0, 0, angle)
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if nr < 8:
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ang = 20 + 10 * nr
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else:
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ang = 15 + 10 * (nr-8)
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ang = 180 - ang
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for a in (0, ang, -ang):
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self.moveTo(0, 0, a)
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self.hole(r, 0, rh)
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self.moveTo(0, 0, -a)
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def render(self):
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# Initialize canvas
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self.open()
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ringteeth = self.sunteeth + 2 * self.planetteeth
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t = self.thickness
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spoke_width = 4 * t
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pinsize = self.pinsize / 2.
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pitch1, size1, xxx = self.gears.sizes(teeth=self.sunteeth,
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dimension=self.modulus)
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pitch2, size2, xxx = self.gears.sizes(teeth=self.planetteeth,
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dimension=self.modulus)
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pitch3, size3, xxx = self.gears.sizes(
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teeth=ringteeth, internal_ring=True, spoke_width=spoke_width,
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dimension=self.modulus)
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planets = int(math.pi / (math.asin(float(self.planetteeth + 2) / (self.planetteeth + self.sunteeth))))
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if self.maxplanets:
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planets = min(self.maxplanets, planets)
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# Make sure the teeth mash
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ta = self.sunteeth + ringteeth
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# There are sunteeth+ringteeth mashing positions for the planets
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planetpositions = [round(i * ta / planets) * 360 / ta for i in range(planets)]
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secondary_offsets = [((pos % (360. / (ringteeth - self.deltateeth))) -
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(pos % (360. / ringteeth)) * ringteeth / self.planetteeth)
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for pos in planetpositions]
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ratio = (1 + (ringteeth / self.sunteeth)) * (-ringteeth/self.deltateeth)
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print(planetpositions)
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print(secondary_offsets)
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print(ratio)
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# XXX make configurable?
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profile_shift = 20
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pressure_angle = 20
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screw = self.screw1 / 2
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# output
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# XXX simple guess
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belt = self.profile
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pulleyteeth = int((size3-2*t) * math.pi / pulley.Pulley.spacing[belt][1])
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numplanets = planets
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deltamodulus = self.modulus * ringteeth / (ringteeth - self.deltateeth)
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def holes(r):
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def h():
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self.hole(2*t, 2*t, r)
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self.hole(size3-2*t, 2*t, r)
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self.hole(2*t, size3-2*t, r)
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self.hole(size3-2*t, size3-2*t, r)
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return h
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def planets():
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self.moveTo(size3/2, size3/2)
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for angle in planetpositions:
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angle += 180 # compensate for 3 postion in callback
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self.moveTo(0, 0, angle)
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self.hole((pitch1+pitch2), 0, size2/2)
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self.moveTo(0, 0, -angle)
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self.rectangularWall(size3, size3, callback=[
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lambda: self.NEMA(self.nema_mount, size3 / 2, size3 / 2),
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holes(screw), planets],
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move="up")
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def gear():
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self.moveTo(size3 / 2, size3 / 2)
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self.gears(teeth=ringteeth, dimension=self.modulus,
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angle=pressure_angle, internal_ring=True,
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spoke_width=spoke_width, teeth_only=True,
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profile_shift=profile_shift, move="up")
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self.rectangularWall(size3, size3, callback=[gear, holes(screw)], move="up")
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screw = self.screw2 / 2
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self.rectangularWall(size3, size3, callback=[gear, holes(screw)], move="up")
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self.rectangularWall(size3, size3, callback=[holes(screw)], move="up")
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self.partsMatrix(4, 4, 'up', self.gears, teeth=self.sunteeth,
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dimension=self.modulus,
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angle=pressure_angle, mount_hole=self.shaft,
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profile_shift=profile_shift)
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tl = 0.5*size3*(2**0.5-1)*2**0.5
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self.rectangularTriangle(tl, tl, num=8, callback=[
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None, lambda:self.hole(2*t, 2*t, screw)], move='up')
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self.pulley(pulleyteeth, belt, callback=
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lambda:self.gears(teeth=ringteeth - self.deltateeth,
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dimension=deltamodulus,
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angle=pressure_angle, internal_ring=True,
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spoke_width=spoke_width, teeth_only=True,
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profile_shift=profile_shift), move="up")
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for i in range(numplanets):
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self.ctx.save()
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for j in range(2):
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self.gears(teeth=self.planetteeth, dimension=self.modulus,
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angle=pressure_angle,
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callback=lambda:self.pins(0.25*size2, pinsize, i),
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profile_shift=profile_shift, move="right")
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for j in range(2):
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self.gears(teeth=self.planetteeth, dimension=self.modulus,
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angle=pressure_angle,
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callback=lambda:self.pins(0.25*size2, pinsize, i,
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secondary_offsets[i]),
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profile_shift=profile_shift, move="right")
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self.ctx.restore()
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self.gears(teeth=self.planetteeth, dimension=self.modulus,
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angle=pressure_angle,
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profile_shift=profile_shift, move="up only")
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self.close()
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def main():
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b = Planetary()
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b.parseArgs()
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b.render()
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if __name__ == '__main__':
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main()
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