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radzimir / fusion_worm_gear

Script for generating worm gear in Fusion 360 environment.
GNU General Public License v3.0
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Worm Revolution is Backwards #1

Open altbelly opened 2 years ago

altbelly commented 2 years ago

Amazing tool! Thank you for developing and sharing this!

I believe your "wormRotationAngle" variable is calculated incorrectly causing the worm to turn the wrong direction and carve the "wheel gear" incorrectly. I believe the issue is disguised when testing with 2 cuttingStepsProWormTurn because it's symmetrical for a rotation of 180* but the issue happens for values above 2.

Solution - I changed line 251 from:

wormRotationAngle = wormTurns 2math.pi / steps

to:

wormRotationAngle = -1 wormTurns 2*math.pi / steps

and now it appears to work correctly!

I used the parameters below to generate the two screenshots of the worm gear sets, one with the positive wormRotationAngle and one with the negative wormRotationAngle.

positive_worm_rotation negative_worm_rotation

    # START OF PARAMETERS SECTION YOU MAY/SHOUD ADJUST

    # Terminology by http://www.tandwiel.info/de/verzahnungen/nomenklatur-verzahnungen-tandwiel-info/

    # Multiply module by 0.1 to convert from mm into internal cm unit
    self.module = 0.1*1
    self.pressureAngle = fromGrad(0)
    self.wheelTeethNumber = 20 # must be even number
    self.wormRotations = 5
    self.wormAxisAngle = fromGrad(0)

    '''
    2  - for initial testing
    10 - OK
    15 - OK
    17 - probably some cut errors, result quality OK
    20 - probably somecut errors,  result quality perfect, long calculating time, many small faces
    '''
    self.cuttingStepsProWormTurn = 10 # minimal 2
altbelly commented 2 years ago

Wait, this is only an issue for a worm axis angle of 0. It appears that for other values of the worm axis angle that statement in line 251 SHOULD be positive.