PartDesign InvoluteGear/cs: Difference between revisions

From FreeCAD Documentation
(Updating to match new version of source page)
(Updating to match new version of source page)
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=== Create a spur gear ===
=== Create a spur gear ===


# Select the gear profile in the tree.
# Select the gear profile in the [[Tree_view|Tree view]].
# Press the {{Button|[[Image:PartDesign_Pad.svg|16px]] PartDesign Pad}} button.
# Press the {{Button|[[Image:PartDesign_Pad.svg|16px]] [[PartDesign_Pad|PartDesign Pad]]}} button.
# Set the pad's {{PropertyData|Length}} to the desired face width of the gear.
# Set the pad's {{PropertyData|Length}} to the desired face width of the gear.
# Click {{Button|OK}}
# Click {{Button|OK}}
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{{Version|0.19}}
{{Version|0.19}}


# Select the gear profile in the tree.
# Select the gear profile in the [[Tree_view|Tree view]].
# Press the {{Button|[[Image:PartDesign_AdditiveHelix.svg|16px]] [[PartDesign_AdditiveHelix|PartDesign AdditiveHelix]]}} button.
# Press the {{Button|[[Image:PartDesign_AdditiveHelix.svg|16px]] [[PartDesign_AdditiveHelix|PartDesign AdditiveHelix]]}} button.
# Choose as Axis the normal of the gear profile, that is {{MenuCommand|Normal sketch axis}} {{Version|0.20}}. (In earlier versions the {{MenuCommand|Base Z axis}} can be used as long as the profile's plane has not been altered.)
# Choose as Axis the normal of the gear profile, that is {{MenuCommand|Normal sketch axis}} {{Version|0.20}}. (In earlier versions the {{MenuCommand|Base Z axis}} can be used as long as the profile's plane has not been altered.)
# Choose a {{MenuCommand|Height-Turns}} mode.
# Choose a {{MenuCommand|Height-Turns}} mode.
# Set the {{PropertyData|Height}} to the desired face width of the gear.
# Set the {{PropertyData|Height}} to the desired face width of the gear.
# To set the desired helical angle an [[Expressions]] for the {{PropertyData|Turns}} is required.
# To set the desired helical angle an [[Expressions|Expression]] for the {{PropertyData|Turns}} is required.
## Click the blue [[Image:Bound-expression.svg|16px]] icon at the right of the input field.
## Click the blue [[Image:Bound-expression.svg|16px]] icon at the right of the input field.
## Enter the following formula: {{incode|Height * tan(25°) / (InvoluteGear.NumberOfTeeth * InvoluteGear.Modules * pi)}}, where {{incode|25°}} is an example for the desired helical angle (also known as beta-value) and {{incode|InvoluteGear}} is the {{PropertyData|Name}} of the profile.
## Enter the following formula: {{incode|Height * tan(25°) / (InvoluteGear.NumberOfTeeth * InvoluteGear.Modules * pi)}}, where {{incode|25°}} is an example for the desired helical angle (also known as beta-value) and {{incode|InvoluteGear}} is the {{PropertyData|Name}} of the profile.
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* {{PropertyData|Pressure Angle}}: Acute angle between the line of action and a normal to the line connecting the gear centers. Default is 20 degrees. ([https://en.wikipedia.org/wiki/Involute_gear More info])
* {{PropertyData|Pressure Angle}}: Acute angle between the line of action and a normal to the line connecting the gear centers. Default is 20 degrees. ([https://en.wikipedia.org/wiki/Involute_gear More info])


==Limitations==

* It is currently not possible to adjust the tooth thickness. Tooth and tooth space are distributed equally on the pitch circle. Thus the only way to control backlash is to adjust the center distance in a gear paring.
* There is currently no [https://www.tec-science.com/mechanical-power-transmission/involute-gear/undercut/ undercut] in the generated gear profile. That means gears with a low number of teeth can interfere with the teeth of the mating gear. The lower limit depends on the {{PropertyData|Pressure Angle}} and is around 17 teeth for 20° and 32 for 14.5°. Most practical applications tolerate a missing undercut for gears a little smaller than this theoretical limit though.


==Tutorials==
==Tutorials==

Revision as of 20:04, 27 January 2022

PartDesign InvoluteGear

Umístění Menu
Part Design → Involute gear...
Pracovní stoly
PartDesign
Výchozí zástupce
Nikdo
Představen ve verzi
-
Viz také
Nikdo

Description

This tool allows you to create a 2D profile of an involute gear. This 2D profile is fully parametric, and can be padded with the PartDesign Pad or PartDesign AdditiveHelix feature.

For more detailed information see Wikipedia's entries for: Gear and Involute Gear

Usage

Create the profile

  1. Optionally activate the correct body.
  2. Go to the menu Part Design → Involute gear....
  3. Set the Involute parameters.
  4. Click OK.
  5. If there was no active body: drag and drop the gear into a body for the application of further features like padding.

Create a spur gear

  1. Select the gear profile in the Tree view.
  2. Press the PartDesign Pad button.
  3. Set the pad's ÚdajeLength to the desired face width of the gear.
  4. Click OK

Create a helical gear

introduced in version 0.19

  1. Select the gear profile in the Tree view.
  2. Press the PartDesign AdditiveHelix button.
  3. Choose as Axis the normal of the gear profile, that is Normal sketch axis introduced in version 0.20. (In earlier versions the Base Z axis can be used as long as the profile's plane has not been altered.)
  4. Choose a Height-Turns mode.
  5. Set the ÚdajeHeight to the desired face width of the gear.
  6. To set the desired helical angle an Expression for the ÚdajeTurns is required.
    1. Click the blue icon at the right of the input field.
    2. Enter the following formula: Height * tan(25°) / (InvoluteGear.NumberOfTeeth * InvoluteGear.Modules * pi), where 25° is an example for the desired helical angle (also known as beta-value) and InvoluteGear is the ÚdajeName of the profile.
    3. Click OK to close the formula editor.
  7. Click OK to close the task panel.

Hint: To make the helical angle an accessible parameter, use a dynamic property:

  1. Select the profile.
  2. In the Property editor activate the Show all option in the context menu.
  3. Again in the context menu, select Add Property. Note: this entry is only available when Show all is active.
  4. In the Add Property dialog:
    1. Choose App::PropertyAngle as Type.
    2. Set Gear as Group.
    3. Set HelicalAngle as Name (without a space).
    4. Click OK
  5. Now a new property ÚdajeHelical Angle (space added automatically), with an initial value of 0.0°, becomes available.
  6. Assign the desired helical angle to the new property.
  7. In the formula of the ÚdajeTurns property of the AdditiveHelix, you can now reference InvoluteGear.HelicalAngle instead of the hard coded value of e.g. 25°; again assuming InvoluteGear is the ÚdajeName of the profile.

Properties

  • ÚdajeExternal Gear: True or false
  • ÚdajeHigh Precision: True or false
  • ÚdajeModules: Pitch diameter divided by the number of teeth.
  • ÚdajeNumber Of Teeth: Sets the number of teeth.
  • ÚdajePressure Angle: Acute angle between the line of action and a normal to the line connecting the gear centers. Default is 20 degrees. (More info)


Limitations

  • It is currently not possible to adjust the tooth thickness. Tooth and tooth space are distributed equally on the pitch circle. Thus the only way to control backlash is to adjust the center distance in a gear paring.
  • There is currently no undercut in the generated gear profile. That means gears with a low number of teeth can interfere with the teeth of the mating gear. The lower limit depends on the ÚdajePressure Angle and is around 17 teeth for 20° and 32 for 14.5°. Most practical applications tolerate a missing undercut for gears a little smaller than this theoretical limit though.

Tutorials

How to make gears in FreeCAD

Related