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Gear Lab - Cylindrical, Bevel, Face Gears
antlu65
Member Posts: 55 EDU
Yup, it's another custom feature for gears. I had previously used Neil Cooke's excellent 'Spur Gear' feature [Link], but I wanted the ability to generate bevel and face gears as well. I only learned about Bob Tipton's great bevel gear FS after I had nearly finished this. I fear that my "Gear Lab" custom feature is largely rehashing what has already been done, but I thought I'd share what I have in case anyone does find a use for it.
Here is a brief description of the feature set:
Here is a brief description of the feature set:
--- Gear Lab ---
* Generate cylindrical gears (spur, helical, herringbone, internal) with involute teeth.
* Generate bevel gears (straight, spiral, herringbone, internal) with spherical involute teeth.
* Generate face gears (straight, spiral, herringbone) with trapezoidal teeth and varying pressure angle.
* Position generated gear by specifying primitive geometry (a face, a face and vertex, an edge and vertex, etc.)
* Generate and position a gear by selecting a 'parent' gear created by this custom feature. The 'child' gear will have parameters and positioning set to fit the parent gear. Can enter an angle offset, or align to other geometry primitives.
* Generate and position a gear by selecting a 'parent' gear created by this custom feature. The 'child' gear will have parameters and positioning set to fit the parent gear. Can enter an angle offset, or align to other geometry primitives.
* Adjustment settings: bore + keyway, tooth chamfer, root fillet, tip/root/side adjustments, minimum land.
A few additional comments:
- most inputs are unitless and represent multiples of the gear module; consequently, changing the module will scale the entire part (with a few minor exceptions like the bore/keyway options).
- the pressure angle input is specifically for *normal* pressure angle (I believe the 'Spur Gear' feature uses transverse pressure angle for its input).
- the type of gear is determined by the bevel angle 𝛿 (𝛿 = 0 for cylindrical gear, 𝛿 = 90 for face gear); the face gear produced here is for meshing with cylindrical gears; the code can handle creating a face gear for meshing with bevel gears (𝛿 = 90 with spherical involute teeth), but I wasn't sure how to elegantly present that option to the user, so I left it out.
- the helical/spiral teeth are right-handed for positive values, and left-handed for negative values; the spiral bevel and face gear teeth follow a logarithmic spiral; could implement additional spiral patterns if requested, or zerol teeth.
- when using the "Inherit from Parent Gear" mode, valid unselected parent gears are highlighted in cyan; the currently selected parent gear is not highlighted.
- when specifying a Shaft Angle for a bevel gear pair, the resulting shaft angle may be slightly different from your input - this is because gear teeth are restricted to integer values. But for common usage where both bevel gears have the same bevel angle, this won't be an issue.
- the "minimum land" input in the Advanced Settings enforces a minimum tooth tip width (top land) to prevent teeth narrowing to a sharp point at high pressure angle.
- most inputs are unitless and represent multiples of the gear module; consequently, changing the module will scale the entire part (with a few minor exceptions like the bore/keyway options).
- the pressure angle input is specifically for *normal* pressure angle (I believe the 'Spur Gear' feature uses transverse pressure angle for its input).
- the type of gear is determined by the bevel angle 𝛿 (𝛿 = 0 for cylindrical gear, 𝛿 = 90 for face gear); the face gear produced here is for meshing with cylindrical gears; the code can handle creating a face gear for meshing with bevel gears (𝛿 = 90 with spherical involute teeth), but I wasn't sure how to elegantly present that option to the user, so I left it out.
- the helical/spiral teeth are right-handed for positive values, and left-handed for negative values; the spiral bevel and face gear teeth follow a logarithmic spiral; could implement additional spiral patterns if requested, or zerol teeth.
- when using the "Inherit from Parent Gear" mode, valid unselected parent gears are highlighted in cyan; the currently selected parent gear is not highlighted.
- when specifying a Shaft Angle for a bevel gear pair, the resulting shaft angle may be slightly different from your input - this is because gear teeth are restricted to integer values. But for common usage where both bevel gears have the same bevel angle, this won't be an issue.
- the "minimum land" input in the Advanced Settings enforces a minimum tooth tip width (top land) to prevent teeth narrowing to a sharp point at high pressure angle.
I've attached several animated gifs below to briefly demonstrate some of the features. Please let me know if you find it useful, have suggestions, feature requests, bugs, etc.
Gear Lab [Link]:
Gear Lab [Link]:
Tagged:
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Comments
IDK if it's something up with my onshape account, but I can't seem to add it to my toolbar
* Performance improvements. Patterning the gear teeth using face patterns (instead of patterning bodies and using union) has significantly improved feature regen time. Unfortunately, there is currently an issue applying face patterns to root fillets. I have submitted a support ticket with Onshape Support to hopefully have this addressed.
Just wanted to say I've been testing this feature out on a side project and I really love it! really good work. If you're interested, I could put together a short list of ideas for improvements that have come to me while using it.
Website: ovyl.io
The behavior of helix angle when working with bevel gears is incorrect.
This is a tremendous tool, thank you so much for your work. I noticed that the root fillet does not seem to work when using bevel gears, so I wanted to bring this to your attention, @antlu65. Once again, thank you for your impressive contribution.
I have just played with Gear Lab, works nice!
Question, why is the bore size limited to 20mm?
How can I get the circle in line with the teeth?
Otherwise you need to create a second "gear" feature and use the "inherit from parent gear" option at the top to create a compatible gear.
But then realized that it's the bevel angle that is going to set the ratio: 45 deg requires two identical gears, try setting the parent gear to something else (like 30deg) and you will see the number of teeth adjust accordingly (an error message would be helpful here).
A good tip is that you can edit the first gear feature with the "final" button enabled to see how the changes to the first one affects the second.
That said I'm really not an expert on gears so you might want to do some reading on how all of this works if you want to get predictable results. I'm sure there's a formula you can use to figure out the exact bevel angle for the ratio you want (rather than trial and error) but I don't know it off the top of my head.
Cheers