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Spur Gear Interference
Lansteys
Member Posts: 6 ✭✭
Hi,
Has anyone else had the issue, when creating a gear train, were teeth will interfere for a few degrees at the start and end of meshing? It is clearly noticeable on internal spur gears, and more so with a higher tooth count / smaller gear.
It can be observed within the sample file for spur gears and seems to be an issue with the geometry itself.
I have had a look at the script, but that much code is a bit beyond me.
Does anyone have anything to share regarding this, whether it is a fix or just a better diagnosis of the problem?
Thanks in advance!
Has anyone else had the issue, when creating a gear train, were teeth will interfere for a few degrees at the start and end of meshing? It is clearly noticeable on internal spur gears, and more so with a higher tooth count / smaller gear.
It can be observed within the sample file for spur gears and seems to be an issue with the geometry itself.
I have had a look at the script, but that much code is a bit beyond me.
Does anyone have anything to share regarding this, whether it is a fix or just a better diagnosis of the problem?
Thanks in advance!
0
Best Answers
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kevin_o_toole_1
Onshape Employees, Developers, HDM Posts: 565 
It looks to me like this is an issue with the displayed graphics, but not the underlying geometry.
When viewing CAD models, Onshape displays a triangle mesh approximation of the actual geometry, and it appears like the internal spur gear in the example has a somewhat low-resolution mesh. This makes it appear like the gears slightly interfere, but in reality the profiles are calculated so that they don't.
5 -
Lansteys
Member Posts: 6 ✭✭
Thanks for you answer!
I thought that this was a possibility, though it is hard to verify and givin that the tip of the gear interferes, which I assumed to be correctly represented in the model, I had discounted this as a possibility.
I did however notice that by tuning the number of teeth the interfearance can be removed. It seems less teeth work best.
I 3D printed a set of planetary gears created with the spur gear feature using 0.5mm clearance, which I achieved by offsetting the pitch circle diameter. On my printer this is a bit tight, but the teeth shape works as it should.
0
Answers
When viewing CAD models, Onshape displays a triangle mesh approximation of the actual geometry, and it appears like the internal spur gear in the example has a somewhat low-resolution mesh. This makes it appear like the gears slightly interfere, but in reality the profiles are calculated so that they don't.
I thought that this was a possibility, though it is hard to verify and givin that the tip of the gear interferes, which I assumed to be correctly represented in the model, I had discounted this as a possibility.
I did however notice that by tuning the number of teeth the interfearance can be removed. It seems less teeth work best.
I 3D printed a set of planetary gears created with the spur gear feature using 0.5mm clearance, which I achieved by offsetting the pitch circle diameter. On my printer this is a bit tight, but the teeth shape works as it should.