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Thread profile modelling accuracy improvements (Feature Request) #9

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opened 2024-08-10 16:41:15 +02:00 by sw-tya · 0 comments
sw-tya commented 2024-08-10 16:41:15 +02:00
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The existing thread modelling is built around a trapezoidal construction. There are four input numbers used Inner and outer diameter plus the root and crest percentage.
This is good for specifying an ACME thread, but makes the input numbers for Metric (e.g. DIN 934) or Imperial (e.g. ASME b18.2.2) hard as the crest and root have tolerance where the angle of the thread does not. Information on Wikipedia is simplistic in the determination of parameters, both the inner and outer have the same dimensions. There are other thread standards that have different angles, determination of the correct input values is none trivial for most users.

Another major drawback with the current implementation is all thread building assumes an integer number of complete rotations. This causes the length to vary after the input. The rank is also fixed.

Not all threads have the same root/crest profile, some are rounded like: BA.

This ticket is first to acknowledge the short comings and then plan a route forward. An outcome might be that approximate/visual is the target and that documentation will be updated in respect of this to set a suitable expectation. This has become more important in recent years with the accessibility of 3D printing.

The existing thread modelling is built around a trapezoidal construction. There are four input numbers used Inner and outer diameter plus the root and crest percentage. This is good for specifying an ACME thread, but makes the input numbers for Metric (e.g. DIN 934) or Imperial (e.g. ASME b18.2.2) hard as the crest and root have tolerance where the angle of the thread does not. Information on Wikipedia is simplistic in the determination of parameters, both the inner and outer have the same dimensions. There are other thread standards that have different angles, determination of the correct input values is none trivial for most users. Another major drawback with the current implementation is all thread building assumes an integer number of complete rotations. This causes the length to vary after the input. The rank is also fixed. Not all threads have the same root/crest profile, some are rounded like: BA. This ticket is first to acknowledge the short comings and then plan a route forward. An outcome might be that approximate/visual is the target and that documentation will be updated in respect of this to set a suitable expectation. This has become more important in recent years with the accessibility of 3D printing.
sw-tya changed title from Thread modelling accuracy improvements (Feature Request) to Thread profile modelling accuracy improvements (Feature Request) 2024-08-10 20:39:50 +02:00
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Reference: extensions/add_mesh_BoltFactory#9
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