ฝัง
- เผยแพร่เมื่อ 17 ก.ย. 2024
- This video shows why choosing the most functional datum features benefits design, manufacturing, and inspection. Non-functional datum features cause stack ups of profile and position tolerance.
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This video should be the first lesson in any mechanical design class!
Great content, thanks for the refresher!
Great video man. Glad you're explicit about function in most of your videos. Want you to know that your explanations in my opinion are probably the best on youtube on this topic
Great content, keep it up!
Greate video!
For a designer a datum is a tool to simulate the contact of a part against a second part, which is not known with a single part drawing.
I‘m afraid:
- The function requires datums equal B and C: A|B-C
- The function of the slot is a fit against a different type of feature. The second part will offer a cylinder for this contact
- Under ISO GPS there is a big problem with such a datum system „A|B|C“. With „A|B“ only one DOF left. The third „C“ gives only a gradient. Typical the centerplane „C“ is to small to get a good result. I don‘t know these details under ASME (which are not „details“)
- A screwed main contact at datum A will cause functional relevant deformations? The part is not stiff against torsion…
Good comment. ISO-GPS has a different rule set for this geometry (axis as B and center plane as C). It forces the associated geometry to translate (distance is variable) to make full contact with the slot and stop rotation. Therefore, the short center plane is problematic because it does not constrain rotation well. Y14.5 is different. The true geometric counterpart (named associated geometry in ISO) remains fixed in location while constraining [7.5.2]. This allows the distance between the axis and center plane to also be leveraged to stop rotation. I think you're right, the work-around in ISO-GPS would be A/B-C for this one.
The 3 datum targets of the first datum, resulting in the 3 points forming a surface at an angle to the coordinate plane.
Question: Is there any negative effect of if the first datum plane is not being parallel to the coordinate axis at too large an angle?
I do not fully understand your question. Are you referring to the manufacturing set-up of 3 target points? And relative to which coordinate axis?
By the way, explain how to use PC-DMIS to detect geometric tolerances.
Do you mean by using PMI/MBD or what do you mean?
@@jorgenandersson6994 yes, MBD.
@@user-vl8dy1os6r th-cam.com/video/lknGBIfcstg/w-d-xo.html
Your CAD model MUST have MBD/PMI in it, otherwise it will not work.
@@jorgenandersson6994 I use Solidworks to add MBD to the model. What's your facebook?
I don't really go into the details of particular inspection software. But PC-DMIS is awesome for leveraging the PMI (GD&T annotations) applied to the CAD model.
why you get a big view but few comments?