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Placing mate connectors according to geometry grips
john_harkness106
Member Posts: 2 ✭
I'm still on Onshape learning curve. Practicing by creating a tubular frame. The image shows a view where two different tubes were mated to the face of tubes mitered together. I placed mate connectors according to the "grips" that appeared on geometry for tube ends and faces. What I've found is the tube mated at the miter is centered, but the other mated is off by a small amount. What's going on here? Thanks in advance.
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bradley_sauln
Moderator, Onshape Employees, Developers Posts: 373 
Ok, so the issue is that the assumed, centrally mated tubes are in perfect alignment. The problem is, if you look at my measurement there is an offset of DY 0.025 when that value should read DY 0.000. The fastened mate used for the beam on the right is using the centroid implicit mate connector (as stated in our help index on how mate connectors work) for the mitered beam seen. The centroid of a trapezoid is actually lower than the rectangle that encompasses (reference: http://formulas.tutorvista.com/math/centroid-of-a-trapezoid-formula.html) as seen in the image below. This results in the two verticle tubes not being perfectly aligned.
The solution to this is to add an explicit mate connector in the Part Studio that either references a sketch entity or face prior to the mitered corner so that you know it is in alignment with the midpoint of the height of the body. This ensures that your assembly is accurate and this mate connector will update to reflect changes in your design as well.
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HWM-Water Ltd
Ok, so the issue is that the assumed, centrally mated tubes are in perfect alignment. The problem is, if you look at my measurement there is an offset of DY 0.025 when that value should read DY 0.000. The fastened mate used for the beam on the right is using the centroid implicit mate connector (as stated in our help index on how mate connectors work) for the mitered beam seen. The centroid of a trapezoid is actually lower than the rectangle that encompasses (reference: http://formulas.tutorvista.com/math/centroid-of-a-trapezoid-formula.html) as seen in the image below. This results in the two verticle tubes not being perfectly aligned.
The solution to this is to add an explicit mate connector in the Part Studio that either references a sketch entity or face prior to the mitered corner so that you know it is in alignment with the midpoint of the height of the body. This ensures that your assembly is accurate and this mate connector will update to reflect changes in your design as well.
Twitter: @bradleysauln