Onshape Instructor Kit - 1.2.1 - Basic Sketching, answer off by 0.001

james_hawkins111

I have attached the sketch and the mass properties as images.  I am perplexed how the answer is so close, only off by one thousandth.  I believe I have all of the tangents, but I must have missed something.  Can anyone spot what I may be missing?

mthiesmeyer

Hi James,

I have attached an image that is fully constrained. Does the fix make sense? (the value of the dimension I added is probably wrong for your purposes)



Best,

Mike

NeilCooke

I think you're supposed to add a tangency constraint between these two:

ilya_baran

The blue color of the lines/arcs/points indicates that they are not fully constrained.

james_hawkins111

I applied the dimension suggested by MichaelThiesmeyer, and I (separately) added the tangency constraint suggested by NeilCooke, and in both cases the model became fully constrained; however, the final volume still only calculated as 0.701.

Here is a link to the document in case this helps at all:

https://cad.onshape.com/documents/7d1de9c30c97b792e9730f17/w/280c34663a4ccb798fa0a873/e/7a1af0ac882c848df42ee9a7

brian_brady

I found it. Your angled lines that contact the upper and lower Ø0.75 circles need to be tangent to those two circles. The end points of your lines are horizontally aligned to the centers of the circles, which are not the tangency points. Same issue with the two angled lines that should be tangent to the Ø0.625 circle.