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Assign weight to a mocked up part

jon_smirljon_smirl Member Posts: 15 ✭✭✭✭
I'd like to get an estimate for the center of gravity of my design. The design includes multiple mock ups of purchased parts (like motor, speaker, etc). I'd like to enter a weight for the part. It is good enough for my purposes to assume uniform density of the part. I see we can pick materials for a part, but I see no way to simply enter a weight.

It is also too hard to search for a density in the material list that is close since the densities are in alphabetical order, not in order of density.
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Answers

  • brucebartlettbrucebartlett Member, OS Professional, Mentor, User Group Leader Posts: 2,120 PRO
    edited June 2016
    I had the same problem last week, I needed to add a weight to a component to work out centre of gravity of a loaded machine. I ended up searching the list to find a material with density close to the one I wanted to get the right mass of the component, it worked in this case but not an ideal solution.  

    It would be nice to be able to specify density's / make custom materials and add a known weight to be uniform across the part independent of density.  
    Engineer ı Product Designer ı Onshape Consulting Partner
    Twitter: @onshapetricks  & @babart1977   
  • Martin_SøndergaardMartin_Søndergaard Member Posts: 1 PRO
    I'm currently in a similar situation. Considering the age of the post, do we have an update on this subject?
  • tim_hess427tim_hess427 Member Posts: 648 PRO
    Its now possible to add your own custom material list:

    https://cad.onshape.com/help/Content/material_library.htm
  • bill_danielsbill_daniels Member Posts: 277 ✭✭✭
    Custom materials list doesn't cut it.  When I import a part, I need a way to enter its weight as part of the import process.
  • tim_hess427tim_hess427 Member Posts: 648 PRO
    @bill_daniels - Out of curiosity, why wouldn't assigning the right material with correct density to the part have the same effect in your use-case?
  • lemon1324lemon1324 Member, Developers Posts: 216 EDU
    I've definitely done this for a couple projects - import, measure the volume, then create a new material in my "Weight Estimation" material library with the density as calculated from the mass I want to assign and the volume of the part. Assign this to the part, and assuming it's a part of near-uniform density, you can do CoG analysis etc pretty well.
    Arul Suresh
    PhD, Mechanical Engineering, Stanford University
  • PrachiPrachi Member, OS Professional Posts: 262 PRO
    Try the "set material" feature script. Can be found with search under same name. You will need an object to select at the CofG.
    Very handy when working with imported files that have only surfaces or no material defined.
    You can set weight to catalog value as is needed.
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