how to assign a new weight (mass) to a component

[prefetch]

i'm working on a weight sensitive project that i'm importing different components into (motors, electronic units, etc.) from various online sources.

fusion 360 seems to do a pretty good job of accepting a variety of 3d file formats, which is great.

the problem is that more often than not, the calculated weight of the components are way off.

eg. i import an electric motor, check it's properties and the mass says 13.3 lbmass, but the data sheet from the vendor says it's 3.1 lbs.

what i'd like to do of course is just edit the properties and make it 3.1 lbs.

but it seems like fusion won't let me do that, so as a work around i change the physical material the component is made of to something lighter and guess and check and guess and check until it gets closer to reality.  of course, this is stupid, and i'd rather not do this.

so...any ideas?  how is this supposed to work?

[Anonymous]

I don't think there is a direct way to do this. You should add direct mass editing to the IdeaStation.

What I've done in the past is shell the motor housing to get the correct weight. It's still guess, check, guess, check..., but at least I end up with a somewhat representative physical material.

[prefetch]

wow. yeah, that's kind of bad.

i guess i can go post it in suggested features part of the forum, but i'm surprised that this isn't something other people have stumbled on over the last few years.

[nick.ni]

Mass is caculated based on the real model. I think it's a reasonable request to override it.

If you create drawing for the part, a workaround is to input Weight in the Title BLock. You can input any data in the Title BLock.

[Anonymous]

Someone else beat you to the punch. An idea for mass editing is posted here:

https://forums.autodesk.com/t5/ideastation-request-a-feature-or/apply-define-a-set-mass-to-a-body/id...

[martinmonras]

It´s a petty that a function like this doesn´t exist. But considering that it probably won´t exist for a while, your method of changing the density of the material will have to do for now, though it can be optimized.

You can go to properties and find out the volume of the object or component, and then do the math to work out the density you need to hit your target weight/mass. Once you got the target density, just define any material, and then edit the density of the material. You can do this by right clicking the material you’ve chosen, go to edit,        advanced, physical, and just set the density you want.

Hope this helps for now.

[Phil.E]

@martinmonras Exactly. It's pretty simple if you know the volume and target weight.

For reference:

[Noah_Katz]

Or just note the ratio of the the desired mass to the actual mass, and then multiply that times the material density.

[barry9UDQ6]

COG is something that I work with a lot, using a combination of modeled up geometry and imported components that have a given weight. i.e. outboard motors.

I bring the outboard model in as surfaces and then create a custom material with the correct density.

This can then be used to calculate COG's for my overall assembly.