ouncemass sillyness

[mrm1018]

Mass of my part is in ouncemass regardless of whether I select (in, lbmass, psi) or (ft, lbmass, psi).

This is basic stuff guys, what gives?

[tyler_henderson]

Hi mrm,

It looks like you might be changing the Material Display Units in Preferences.  That controls how units are displayed in the Material dialogs, but does not control the units displayed for the Model properties.  If you want to see the Mass in "lbmass" you can use the "Units" control in the Model browser and change the units to "ft".  This will change the Model properties to display "lbmass".

Understood this may not be intuitive and we are working on a more unified and intuitive solution to controlling units.

Best regards,

[mrm1018]

Tyler,

Thank you for your response...yes, I figured changing the units would be more a software global setting as opposed to an individual model setting.

...and you're right, changing the length unit to feet to get the weight of a model in lbmass is the opposite of intuitive.

Hope you get it worked out soon, Fusion has a lot of potential.  I'll tell you though, I'm a little surprised at some of the things that have obviously had a lot of polish, and then I find stuff like this.  Just seems disproportionate.

Good luck!

-Mike

[tyler_henderson]

Thanks for the support, Mike.

Maybe you could help us out by answering a few questions:

1. Fusion has several workspaces that facilitate different workflows such as Modeling, Simulation, CAM, etc.  Is it important to use different sets of units in these workspaces? (e.g. centimeters in Modeling and millimeters in CAM).
2. If you would like to use different unit sets in the different workspaces, would you want to be able to choose different default unit sets for each workspace, or would it be better to have one set of defaults (Preferences) for all workspaces, then be able to edit the unit set for each workspace on-the-fly?
3. What about the units used in the Physical Materials UI?  Would you want that to be a unique default unit set, or would you want the materials to follow the Modeling units?
4. Same question for Drawing units.

Thanks again for being a Fusion customer.  We appreciate your feedback.

[mrm1018]

Tyler,

I'd be glad to help...

Let me tell you, not to brag, but to give you a sense of my CAD background...

I started using CAD in '92~'93 (man I'm old), it was ACAD R10...I was hooked!  Around '93~'94 I began using R12 with the AME package, and then sometime after that, I used the "Designer" add-on.  "Designer" introduced parametric modeling to me, which blew my freak'n mind to be honest.  Shortly thereafter I took a job using ComputerVision Personal Designer, now that was a terrible experience...but then they moved to Pro-E, which was amazing for it's time but too expensive for most folks to take seriously.  I tinkered with some Autodesk Mechanical Desktop at that time as well, and even was given some inside knowledge from Autodesk about this new fangled software they were working on, which would eventually become Inventor.  Without a doubt, I was an Autodesk fanboy, but then I was turned on to Solidworks, this would have been around '97~'98, and I never looked back.

I use Solidworks for my day job as an engineer, and have been for 12 years-ish.  I was turned on to Fusion 360 for some personal projects after I thought it would be a good idea for me to put a CNC milling machine in my garage!  Fusion 360's CAM capabilities are ABSOLUTELY incredible!

Anyway, that was probably way too much.  To your questions...

In general, units should be as easy to manipulate as possible in my opinion.  Even the well established Solidworks has units buried too deep as far as I'm concerned.  I think users should be able to switch and mix match English and Metric units in as easy and unconstrained manner as possible....of course making them easy to set to some sort of standard too for those that don't care to change them often.

But specifically, my replies would be:

1. See above, but I think if someone is designing in inches, they'll probably be machining in inches too.  I'm sure this isn't always the case, so making them easy to change, and making it obvious which units are being applied to values in a way that isn't obnoxious would be the goal.

2. Yes I think to all of that, being able to pick from predefined unit standards, then modifying them for personal preference, then saving them would be awesome!  The user must absolutely be able to change an individual length unit without being forced to have a specific mass unit too.

3.  Physical units of the material library should probably follow a standard for just English and Metric units.  Solidworks does a nice job of this in my opinion, and something you should look at if you haven't already.

4.  I think the answers to my previous questions would tell you where I'm at on drawings.

Please don't hesitate to hit me up for any other feedback, I'd love to help given how open you all have made Fusion for hobbyists.

-Mike

[tyler_henderson]

Thanks, Mike, this is helpful.  I'll definitely take a look at how SolidWorks handles their Material units.

One last question: Have you used Simulation in Fusion and if so, do you like the way Loads and Constraints dialog allow you to change the units per command instance?

[mrm1018]

Tyler, I've not ventured into the simulation side of things, so I can't say for sure, but given your description...yeah, I think I like it.

Also, maybe this is a stupid question...why lbm in lieu of lbf?  Maybe I'm wrong about this, but I'm pretty sure most other CAD/CAE package use lb (lbf) units.  Obviously I know the difference between pound mass and pound force, but most of us think of the objects we model in terms of their weight, not mass.  Most of us are considering the models we build as used on the planet earth, so gravity is pretty much constant here for all practical purposes. 😉

-Mike

[Anonymous]

I'd like to second Mike's point about being able to change mass units independent of the length units. Most of the work I do is with steel or aluminum, so it's very easy to get into pounds of material while still at small enough lengths that it's impractical to use feet. Even on larger scale items like work platforms, I'm taking measurements with a tape measure, so it's much easier to model in inches vs. decimal feet. But then I end up with a platform that's 4348 ounces, which has no intuitive meaning to me. Can 2 guys move that platform or do they need to get a forklift? I don't know, so I have to convert it to pounds, which is an extra step that could be removed with 1 global setting to show mass in pounds.

[tyler_henderson]

Hi Mike,

Yes, you have a good point about the syntax we use for our model properties.  However, I believe it is important for Fusion to use "lbmass" for actual mass values because we have integrated Simulation capabilities.  Simulation allows you to modify the acceleration of gravity, and you can also apply linear accelerations and angular velocities which can greatly change the forces in relation to the involved masses.  So we must distinguish mass (lbmass) from force (lbforce) in the Simulation workspace.  Doing so in the model workspace just keeps things consistent.

[mrm1018]

Tyler,

In certain types of simulation, lbmass would absolutely be important...  However, for stress/strain, it absolutely would not be important...force and pressure is of interest.

Regardless, in the model space, just examining the properties of a part, lbf would be the more appropriate unit.  Humans understand what weight is because we pick things up, weight is intuitive.  Mass, or how much total stuff, is not intuitive.

I understand Fusion is in an integrated environment, and maybe that makes it tough to sort all of this out...but it seems this might be making some things awkward with regard to the reality of how people work/think.

[tyler_henderson]

Understood.  But I think what you are trying to say is, rather than reporting the mass of the model, we should be reporting the weight of the model in the model properties.  Is that correct?  Or maybe we should report both mass and weight.  But if we did that the values would be identical in the Model space and it would feel redundant 🙂  This is certainly something we will consider.

BTW, I created an IdeaStation post about more flexibility in specifying units:

https://forums.autodesk.com/t5/ideastation-request-a-feature-or/more-flexibility-in-controlling-unit...

It would be great for you guys to vote for it and add and additional requirements there.

Thanks,

[mrm1018]

Yes Tyler...that's my opinion on the matter, I realize others may differ though.  I also see no need to list both mass and weight since they will have the same value here on mother earth. 😄

The more I think about it, I'm mostly bothered by the unit "lbmass" or "ouncemass" to be honest.  Maybe a little OCD coming out of me? 😉

If you really decided you want to list the part as it's mass then I think it would be less awkward as something like:

Mass: 12.345 lb

[John_Holtz]

Please keep one thing in mind: the English system is not universal. In the metric system, a unit of mass is the not the same numerical value as the unit of weight, so you cannot assume that mass and weight will have the same value. (And there are some that consider the true unit for mass in the English system is slugs, and its value is not numerically equal to the weight either.)

So, should the dialog show mass or weight? Or both? Can someone from Europe tell us how much they weigh? They probably have no idea because they actually measure their mass in kilograms. The metric system unit for weight is Newtons. The best "compromise" may be to report both mass and weight so that the user can display "500 g" and "1.1 lbf" if they want to (and assume that they are at a 1 Earth gravity .)

And then there are cultures that report pressure and stress in units of kg/mm^2. But I am straying off topic a bit.

[mrm1018]

John, all the more reason to change the system you have put in place. 🙂

-Mike

[beananimal]

And all this time has passed and no change to this silly convention...

I want to see the volume and mass of my components in usable units - where I can choose the formats for length and mass separately... for goodness sake, is that too hard to understand?

Instead I get numbers like 3.635E+04in^3. -  Humans don't interpret numbers like that naturally.

Why ohh why do you folks try to be so esoteric when tried and tested systems have worked so well for so long. Almost every other offering in this and related spaces give the user dimension and unit display options that can mixed and matched.  

Why can't I mix and match units in mass and length - it is hard math for the brain on the fly, but trivial for software... and here we are, having to click and switch the drawing units back forth or get out a calculator to figure things out.  

Recurring theme here... the more I dig into this software, the less comfortable and more frustrated I become, and it is mostly due to nonsense like this. 

[mrm1018]

I can’t hardly believe this was 3 years ago already!

[autodesk7K5YK]

I found this thread because I am learning Fusion 360 for the first time and was like "wtf is an ouncemass???" so I searched for it online

It's amazing to me that this confusing name is still around. Can you believe it's been 6 years!?! 🤣

[mrm1018]

Yeah, I've kind of given up on it.

Fusion 360 is a contradiction at times.  It's very refined in advanced areas, and less than refined in some basic areas.

[claytonbutton]

Autodesk, please consult some industry standards for consistent unit systems in engineering analysis and allow users the ability to define a self-consistent unit system.

Examples of consistent unit systems can be found here:

https://femci.gsfc.nasa.gov/units/index.html

Different standards are popular in different countries.

Some of the prior comments ("So, should the dialog show mass or weight? Or both? Can someone from Europe tell us how much they weigh?") are really revealing a lack of working experience in mechanical engineering.

[alanRB8YY]

It's crazy that this is still not resolved. Almost nobody in this industry uses ounces, but inches are extremely common in design, up to a surprisingly large size. Not being able to toggle units within the properties dialog that displays part/assembly mass is the extra slap in the face.

Similarly, not being able to easily toggle measurements or dimensions from imperial/metric in various scenarios is a disservice to anyone who works in a mixed unit environment. Need to spec a metric bearing in a part for a company that designs in imperial? Guess you're multiplying by 25.4 in your head every time you measure anything in the model.