topic Re: Parameters - mm2 (square milimeter) unit missing in Inventor Forum

Parameters - mm2 (square milimeter) unit missing

j.pavlicek — Mon, 29 Jun 2020 11:04:42 GMT

Hello, I want to create some User parameters where Area is stored (and used in another parameter calculation). But there are only circular_mil availible in Area units.

What to do now?

(I'm able to calculate this (area) parameter without units "ul", but this is nasty workaround...)

Thanks.

Re: Parameters - mm2 (square milimeter) unit missing

admaiora — Mon, 29 Jun 2020 12:19:30 GMT

You can create it

Re: Parameters - mm2 (square milimeter) unit missing

Fouad-l — Mon, 29 Jun 2020 12:22:52 GMT

Hi @j.pavlicek.

What i do in this case is write unite area directly (e.g mm^2) in unite specification.

Re: Parameters - mm2 (square milimeter) unit missing

johnsonshiue — Mon, 29 Jun 2020 20:45:57 GMT

Yes! Fouad and Matteo are both right. Another way is simply typing in "mm*mm" as the unit. Inventor supports combo unit from base units.

Many thanks!

Re: Parameters - mm2 (square milimeter) unit missing

Bearded_Engineer — Fri, 01 Aug 2025 11:19:10 GMT

So how do we do this with mm^3 (Cubic) and mm^4 (Moment of Inertia)?? Since anything longer then mm*mm is not accepted as a unit??
Gonna have to make everything unitless now... I think the table I'm working on was a default structural shape table in CC (might have been a copy) which has a lot of missing units, so any changes to the table throw a whole heap of faulty columns.

Re: Parameters - mm2 (square milimeter) unit missing

johnsonshiue — Mon, 04 Aug 2025 20:19:35 GMT

Hi! Did you try typing in "mm^3" or "mm^4" in the Unit dialog? It should work.

Many thanks!

Re: Parameters - mm2 (square milimeter) unit missing

Bearded_Engineer — Tue, 05 Aug 2025 11:28:23 GMT

Hmmm my bad, it seems like the unit is not the issue but rather CC not recognising that it should add up to mm^4 and thus refusing it... The units were not available in the dropdown and that combined with multiple red inputfields made me jump to the conclusion that the manual mm^3 or 4 unit input was the issue. Tried it with an empty expressions field and that does accept mm^3 and mm^4. I'm using some rather lenghty formula to calculate a few things like Moment of Inertia in an existing table, so there is some history that I need to work through. I know the resulting value should be mm^4 but I'm having a hard time getting the CC to accept both the formula and the unit at the same time. (So I decided to make everything unitless to get the numbers for now...)

After a lot of trial and error, I think I found my main issue were I went wrong. The normal Parameter menu automatically adds UL to any constant values and the Expression field in CC does not. Somehow CC is very picky for certain positions with just numbers where it will go balistic. For example 2*X will run fine, but for (2*X)^2 the power value unit triggers an error when used in something more complex. adding UL to any and all numerical values seems to solve it so far. So comes down to user error, triggerd by expectations that math behaves the same way in all input field. Would be great if there was some more feedback on input errors. The parameter menu does this a bit better already, telling what it's expecting.

Maybe this post helps someone with similar issues in the future.

Edit: Little strange though, when I go back to edit the Column Porperties the units field has been emptied and the expression field turns red again. Have to input the unit again each time you repeat this...

Re: Parameters - mm2 (square milimeter) unit missing

johnsonshiue — Tue, 05 Aug 2025 20:47:05 GMT

Hi! I could be wrong but I don't think Content Center supports custom unit (not the one offered in the Unit dialog).

Many thanks!