Changing the units of a user defined parameter does not work.

[Julie_7]

I was so excited to notice that in the parameters dialog that I can now click on the units for a parameter and change the value. I often forget to change the count of something to have "no units".

I just created a new design, opened parameters and added

- x_unit 50mm

- y_unit 50mm

- x_units 1

- y_units "no units" 1 which made me realize that I had forgotten to change the units to none for x_units.

- So I clicked on units for "x_units" and changed it to "no units" and it changed the expression to "(1 mm)/ mm" which seemed strange. I then changed the expression to 1.

- When I went to use the parameter in an expression for a length in a sketch it failed. (x_units * x_unit). By failed I mean the expression was red and I could not save the value.

While recreating the issue for this writeup, I found that I can only change the units in the parameter dialog before the parameter is used somewhere.

Regardless whether I leave the strange "(1 mm)/ mm" expression, or change it to be just one, the parameter is treated in the sketch as if it had units and the expression is invalid.

More information:

- If I then change from "no units" back to mm the expression stays unchanged as "(1 mm)/ mm" which is incorrect. However the value which had been "1" now changes to 10.00 which is even worse.

I am using Fusion 360 2.0.17954 x86_64

[jhackney1972]

When you change the units from mm to No Units, Fusion 360 can only do one thing to fix the units and that is add the / (divide) by 1mm.  If you remember from your basic algebra class, to remove units, you divide by 1 of the unit, in this case 1mm.  This is normal.  When you want to change it back to mm, then your change the units and "you" must remove the "/1mm" from the expression the expression value to 1mm. 

As far as changing units after a parameter has been used is not possible.  Fusion 360 must preserve its integrity of used units or your sketch would lose definition.

[Julie_7]

@jhackney1972 

I think you missed the critical part of my post. I should have made it more clear. Sorry.

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@Julie_7 wrote:

Regardless whether I leave the strange "(1 mm)/ mm" expression, or change it to be just one, the parameter is treated in the sketch as if it had units and the expression is invalid.

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What I was intending to identify as not working:

I thought that changing to no units just after creating the parameter was a time saver and better than deleting the parameter and starting over. However, after changing it to no units, when I later try to use the parameter in an expression that fails because F360 does not treat it as a unit-less number.

In addition, although you are correct that to remove units dividing by 1 mm is correct as an expression, there is no reason not to then cancel the units and show the result as just "1" in the expression. That might also be part of the fix for the above bug.

[TheCADWhisperer]

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@Julie_7 wrote:

That might also be part of the fix for the above bug.

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Can you Attach a file here that illustrates this "bug"?

[jhackney1972]

I can see your issue now.  In the video I replicate it when I change an inch user parameter to No Units and then try and use it in a Circular Pattern.  Until this is looked at and fixed, I offer a workaround in the video.

@Phil.E , I wanted to call your attention to this please.

[Phil.E · Accepted solution]

Thanks. This is known and some solutions are being discussed. (FUS-138728)

[Julie_7]

John:

I woke up this morning thinking about your comment about changing units.

"As far as changing units after a parameter has been used is not possible. Fusion 360 must preserve its integrity of used units or your sketch would lose definition"

1. If units is changed to "no units" when the expression is not compound, there is no benefit to keeping the units in the expression (1mm/mm). Just change the expression to "1". This is obviously what I want.
2. Even after a parameter is used, changing the units should be allowed within the same class (length, angle, etc.) as this does not change the stored value which is always in cm and therefore none of the model calculations are affected. If the expression for the parameter is just a literal value when the units is changed then just converting the literal to the new units and putting that in the expression is likely what the user wants and should not cause any problems. (For example, if I have a parameter with units as mm and expression as 1000, then changing units to meters can just change the expression to 1.)

A related though about units...

For any design the default units must be specified. However, when there is a need to enter a value in different units, it would be nice to have the option to display units as entered, or as noted in the parameter list.

While writing the above paragraph, I did some experimenting and realized that how it works now, and what I am used to, is not what I would consider logical.
Example:
I draw a rectangle on a sketch and enter 10 for the height and 3" for the width.
I open the parameters and go to that sketch and find that both height and width have units set to mm (the design default) and the value of width is 3".
I would find it logical that implicit parameters would get created with units set to the default if units are not specified, but with units set to the specified type if that is specified in the field during the sketch.
In addition, if I go to the trouble to specify non-default units for some dimension then I might expect that that is important information and the units should be shown on the sketch for that dimension.

Of course, this might just be the ramblings of a computer programmer who is not an expert in CAD. 🙂

[Phil.E · Accepted solution]

Thanks again for reporting this.

The major release that came out yesterday has this fix. Please give it a try and let us know if all the cases are solved now! (build 2.0.18719)

[masterct]

I have the following version (which is later than the one mentioned where this was supposed to be fixed) - see below:

Fusion 2.0.19966 arm64 [Native]
Active Plan: Subscription
macOS 14.5 (23F79) on Mac14,15

I was creating Parameters and defined one to be the Percentage of the Total Width but when I tried to use it I got the following Error:

Parameter's expression edit failed.

Units mismatch between expected inch and evaluated inch*inch. Please provide a valid expression.

After much digging I found the .333 evaluated value of 1/3 by Fusion had created 1/3 * 1 in.  And now I understand that when I used it with another parameter that was defined as inches, it was trying to do inch*inch (not what I would have intuitively expected - thinking that it should be fine - they both are in inches.  Fusion does appear to fix this WHEN you are creating your parameter initially, BUT if you forget or don't yet understand this, the only way to fix this is to re-create the parameter...and if you are trying to keep your parameters in a specific order you are unable to do this (there's no ability to manually re-order them into a order that makes sense to the user).  So, I'm either faced with re-entering 20+ parameters that came after the aforementioned offending parameter or just have one parameter listed out of place and order. 

What is really strange to me is everything except UNITS are editable by just clicking on the Parameter Name, Parameter Expression, or Parameter Comments and it's an editable field.  Why can't I click on the Parameter Units (or the User Parameter on the very left) and be shown a popup or just simply popup the original dialog and I can change any of the values there.  So, in summary, my two requests are:

1) A way to edit the Units AFTER you've created the parameter (this allows to be able fix unit issues after you get the warning)

2) User control to manage the order of the presentation of the parameters - beyond simple sorting by name, expression, etc.

Chris 

[Phil.E]

Thanks for posting about this. If you could share a sample design, without any geometry, but with a parameter table set up to show the issue, that would help.

What I think you are seeing is that you can't change the units of a parameter if it is already referred to by another parameter. If you try to delete it, the warning says why:

If a parameter is not consumed by another parameter, or a feature, you can change the units freely.

The improvement ticket (already logged) to add UI elements like sorting to the parameter table is FUS-93068.

Some good news you might enjoy: there are some improvements for the parameter table coming that might help: export/import parameters is due for release next month.

In the meantime, you can try it out by joining the Fusion Insider program where the latest improvements are found.

You can sign up to be a Fusion Insider today to try it out.. 

(update: I went ahead and added an improvement ticket to add a tooltip or warning dialog to inform why for some parameters changing units is not available - FUS-168740)

[masterct]

Thank you.  That was exactly what was happening.  All my params are dependent on other parameters and so nothing happened.  So, I tried creating a testParam that stood alone, and voila! when I clicked on the units - yes indeed I got a drop down to change the units.  

Also, thank you for adding my request for the Parameters Dialog.  I'm assuming that is for the User to move them around to their on visual order (and possibly saving that order so you can come back to it later, i.e. opening the Params list likely would resort the users order, so would be good to save).  

Thanks again for your prompt and helpful explanation.

Chris

[masterct]

Thank you.  That was exactly what was happening.  All my params are dependent on other parameters and so nothing happened.  So, I tried creating a testParam that stood alone, and voila! when I clicked on the units - yes indeed I got a drop down to change the units.  

Also, thank you for adding my request for the Parameters Dialog.  I'm assuming that is for the User to move them around to their on visual order (and possibly saving that order so you can come back to it later, i.e. opening the Params list likely would resort the users order, so would be good to save).  

Thanks again for your prompt and helpful explanation.