UNITLESS PARAMETER NOT ACCEPTED WHEN ATTEMPTING TO USE IT AS A DIMENSION IN A SKETCH

[brady5acct]

If I define the following User Parameter:

Name=FirstActualDimension, Units=no units, Expression=1, Value=1

and try to select it in a sketch for a dimension it shows red and isn't accepted.

If, however, I assign FirstActualDimension to the appropriate Model Parameter in the Parameters dialog box outside of the sketch it is accepted - but isn't right. I'll attach a screenshot showing everything.

The background is that I am trying to create a "123 Block" that will create a block based on inches or mm. A user enters 3 values: FirstDimension, SecondDimension, ThirdDimension and a "1" or a "2" for UnitsOfMeasure. "1" selects inches and "2" selects mm. (DimensionMultiplier can also be set by the user to proportionally magnify the sizes of the block.)

Everything seems good in the screenshot where I assigned "FirstActualDimension" to Linear Dimension-2 in the Change Parameters dialog instead of trying to do it in the sketch. It isn't good though. The value for Linear Dimension-2 is 0.394 instead of what is shown for FirstActualDimension. (1 / 25.4 is 0.0394)

So, I have two problems:

1. Why can't I assign FirstActualDimension to the dimension while the sketch is open?

2. Why doesn't the value assigned to Linear Dimension-2 match the FirstActualDimension Expression value?

Update:

I saved, exited Fusion, reentered Fusion, opened the Change Parameters dialog and now the FirstActualDimension name in the Expression field of Linear Dimension-2 is red.

For the heck of it I tried to:

Add "in" (for inch) after FirstActualDimension. If I just put "in", it didn't like it.

If I instead put in "*1" it turned black, so I exited the field and could see it changed the expression to "(FirstActualDimension * 1 ) * 1 in" (all black).

Please explain the "(xxx * 1) * 1 in" syntax.

Thanks,

Rich

[TheCADWhisperer]

@brady5acct 

Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?

[jhackney1972]

---

@brady5acct wrote:

If I instead put in "*1" it turned black, so I exited the field and could see it changed the expression to "(FirstActualDimension * 1 ) * 1 in" (all black).

Please explain the "(xxx * 1) * 1 in" syntax.

Thanks,

Rich

---

If you multiple your unit less dimension by 1, Fusion 360 will automatically add the * 1 in because it assumes you want to convert the parameter to inches.  The * 1 in is just its way of converting a unit less value to the default units of the model.  If you had typed "FirstActualDimension * 1in" instead of just 1, it would have not added the extra * 1 in to convert it to the default units.

[brady5acct]

Thanks John.

Do you think it would have worked the same way while I was in the sketch (versus outside of it in the Change Parameters dialog)?

Is there some document that explains how Fusion deals with unitless parameters? (Something that would have told me to add the "*1")

Thanks again for the quick answer,

Rich

[jhackney1972 · Accepted solution]

Yes I believe so.  I do not know of any documentation describing this particular process just observation.