How to add polygon or pattern constraint ?

[Anonymous]

Dear forum members,

In a sketch I want to lengthen the line of 51 mm shown below.

When I tell fusion 360 to that, it doesn't, but tells me in stead :

“Error: Failed to solve.

Please delete or modify one of the following constraints/dimensions”

As far as I know, the way to reslove such issues, is to delete stuff, until Fusion 360 finally consents to allow the change one wants, and then add readd all the stuff one deleted.

However, that line is part of a 48-sided polygon and I don't know how to readd the polygon constraint, other than with undo or deleting the entire polygon and readding it.

So, how could I add the polygon constraint after having made the change required to be able to change the dimension ?

[Anonymous]

Thank you for your suggestions. I vaguely remember I could modify the number of sides as well, but I may be confusing with patterns.

davebYYPCU 13 : Left click the polygon icon to select it, right click, select Edit polygon.

I don't see an Edit polygon option.

TheCADWhisperer 14 : If you have any idea up-front that the number of sides might vary - you should model only one side and pattern feature rather than sketch (which is basically what a sketch polygon is - a sketch pattern).

Are you suggesting to create the pattern in 3 dimension i.s.o. the sketch ?

davebYYPCU 13 : Was from muscle memory, been a while since I have done it, and 

you can change the count in the parameters window too,

Where can I find that parameters window ?

[TrippyLighting]

I can enter the number of sides on my macOS version of Fusion 360:

 

However, once the polygon is created the number of sides is not editable and there is no parameter for it. This has always been the case. Unfortunately!

[TheCADWhisperer]

---

@Anonymous wrote:

Where can I find that parameters window ?

---

I use this enough that I put on the ribbon.

In this case I would create a Parameter with a name something like Number_of_Sides, then anytime I want to change, simply double click on the Expression. (This could be a formula too.)

[TrippyLighting]

The sketch polygon primitive will accept the user parameter, but it will not respond to changes in that parameter. The number of sides of the sketch polygon is NOT parametric.

No, I am not kidding. I wish I were!

[TheCADWhisperer]

---

@TrippyLighting wrote:

The sketch polygon primitive will accept the user parameter, but it will not respond to changes in that parameter. The number of sides of the sketch polygon is NOT parametric.

---

In my latest example - I did not use a sketch polygon.  My sketch IS fully parametric.

Slow, but does solve.

I would pattern features instead of sketch elements.

[davebYYPCU]

Looks like I have confused it with Circular pattern, my old file revisited, yep was a circular Pattern in that one.  Sorry to those I have ......

[Anonymous]

So, a parameter could be used, but changing that parameter would have no effect. In addition, it cannot be used after the fact.

The_CADWhisperer : “I would pattern features instead of sketch elements.“

Are you saying that i.s.o drawing a polygon and extruding that, you would draw a triangle, extrude it and then use a circular pattern on it to form an extruded polygon ?

A reason to want to modify a sketch element i.s.o. replacing it is to keep the features based on that element. If I replace the polygon, Fusion 360 will complain that the original polygon is missing. Unfortunately, Fusion 360 discourages modifying things.