topic Re: User Parameters in math functions in Fusion Design, Validate & Document Forum

User Parameters in math functions

7P332B5QTVW4MF — Wed, 07 Feb 2018 21:26:39 GMT

Hello,

I'm trying to tessellate some hexagons with the rectangular pattern tool but I am coming up against some problems in the User Parameters.

I need to reference the hypotenuse of a triangle to get one of the side for the X spacing of my pattern. I'd like to drop this equation in as a User Parameter:

sqrt(pow(4*hexrad+2*spacing;2)+pow(2*hexrad+spacing;2))

But I can't put a parameter into the sqrt function. I need Fusion to do the trig to get spacing right. You can see the needed dimension on my screenshot. It resolves to 19.053.

This would be easy if the driven dimensions had names that I could use further along in the design.

Anyone else have an idea how to make a parametric grid of hexagons?

Re: User Parameters in math functions

MichaelT_123 — Thu, 08 Feb 2018 06:58:08 GMT

Hi Mr Eagleapex

.... for hexagon structures you might consider using circular pattern(s) and deselect unwanted tiles (manually or programmatically).

Regards

MichaelT

Re: User Parameters in math functions

TrippyLighting — Thu, 08 Feb 2018 13:19:06 GMT

Or you can use Fusion 360's way to conveniently reference other dimension in the same sketch and use simpler math.

But to answer the initial question, yes, you canuse formulae in user parameters.

Re: User Parameters in math functions

Theoforus — Mon, 23 Oct 2023 11:28:49 GMT

Interesting. I am trying to do the same and came across your explanation. Seems like a good solution. Anyway ... could you answer why I can not use the ratio_hexagon_.... parametric value in other parametric values?

Re: User Parameters in math functions

laughingcreek — Mon, 23 Oct 2023 15:18:11 GMT

i haven't digested your question yet, just starting my first cup of coffee. my first thought is that ratio's are inherently unitless, but your parameter "ratio_hexagon_radius_vs_point" is in mm. you probably need to make that a unitless variable in order to use it in equations.

Re: User Parameters in math functions

simon.dyer — Wed, 24 Jan 2024 00:39:18 GMT

I believe the OP question was to use parameters in formulas, not vice versa.
Eg to get the angle from my parameter using this formula,
asin(MyParameterValue)
cannot be evaluated.
I have tried all methods I can find and now asking here.
Please see below images.

Re: User Parameters in math functions

jhackney1972 — Wed, 24 Jan 2024 01:32:54 GMT

Works OK for me. See Screen Capture below.

Also see the solution to your Forum Post here.

Re: User Parameters in math functions

laughingcreek — Wed, 24 Jan 2024 02:25:05 GMT

you can now reference driven dimensions from a sketch out side of that sketch, and use them in formulas and other features. Being inherently lazy, I prefer to let fusion solve these types of things rather than using trig to do it. I have seem very few cases where it was actually necessary to use trig. letting fusion do it for you has the additional advantage of a adding visual elements, which will be much easier for someone other than you to figure out what your design intent is.

Re: User Parameters in math functions

HughesTooling — Wed, 24 Jan 2024 09:34:57 GMT

@simon.dyer wrote:

I'd guess the problem is you created a parameter in mm then changed it to unitless? Trouble is Fusion seems not to make a true unitless parameter and still sees it as mm.

I get this after changing a mm parameter to unitless.

And it works if I cancel the units. Seem to remember this bug being reported but not sure if it was accepted as a bug of just another Fusion Feature!

Re: User Parameters in math functions

laughingcreek — Wed, 24 Jan 2024 14:17:21 GMT

@Phil.E - see post 9

Re: User Parameters in math functions

simon.dyer — Thu, 25 Jan 2024 12:52:35 GMT

Many thanks for resolving that 'feature' for me - how did you know to divide by mm ?

Re: User Parameters in math functions

HughesTooling — Thu, 25 Jan 2024 14:29:40 GMT

@simon.dyer wrote:

Many thanks for resolving that 'feature' for me - how did you know to divide by mm ?

You can cancel a parameter's units by dividing by the parameter's units. You can see in my pictures it still shows mm in the tool tip even though you changed the parameter to unitless.

If you create the parameter as unitless from the start it will work without any canceling of units.