topic Dimensions entered as equations stay equations in Fusion Design, Validate & Document Forum

Dimensions entered as equations stay equations

mcnurlin — Sat, 22 Jul 2017 15:55:13 GMT

When I enter an equation for a dimension value Fusion 260 solves it and creates the correct size geometry. If I go back and edit the sketch the dimension value remains an equation with a little added "* 1in" thrown in there.

In the example below I'm modeling the body of a hydraulic cylinder. The dimensions from the manufacturer show the bore and the cylinder wall thickness. So to get the correct OD I typed in 2 + (.1875*2). This is the a 2 inch bore with a .1875 wall thickness. When I go back to edit the value I expect to see 2.375 instead the equation remains.

In the below example it's even more confusing. The manufacturer showed various dimensions to determine the body length. I typed them in and now when I try to go back and edit the value the equation is still there but it is truncated by the dialog box so I can not see the entire equation.

Generally I use the dimension input box like a calculator I just want to see the end result. If I need something driven by an equation I would use parameter values.

Re: Dimensions entered as equations stay equations

lucasproko — Sat, 22 Jul 2017 16:13:54 GMT

Hey @mcnurlin,

I appreciate your detailed posting, and can see how it can be a bit confusing in certain situations. The behavior is this way because many times equations hold referencing values to either user parameters, or dimensions in the same sketch (see below), in which case it's important for the equation to stay put.

Since this seems more like a feature request than a design question, I would recommend making an Idea Station Post outlining your suggestion and seeing if it gathers ample support amongst other users!

Have a great weekend,

Lucas

Re: Dimensions entered as equations stay equations

mcnurlin — Sat, 22 Jul 2017 17:09:22 GMT

I'll pass along the suggestion. Your example is completely different. You are creating a dependency to "d1" in this case the equation has to remain because "d1" has become a variable. The example I showed was just a collection of numbers entered as if the dimension box were a calculator. No dependency was created so there is no reason to retain the equation.

Re: Dimensions entered as equations stay equations

lucasproko — Sat, 22 Jul 2017 17:18:10 GMT

Hey @mcnurlin,

I understand there is a difference, but I was using it as an example of why you would want the equation to maintain its status. Even if the equation is all numbers, I can imagine situations when you would like to see exactly how you arrived at a given number (i.e. if you have a tolerance you're incorporating).

If when you go back to modify it and you don't want the equation anymore, you can always just replace it with the updated number using the initial equation result as your reference as the sequence of photos below illustrates. However, if this workflow is still frustrating to you and you don't see the value of having the equation persist, then the IdeaStation would definitely be your next best step!

Thanks,

Lucas

Re: Dimensions entered as equations stay equations

TrippyLighting — Sat, 22 Jul 2017 17:29:23 GMT

Formulae are kept:

1. because they might continue references to other dimensions - agreed, that's not the case here.

2. because they convey design intent.

Those are features!

So, if you want to convert that formula into a numeric value, then that would be a different feature.

In the meantime use a calculator. I still have my HP 28s. For simple stuff I do it directly in spotlight (on the mac)

Re: Dimensions entered as equations stay equations

mcobb — Sat, 02 Jan 2021 16:45:02 GMT

I have wanted the equations to be able to persist fir a long time. The “narrative” of the variable and equation logic can get quite complicated and I was surprised that I could not get is to permanently display.