Driven dimension: shouldn't this work?

[GRSnyder]

Consider:

d1 is the circle diameter. Here, I have manually set it to 50mm and then turned on the "driven" flag. But in real life, it would be an actual measurement.

The goal: put the vertical construction line 60% of the way from the right edge of the circle. For example, if the circle diameter were 10mm, the line should be 6mm from the right edge.

Should it not be possible to set the other dimension, d2, to "d1 * 0.6"? But F360 won't accept it.

Please note: I do not need help placing something within a circle. There are many workarounds. I'm just surprised that the current implementation of "referencing driven dimensions" can't handle this. The circle and the line are completely independent; there is no interdependency, nothing to solve.

[WHolzwarth]

I only could do some similar by using a leading parameter named Reference in Parameters list.

[davebYYPCU]

Does it work for a driving 50mm d1?

Or are you not looking for 30mm?  (.6) 40mm is (.8)

[GRSnyder]

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@davebYYPCU wrote: Does it work for a driving 50mm d1? Or are you not looking for 30mm?  (.6) 40mm is (.8)

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Yes indeed, I am looking for 50 * 0.6 = 30mm. But I didn't want to set d2 = 30mm because then people would ask, "OK, 50mm * 0.6 = 30mm. What's the problem?" 🙂 

Here, d2 is just currently "a dimension whose value I want to set according to a formula." The value of 40mm has no significance is and just illustrative.

Edit: just to be clear, I cannot set d2 = "d1 * 0.6" and just see what it comes up with because Fusion 360 does not recognize "d1 * 0.6" as a valid formula. It is not possible to enter this formula.

[mattdlr89]

I think you can do it if you add an extra construction line tangent to the circle edge and then dimension from that one. 

[davebYYPCU]

Works as expected for a driving d1.

So having it work as driving, you can't toggle d1 back to driven, and that is not what was advertised. 

However as there are only 2 dimensions in the file, that may just be a limitation. 

Might help....

[GRSnyder]

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@mattdlr89 wrote: I think you can do it if you add an extra construction line tangent to the circle edge and then dimension from that one. 

Ha! Yes, that works perfectly. But that just makes me more suspicious that this is in fact a bug.

[GRSnyder]

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@davebYYPCU wrote: Works as expected for a driving d1.

Your d1 is not a driven dimension.

[mattdlr89]

@GRSnyder Agreed - that construction line is the same as selecting a tangent edge so you'd think it should work without it. 

[jeff_strater · Accepted solution]

yes, this is a limitation of the "driven dimensions in equations" implementation.  There are a couple of dimension types that are not supported - tangent dimension is one of them.  I forget the reason.  Some limitation in the way that the solver handles tangent dimensions.  If you create a coincident point to the circle at the point where the tangent dimension would attach, and dimension from there, you can get to the same place