Autodesk Revit Architecture

[#1]

Hi I'm trying to construct a rig to drive a concept mass with some parametrically driven radii and surfaces between hitting at Tangents.

Part of the rig looks like this

It is all built with either reference planes for the static bits or reference lines for the circles and angular references. I have successfully locked the reference lines to the centres of the circles and everything flexes as required, however I am struggling to get the lines locking at the intersections between either arcs and arcs or between arcs and lines at points A, B, C & D below this geometry doesn't currently flex with the rest of the model

The Red Line represents the final geometry that I need to achieve (well part of it) I figure if I can crack this, then the remainder of the facade will follow the same principles.

Can anyone shed any light on how to achieve the constraining of references in order to construct the tangent geometry I need...? or am I going about this the wrong way...?

Any help appreciated

Cheers

Ian

[#2]

In my opinion, you are putting way too many constraints, and you are not using some features that are available in the generic adaptive template that can help you to solve this rig. This needs to be simplified, otherwise, it becomes too complicated and overconstrained.

Please see the attached illustration.

These are the features that you don't seem to be using:

1) Circles have the option of "Center mark visible".

• This means that you don't need new reference planes to control the location of the circles. Just dimension from the original cross of reference planes to the center mark of the circles.

2) Points can be hosted on circles, and their position along the circle can be controlled by parameter.

• This means that you don't need new reference planes to control the location of points along a circle. You can set the position by using the Measurement Type parameter as Angle, and then, tying the value of the angle to a fixed value or a formula. This applies to points 2, 3, 4, 5.

3) Points can be hosted by other points, and their distance can be controlled by parameter, which means that you don't need new reference planes to control that distance.

• This means, for example, that point 1 can be hosted in point 2, and point 6 can be hosted in point 5, and their distances can be tied to the Offset parameter,

If you use these features, the problem gets reduced to finding a formula to calculate the angle at which points 3 and 4 will be the endpoints of a line that keeps tangent to both circles.

[#3]

Many thanks Alfredo for the advice... It took me a while to get back into the maths, but I have managed to do it and this bit seems to work really well... Revit seems to have some strange ideas about what it believes are the most important references. I think I should have kept some reference planes between which I could centralise the centre points

|     O     |           O   |

|__EQ__|                 |

if I apply a second EQ Dimension I would expect to get this:-

|     O     |        O      |

|__EQ__| ___EQ__ |

but instead I get this...

            |   O   |   O   |

            |_EQ_|_EQ_|

............|         |        |

everything shifted right!!!

I'm also struggling to get my mass to follow the rig that I have built. changing the parameters changes the radii and the reference lines, but the mass doesn't follow it, Is this possible...?

[#4]

You don't need to use refernce planes to constraint points, though, as explained in my previous post.

A simple equal - equal constraint, that works fine all the times in the basic family editor, does not always work in the conceptual design environment, When that happens, what I do is simply provide 2 separate dimensions, and label them with the same parameter, for example "x2". Then, in the Family Types window, I make a new parameter named as "x" (without dimension), make it equal to 10 feet, for example, and then make "x2" equal to x / 2., which makes the two parts be 5 feet, and in that way I achieve the same result.

About the mass not following the rig, well, if the mass was used with "create form" selecting the rig, it should change if the rig changes.

[#5]

Sorry... I'm not using reference planes at all now. I have followed your method for the circle geometry. The only Reference planes I have for the flat building faces that I am offsetting from see whole rig based on your suggested method:-

thanks for the tips on the = dimensions, I'll have a play with those.

In terms of getting the rig to follow the curves, i can constrain the straight lines easily enough by creating straight splines between the two points. I can also constrain the curves to the reference circle, but what I can't control are the ends of the arcs that break away from the reference points/line ends.

This is just an experimental rig (not the main rig)

Any ideas...?

thanks so much for your help so far.

Cheers

Ian

[#6]

Create reference lines with the "3d snapping" option activated (at the options bar); that will "tie" the lines to the points at the circle. And, instead of arcs use Splines with 3 points; arcs are too rigid in Revit. Splines are very flexible.