Gap Conditions

Modeling Gap Conditions

Posted by Wayne McClelland and Andy Wells to the ICCON Bulletin Board, 8-October-1998

Another simple application of conditional equations is to represent "gap conditions" between parts or between curves in a wireframe sketch. We'll start with a problem posed by Dave Hurst to ICCON:

	two wireframe "boxes" are separated by a gap (see the dimension "gap" in the graphic below)
	drag the righthand box to the left
	once the gap goes to zero, then the lefthand box should start moving to the left as if the righthand box were pushing it
	... and then drag the righthand box back to the right and the two boxes should separate again (one-directional contact)

Sliding Wireframe Boxes

Andy Wells was clever enough to find the full solution to the one-directional contact (Wayne only got the first half correct) and Andy's approach is presented below:

First you may want to download the model so that you can follow how this is accomplished.

Download the Universal File of the completed model

Open a new model file, enter the Design application, Master Modeler task

Options, Units... "millimeters"

File, Import, Design Universal file... enter the universal file that you downloaded

Get the "sliding-wf-boxes" part

Drag the lower righthand corner of the righthand box to the left

Steps from scratch are:

sketch the two boxes as rectangles

add the "axis" at the lower left

dimension as shown above... Modify the noted dimensions to have the names "loca", "ax", "gap", and "locb"

Part Equations... <select the wireframe>

	set ax and bx to "constant"
	set loca, gap, and locb to "from equation"
	in the equation box at the top of the form, type the equations... gap>=0... locb>=loca+ax

	now Drag the lower righthand corner of the righthand box to the left and you'll see that once the gap is closed the two boxes move together... click to accept
	Drag the same point again, but this time to the right and you'll see the boxes separate again
	You can also get related effects by Dragging corners of the lefthand block