SA currently supports two types of slots:
Rounded slots and square slots -are the first type. These are evaluated as 2D objects. The measurements will be projected to the nominal feature plane for evaluation.
Open slots (or mid-planes) - are an evaluation of two parallel planes. Rounded slots are detected automatically so to select a slot from CAD and evaluate it as a midplane may require turning off the auto-feature detection option in the GD&T Users Options.
In order to use slots to define datums and checks they need to be manually identified in the annotation in order to be recognized in the evaluation process.
Marking a check as a slot triggers SA to search the surrounding surface faces for a representative slot feature. Only a single associated CAD face is necessary and additional face selections will only slow the search process.
In addition to a closed slot features, SA can also evaluate the position of a mid-planes or open slots. These open slots must be designated as a slot in the annotation properties using the is Slot check box. In addition, their is a requirement that 2 and only 2 parallel planar features are associated with the check. When an open slot is defined you will see the midplane displayed graphically when the check is highlighted.
In order to evaluate a slot with a material modifier a Width check must also be added to the same features. Width checks are a special case and are not the same as a Distance Between check. In order to define a Width check through the SA Toolkit a new right-click option has been added to the Distance Between check button.
A slot cannot be evaluated with a length only. It requires both a length and a width to be evaluated with a MMC condition. When both are added the most restrictive tolerance will be used.