Hello, have been reading this forum for a while now, great source of information. Recently question came up about measuring method so I would like to get advise from the experts. Based on the drawing datum A is the surface of the the stamped part, datum B is is a hole without any positional tolerance and than there is a round slot. Length and width of the slot are dimensioned separately. Length of the slot is marked as datum C and has non diametrical TP 0.25 MMC, A, B MMC with the associated basic dimension of let say 4.5 mm in X direction (looking at the drawing length is in X and width is in Y). Width of the slot has also non diametrical TP 0.25 MMC, A, B MMC, C MMC with the associated basic dimension of let say 17 mm in Y direction. Both hole and the slot are on the same plane A . At some point insert stopped fitting so measurements started at both ends (our company and supplier). My results were showing TP out with center of the slot being only 3.7 mm in X and 17.15 in Y. Company which makes inserts admitted their punch was loose but said position is still in spec. I was setting alignment by measuring 2 radiuses of the slot, creating line between their centers and rotating alignment to it, they simply used 4.5 mm basic to create offset alignment which also automatically made 17.15 in Y shorter and almost perfect. They are also reporting TP of the slot's center in only one direction since in the other direction would be perfect based on the offset. I presented position in 2 directions (thanks to all the posts regarding generic features and variables), also tried explaining that TP callout is not only for the center but any point along slot's axis. I need some confirmation or correction to my method.
Is there more geometry on drawing that constrains slot?
This is it.
The way the Slot Position works is the midpoint. The Midpoint along a single axis. The 0.25 AB True Position in example represents deviation of 4.5 Basic axis only (Length of slot is defined by brackets)
Does this mean that, if let say, slot L axis should be parallel to the bottom edge of the part but is suddenly rotated 45 degrees, as long as it's center is still at 4.5, -17 from B it's position is perfect?
No, because you still have to meet the position of the slot's width. The slot width has a TP, this TP is what is controlling the orientation of the slot, to A|B|C.
No, because you still have to meet the position of the slot's width. The slot width has a TP, this TP is what is controlling the orientation of the slot, to A|B|C.
