Tangent edge transition standard

[Stick369]

We have a part with a cylinders that transitions to a larger diameter with a tapper at both ends of the tapper there is a transitional radius/fillet. See attached image_1

The vender recently devlivered a batch of parts with an "undercut near the smaller diameter. See attached image_2

Their position is that because the drawing doesn't say they can't put in an the "undercut", its allowed. Insert mental image of lots of dumb looks. I'm having an issue finding which standard covers the intent, or purpose, of a tangent lines representation. Something that says a tangent edge represents the transition between two continuous surfaces. Or something that say unless the geometry is on the print, its not supposed to be there.

 

[powerhound]

This thread shows the importance of using GD&T to define design requirements. There doesn't seem to be one speck of GD&T here so I'm not at all surprised by this result. As someone else mentioned, using profile of a surface to control the part geometry would have prevented all this. If the part doesn't violate anything on this drawing then they are compliant. It's always these unforeseen circumstances that cause people to step back and realize that a better method than +/- tolerances to locate features is needed. Is it the case that these parts have been made for years with no issues? If so, everyone probably thinks the print has no problems. Now that this has happened, it turns out the print actually does have problems. There doesn't need to be a radius at all at that intersection so how can you reject it if it meets all the other dimensions and tolerances. Just saying you don't like how it looks, or that it doesn't look how you expected, is not a rejectable item.

John Acosta, GDTP Senior Level
Manufacturing Engineering Tech