Footprint dimension does not match the provided product

Hi,

I am designing a simple PCB on KiCAD to be manufactured. On the footprint editor in the schematic window, there are descriptions and links provided to the product the footprint. However, when I use the measure tool on KiCAD to measure the dimension of the footprint, it does not match the dimensions of the datasheet of the product on the website (or it might be that I am misunderstanding the technical drawing)

My specific case: I am using the footprint of BNC_TEConnectivity_1478204_Vertical, (https://www.te.com/usa-en/product-1-1478204-0.html?source=header-match)

On the technical drawing: https://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Customer+Drawing1478204CpdfEnglishENG_CD_1478204_C.pdf1-1478204-0

There’s the component that says the legs are 8mm apart, however there are also mounting holes (which matches the dimensions in the schematic, about 6.3mm), I’m a little confused, what is the difference?

Thanks

Every footprint has a datasheet link in its description. That datasheet is the reference. So as a first step check if the linked datasheet is different than the one you have.

The dimension that you are interested on to make your board are the mounting holes, the other dimension are the ones of the physical component.

The discrepancy that you see between the 8 and the 6,25 is that one is the side of the a square and the other one its diagonal.

image (6,25*~1,41 =~ 8,83)

Hope this helps.

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Always use drawings which shows recommended layout for components, also pay attention to the value of the dimension ( inch or mm).

I have to strongly disagree with the use of the word “Always”. While the suggested footprint is a good starting point, it is by no means certain that it fits the needs of your manufacturing process perfectly.
In fact it can by definition not really fit as the part manufacturer has no knowledge about your particular PCB process (one size fits nobody perfectly). However notice that it will fit most users well enough to be a viable option (most users do not need a perfect fit as their process is not optimized anyway).

In other words: I would argue one can only use the suggested footprint if one does not care about manufacturing yield. Otherwise one will completely ignore the suggested footprint and use the part dimensions including tolerances with the manufacturing parameters to get to a footprint more closely matching ones particular requirements (For example by use of IPC suggestions).

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Fair enough. In my work Im using accurate measurement of recommended layout for pads and mounting holes, but outline of component try to draw that better meets the physical dimensions of component.

Yes, thank you!! Thank you everyone else for the useful feedback/tips.