开云体育

I agree: it's a pest.

The Kicad documentation states that "By convention, through-hole footprints have pin 1 located at (0,0) and are oriented with pin 1 in the top left."

?

This puzzles me. A footprint is a physical thing so you want its origin to be in an appropriate place that simplifies the job of positioning it on the PCB. A Pin 1 origin is fine for many parts like ICs, resistors and capacitors but this is very definitely not the case for many electro-mechanical parts like switches, pots and connectors which need to interface physically with other parts of the design. For these you need an origin that makes it straightforward to position the part on the PCB such that it interfaces in a consistent way with the outside world. For vertical pots or toggle switches for example you want the origin to coincide with the centre of the hole that the parts fits into. And for any part that interfaces with a hole in a panel, for example, you at least need the origin to be on the centre line of that hole.

?

Despite this, I still find that the library footprints of every electro-mechanical part mentioned above has its origin at pin 1. Even in the create your own footprint example in the Kicad documentation, which makes a new footprint for a switch, still insists on placing the origin at pin 1.

?

Cheers

?

ian

开云体育

Hi

I'm not 100% sure, but I think this convention as something to do with automated PCB assembly machinery.

best regards

Jorge

开云体育

Very likely, but what suits machinery often doesn't suit humans. In this case, the machine only has to orient the part, but in designing the board for a potentiometer, say, the position of the spindle centre is almost always the reference point for the board layout.

Hi

I'm not 100% sure, but I think this convention as something to do with automated PCB assembly machinery.

best regards

Jorge

On 12/04/25 23:58, Ian Bell via groups.io wrote:

The Kicad documentation states that "By convention, through-hole footprints have pin 1 located at (0,0) and are oriented with pin 1 in the top left."

?

This puzzles me. A footprint is a physical thing so you want its origin to be in an appropriate place that simplifies the job of positioning it on the PCB. A Pin 1 origin is fine for many parts like ICs, resistors and capacitors but this is very definitely not the case for many electro-mechanical parts like switches, pots and connectors which need to interface physically with other parts of the design. For these you need an origin that makes it straightforward to position the part on the PCB such that it interfaces in a consistent way with the outside world. For vertical pots or toggle switches for example you want the origin to coincide with the centre of the hole that the parts fits into. And for any part that interfaces with a hole in a panel, for example, you at least need the origin to be on the centre line of that hole.

?

Despite this, I still find that the library footprints of every electro-mechanical part mentioned above has its origin at pin 1. Even in the create your own footprint example in the Kicad documentation, which makes a new footprint for a switch, still insists on placing the origin at pin 1.

?

Cheers

?

ian

开云体育

Hi

Yes I know.

I don't know how others do it, but I use one of the technical layers to draw alignment marks of pots, LEDs, switches and other such parts.

Best regards

Jorge

开云体育

That is certainly a good suggestion. Better than battling with two offset co-ordinates for each part.

Hi

Yes I know.

I don't know how others do it, but I use one of the technical layers to draw alignment marks of pots, LEDs, switches and other such parts.

Best regards

Jorge

On 13/04/25 23:25, John Woodgate wrote:

Very likely, but what suits machinery often doesn't suit humans. In this case, the machine only has to orient the part, but in designing the board for a potentiometer, say, the position of the spindle centre is almost always the reference point for the board layout.

On 2025-04-13 23:19, Jorge Ferreira wrote:

Hi

I'm not 100% sure, but I think this convention as something to do with automated PCB assembly machinery.

best regards

Jorge

On 12/04/25 23:58, Ian Bell via groups.io wrote:

The Kicad documentation states that "By convention, through-hole footprints have pin 1 located at (0,0) and are oriented with pin 1 in the top left."

?

This puzzles me. A footprint is a physical thing so you want its origin to be in an appropriate place that simplifies the job of positioning it on the PCB. A Pin 1 origin is fine for many parts like ICs, resistors and capacitors but this is very definitely not the case for many electro-mechanical parts like switches, pots and connectors which need to interface physically with other parts of the design. For these you need an origin that makes it straightforward to position the part on the PCB such that it interfaces in a consistent way with the outside world. For vertical pots or toggle switches for example you want the origin to coincide with the centre of the hole that the parts fits into. And for any part that interfaces with a hole in a panel, for example, you at least need the origin to be on the centre line of that hole.

?

Despite this, I still find that the library footprints of every electro-mechanical part mentioned above has its origin at pin 1. Even in the create your own footprint example in the Kicad documentation, which makes a new footprint for a switch, still insists on placing the origin at pin 1.

?

Cheers

?

ian

--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only If something is true: * as far as we know - it's science *for certain - it's mathematics *unquestionably - it's religion

Virus-free.