Greetings - I’ve put this question in the schematic section because that seems to be what controls the BOM. Context: KiCad 6.x
Let’s start with an example. I have a plastic 2 C-cell battery holder that attaches to a circuit board with 4 screws and two solder connections. So, it is a regular component with a symbol and a footprint.
The question: how to get the screws on the BOM? It seems plausible that a screw symbol would do it. Is that how folks handle it? What sort of symbol is used?
The battery holder includes the pads and holes for the screws in the footprint. I want to do that to insure hole positioning relative to the battery holder outline. That would leave the screws without any footprint. Is that a problem?
if you want it to be part of the BOM I would add an extra symbol for it. I don’t think there is any convention on a “electrical” symbol of a screw so you can use any symbol which marks it as a screw for you and whoever else uses this schematic.
not at all. you can just mark them as Exclude from board in the symbol properties so they will only show in the schematics. I am not completely sure if this function was already available in v6 as I have used v7 for a while now.
I place at my PCB 1/2 of EE ferryte. On its legs I place a small PCB with coil. That PCB has 3 pins. It is connected with main PCB with 3 pin header. That PCB footprint has no pads - only circles to show where pin-header should be placed. E ferryte (obviously no electronic connection) has footprint containing only courtyard rectangle, but it has 3D model (this small PCB footprint also has 3D model).
So at PCB I place 3 footprints one on another.
I think your screws are like my ferryte.
Here is how it looks in 3D view:
I don’t use the KiCad BOM directly. I import it into my (very simple) ERP-system. In your case, let’s say, stock number x is the battery holder, y is the screw and z is “Battery holder with mounting”, has its own BOM containing x and 4*y. In KiCad I can then use z as stock number so I don’t forget to order the screws as well.
Thanks for the suggestions. V6 symbol properties have options “exclude from BOM” and “exclude from board”. I had never noticed those. I think that I can come up with a symbol. I am not yet good enough with FreeCad to make a good 3D drawing but the rest should work well. That should solve things for me. - Jim Wagner
FreeCAD has a “fasteners workbench”. It generates 3D models on the fly. You just enter the data for the sort of screw, nut, washer or whatever you want and some data for diameter and length and you have a 3D model of your fastener.
I was watching my mechanical designer creating an equipment model on Solidworks and he was simplifying screws to keep file size and rendering times sane. A screw thread is a lot of segments
The Fasteners workbench has been in FreeCAD for probably more then 5 years, but you had to install it separately. I think it is now part of the standard installation of FreeCAD. And there are quite a lot of them too. Below a small composition of the available icons / types:
Adding the threads is an user option in the FreeCAD Fasteners Workbench. Below a screenshot of two M3x12 screws of type DIN967. With and without thread.
And there are other tricks too of course. You can make either real copies, or make clones (which is just a link to another fastener) But for the most part I do not even add fasteners. I create one to check clearances and such and for all the others I just draw the holes.
