Start by realizing that all measurements in KiCad are always metric. KiCad uses 32 bit integers with nanometer resolution internally, and everything non metric is rounded / approximated. (To make it fit in Nanometers. KiCad does not just throw away precision).
If you look at the properties of a dimension, you can change a lot of it’s properties. “Units” can be automatic (then it follows the GUI setting), or fixed to one of the units. The other boxes mostly speak for themselves, or you read the manual from the help menu, or from: PCB Editor | 7.0 | English | Documentation | KiCad
One inch is exactly 25.4 mm, and one mill/thou is exactly 0.0254 mm or 25400 nm. You’d need to be working at millionths-of-an-inch for nanometer-level precision to need rounding. And I suspect there are better tools than KiCad for VLSI wafer fab…
It can be irritating when some components are defined in Imperial units (usually THT) and some in metric (typical for SMD) but it’s just something that you get used to. The align and distribute tools really help to make the board neater when you’re stuck mixing unit systems.
Well, yes and no. There is a inch, the international inch, which is exactly defined as 25.4 mm. But there are a lot of other units which are also called inch that aren’t 25.4mm. Which was the main reason we adopted the metric system.
One example is a Taiwanese inch, which is 33+1/3 mm.
I am Australian. My country was Imperial 'till I was about 15 years old, when we changed to Metric, consequently, I was educated in both systems.
This has been of great benefit when dealing with electronics.
Semiconductors, and their packaging, have been, and still are, a US development, and the US was Imperial. The US semiconductor industry is converting to Metric, but it takes time and there will always be the problem of historical packaging.
Certainly, data sheet packaging is now quoted in Metric, but that is often a conversion from Imperial; the numbers change but it is still the same old package.
DIP16 is 8 X 1/10 inch or 8 X 2.54 mm. I find 8 X .1 is easier than 8 X 2.54 to multiply.
SSOP is .025 inches = 40 per inch. SOTs are .05 inches = 20 per inch… another two that are easier to work with than .65mm or 1.27mm
BGAs, however, are a new package: .8mm, so when using, the brain switches to metric.
I’m not commenting on which system is better, all I’m commenting on is: there are two systems, and, on occasions, it is of benefit to be conversant with both and be able to switch.
Not really. They have a huge mess. For example everyone uses Volt, which is kg*m^2/(s^3*A). If they where imperial they would use something like lb*in*miles/(s^3*A), but they don’t. And then they create units like Ω/ft, which is kg*m^2/(s^3*A^2*ft), which is, assuming you use the international foot, 0.3048*kg*m/(s^3*A^2). Now you have a unit which has a factor of 0.3048 in it. Why?
The other point is: You have to understand the metric system before you can understand British Imperial units. You have to learn how long a metre is and how we define it before you can understand the definition of the international inch/foot/yard …
there are two systems
Yes, the metric system and Planck units.
I wouldn’t call it a system when you have all sorts of random factors in it: 12, 3, 1760, 22, 220, 20, 2, … (and this assumes there would just be a single definition per unit. And that is just for length measurements). Can you convert between miles and yards in your head? Or even just foot and inches? Try it with cubic ft vs cubic inches. You can do it with km vs m vs cm vs mm vs µm very easily.
another two that are easier to work with than .65mm or 1.27mm
It would even be easier to work with 1mm than 0.025 inch and easier than 1.27 mm.
And then i have a breadboard that has a 2.54mm grid which i have to mount on 2 holes that have distance of 100mm.
By the way, do you say 1.2 inch or 1.2 inches?
We could save a lot of cost and make life a lot simpler if we just would use the metric system.