Move arcs/round traces while keeping centre locked while maintaining DRC clearance

Moving rectangular traces as close as DRC allows is easy:

However, I failed doing the same with round traces. I’d like to shove them together as close as DRC allows. But the centre keeps moving instead of the radius:

How can I grab a handle to adjust the radius without changing the arcs centre?

Version: 9.0.1+1, release build

Use Ctrl . . .

Sorry, but that doesn’t change a thing. The behaviour is exactly the same. Does this work for you? If it does, what am I doing wrong?

Thanks to johnbeard’s hint to use “Keep arc center” I managed to move the arc. However, in contrast to rectangular traces it doesn’t respect the clearance to other traces (resulting in DRC errors):

So I’m halfway there, but not quite.

Sorry, the Ctrl thing was a red herring . . . I don’t even need to use Ctrl, I just click the end or mid point and drag and the radius changes.

Bingo . . .

image

I found out why the clearance is not respected. The net automatically keeps changing. The bottom trace has net “Net-(J1-Pin_2)”, the top trace has net “Net-(D1-K)”. When moving the bottom trace closer to the top trace, it automatically becomes “Net-(D1-K)”, so the DRC is not violated since they’re on the same net:

Why is it doing that? It doesn’t happen with rectangular traces. Rectangular traces can’t be connected if they belong to different nets, KiCad won’t let me (and rightfully so). Another observation: Rectangular traces have the clearance area shaded (see yellow arrow), round traces don’t. Is that on purpose? Did I misconfigure something here?

Moving a rectangular trace:

Moving a round trace:

This happens because the track is not connected to any pad. And behavior with linear track segments is the same. When tracks are not connected to any track, their net name automatically changes to any other net they get connected to.

For the rest. You are drawing graphical arcs on a copper layer, not copper tracks. There is a difference between copper tracks (from the Route menu) and graphical objects (from the Place main menu). In older KiCad versions, graphical objects were completely ignored by DRC, later KiCad always generated DRC errors for tracks intersecting with graphical objects. In KiCad V8 a new function was introduced and graphical objects can have a net name, and thus become part of a copper conductor. But there still are differences. Graphical objects do not get shoved by the Push 'n Shove algorithm for example. It’s likely also the reason you don’t see a clearance outline around your graphical arcs. (Same for me in V8. Maybe graphical objects should show a clearance outline if they have a net name. Maybe that’s worth a bug report).

Also, using graphical arcs on a PCB like this may still be the best solution. Arcs can be part of tracks (so not graphical arcs) but only as fillets, and they don’t keep their center. But that was in KiCad V7 (V8) and with such fillets it would be very annoying to draw a PCB like this. Now graphical arcs can have a net name, they can be part of a net and they can be used as you do, but there still may be some limitations and differences. I don’t have much experience in this niche.

I don’t think that’s the case. I’ve connected the track to a pad and the behaviour remains the same:

I also did a small test and two rectangular tracks with different nets behave the way I expect them to behave: they don’t just switch nets automatically and maintain the respective track clearance:

Correct. I cannot convert arcs to tracks because after that they can’t be modified in any way shape or form and don’t behave like regular (=rectangular) tracks. They can’t be moved, extended, radius changed, shortened, shoved, dragged, etc. They are immutable once you convert them to a track.

Which is unfortunate. For the reasons stated above arcs as tracks are just not usuable. You have to maintain the graphical object property to avoid redrawing your board over and over again.

How are round traces supposed to be used? If the answer is “as graphical objects” then they should behave like normal tracks and allow shoving, showing track clearance and maintain the assigned net. If one is supposed to convert them to tracks, then I’m afraid the current state is “not ready for production” because round tracks are basically immutable, which is a nightmare to work with.

TLDR:
Going back to my initial problem, which is not yet solved: I have created a round trace (graphical object) with a net assiged. And I want to draw a 2nd round trace (different net) as close as possible (respecting clearance) to the 1st one. With rectangular tracks it’s simple (see videos above), you just hit D and shove them together.

But I don’t know how to do the same thing with round tracks?