KiCad 7.0.9 Symbol editor.
I spend half+ hour and can’t find the solution while, at the same time I’m 100% sure I had no problem with it in V5.
I have grid set to 5 mils.
I have 180° arc (copied from my old symbol, as I can’t create such arc now) with 20 mils radius and both ends and center in grid.
I want:
modify it to have radius of 15mils and still both ends and center in grid (no matter if one end is fixed or center is fixed during my edition), or
draw new such arc.
When I modify arc by one of its ends its center loses grid. When I try to correct it whenever a centar is close to right grid position the arc jumps to the other side (other half of circle) and it looks it is not possible to get arc as I want.
When try to add new arc I can’t find how to start from selecting the center (100% that it was possible in V5). If I knew how start from center I believe the rest will work. The drawing always starts from arc end and I get the same as when trying to modify original arc.
I was trying Shift, Ctrl keys while drawing. I was trying to keep mouse at arc tool icon with hope that I will be presented other methods of drawing it.
While writing post I probably got the idea how to do it. I still have Win7 PCs with KiCad V5 installed. If I don’t find the way in V7 I will have to do it in V5 and copy.
I know that graphic arcs need not to be 100% accurate but I’m trying to do things perfect or not do them at all.
What I am missing?
Edit.
I’ve noticed that I lied. My arcs from V5 really have 179.5° so something was also not precise those time what I don’t noticed or don’t remember.
When I click ‘e’ to edit I cant edit points coordinates. How to get into such edit?
For me, while editing an arc in the Symbol Editor, KiCad drags the endpoints over the grid, while the centerpoint is moved “gridless”.
I guess 179.5 degrees is close enough for most practical uses in KiCad. If it bothers you the arc flips around, then just use r to rotate the arc until it has your preferred rotation.
Also, grid and snapping settings for the Symbol Editor, Schematic Editor, PCB and Footprint Editors are all separate in the Preferences.
In addition, you can get your arc closer to 180 degrees if you zoom in more, as the center moves with pixel accuracy. KiCad also apparently does not like 180 degree arc’s. When an arc is close to 180 degree and I “drag” an endpoint around for less than half a grid distance (so there is no actual movement of the endpoint itself) the included angle still slowly becomes smaller.
An alternative is to draw a 90 degree arc, duplicate it with [Ctrl + d] and then rotate it before you place it.
But overall I agree it is a bit limiting. There is still plenty of room for improvement of arcs in KiCad
I made close to 360° arc (RFID antenna) by using two close to 180° arcs (at 3 PCB layers). I didn’t found the way to get that arc with precisely defined center and radius. I want it to be precision to be able to made the same antenna whenever I will need it. The best would be footprint but I failed with making it as 4 layer footprint with vias and so on.
But in symbol editor I didn’t get an idea to divide it farther into smaller pieces
I think there is lack of one bit in arc definition (clockwise/anticlockwise). If it were there you will be able to have exact 180° arcs.
As, this time it was only graphic (I modified Spice sinus Voltage source to be smaller) this time I gave up with precision and sinus symbol looks even more like sinus
But I would be happy if I will be able to draw any kind of arc and it is why this thread exists. I supposed - I don’t know something.
I used a 5 mil grid in the above illustration in the Symbol Editor.I created a 90° arc with a 25 mil radius then Duplicated, Moved and Rotated.
This is easier in the Footprint Editor.
Set a suitable Grid.
Change co-ordinate system from Cartesian to Polar.
Select Arc to draw
Read R (radius) and Theta (angle) at the cursor or under the work area.
Note:
Check Arc Editing Mode in Preferences > Footprint Editor > Editing Options.
Also, the finer the grid the more accurate the arc. (compare radius at 45° with a 10mil grid and a 1 mil grid).
There is some ancient history here from V4 and V5 days. Circles and even 180 degree arcs triggered a bug in some fabs pcb gerber to panel processing.
Most of the threads about this seem to have vanished now.
I learned the trick of using 2 x 90° arcs back in 5.x.x days.
I couldn’t work out how tho make a reasonable 180° arc until one day I noticed 180° arcs in the Kicad generic transformer symbols. I placed a transformer into the symbol editor and separated the parts to find the secret.
