topic Re: Improved Trace/Pour Geometry - Arcs / Circles in Fusion Electronics Forum

Improved Trace/Pour Geometry - Arcs / Circles

therealotterman — Tue, 07 Jul 2026 21:14:58 GMT

I am working on integrating a custom on-pcb potentiometer on my PCB. Please see this process for motivation https://www.panda-pcb.com/html/Products/Carbon-Potentiometer-PCB.html

The tool today has two issues that prevent this:
1. The existing polygon pour leaves rough edges which look unprofessional.
2. The DRC throws errors when connecting a fill across two unconnected nets, the fill needs to occupy a resistor role in this case.

In short this tool lacks the precision that users expect from the design tool kit.

The current approach I am using is to draw a thick arc and ensure enough edge margin. This take alot of time to ensure DRC passes and the part fits correctly. This approach also doesnt do the edge crop that is nice with existing pours enforcing DRC.

How to solve this?

It seems fusion is an overlay on EAGLE, no point in fighting this so I would suggest creating a graphic sketch overlay you can convert to polygon instead of just using a polygon. Reuse your excellent fusion design sketch toolkit for this and it should be alot more manageable.

Re: Improved Trace/Pour Geometry - Arcs / Circles

nnovotney — Tue, 07 Jul 2026 23:19:32 GMT

The DRC throws errors when connecting a fill across two unconnected nets, the fill needs to occupy a resistor role in this case.\

Just throw a zero ohm resistor at each end of your carbon strip . .. so now you can have net names A (left), B (strip), C (right)

Re: Improved Trace/Pour Geometry - Arcs / Circles

therealotterman — Wed, 08 Jul 2026 02:18:10 GMT

I saw that tip, but I dont see how that helps. You have to overlay the carbon on top of the stip. Seems like an ugly hack.

I can live with DRC errors, I'm more interested in creating high quality traces using something like the design sketch tool

Re: Improved Trace/Pour Geometry - Arcs / Circles

nnovotney — Wed, 08 Jul 2026 04:46:16 GMT

Oh, You don't want to put down copper under the carbon to make a pot--makes sense. If you put exposed copper under the carbon, you will make a big press switch.

do this

put the carbon where the green is (non-copper) . Carbon only touches the copper at the end points( make sure to have no solder mask there). The dummy c71 (not installed), makes it look schematically like the nets are connected, but yet kept separated---so no errors