Skip to main content ↑ ↓
Topic: Drawing an internal slot with KiCad (Read 4125 times) previous topic - next topic

Drawing an internal slot with KiCad

Hi

I'm a designing a PCB with KiCad which requires internal slots to improve the HV isolation between tracks.

Is a single line, on the "Edge Cuts" layer (same layer as the board outline), of the slot thickness (width of the slot) good for the DirtyPCBs manufacturing process ?

Thanks for sharing your experience on this topic.

Re: Drawing an internal slot with KiCad

Reply #1 –
I've had panalised boards made successfully by dirtyPCB's, which involves a significant number of slots of various shapes cut in the board.

I guess this is equivalent to the slots you are considering.

I've designed the boards using Kicad.

I've defined those slots as 0.05 mm wide lines on edge cuts showing the boundary of the slots.

Remember there are minimum slot with restrictions on the design information, and that the slots will be milled in the board, and thus that radiused ends to the slots are easier to manufacture.

Advice from another supplier was that  panalisation slots are most economical at around 1.8 mm. Again your internal slots are probably comparable.

It may seem  counter intuitive that larger slots are cheaper to make, but the trade off is between the life of the cutter, the cutting speed and the amount of material removed. Very small routers are expensive, and wear quickly.


Harry

Re: Drawing an internal slot with KiCad

Reply #2 –
Thanks Harry for your reply

Quote
I've defined those slots as 0.05 mm wide lines on edge cuts showing the boundary of the slots.I've defined those slots as 0.05 mm wide lines on edge cuts showing the boundary of the slots.

I followed your advice and used a thin line to draw the boundaries of the internal slots, which are around 1.3 mm wide, instead of a single 1.3 mm thick line as I wanted to do at first. It clearly takes more time, but fortunately my slots are straight with no curbs ;-)

Quote
radiused ends to the slots are easier to manufacture

I used half-circles for each end of the slots, so it should be ok.

I only regret that the 3D view doesn't display these internal slots, but I maybe missed something ? Any idea ?

Rgds !

Re: Drawing an internal slot with KiCad

Reply #3 –
[attachment=0]

Kicad can show the internal slots correctly.

They have to form a continuous perimeter though else Kicad gives up and just guesses a rough board outline.

You have to draft quite carefully to ensure that all the shapes are closed. Especially at .05mm line width.


Harry

Re: Drawing an internal slot with KiCad

Reply #4 –
It may also be a version issue. I'm using:

Application: kicad
Version: 4.0.2-4+6225~38~ubuntu14.04.1-stable release build
wxWidgets: Version 3.0.2 (debug,wchar_t,compiler with C++ ABI 1002,GCC 4.8.4,wx containers,compatible with 2.8)
Platform: Linux 3.13.0-39-generic x86_64, 64 bit, Little endian, wxGTK
Boost version: 1.54.0
        USE_WX_GRAPHICS_CONTEXT=OFF
        USE_WX_OVERLAY=OFF
        KICAD_SCRIPTING=ON
        KICAD_SCRIPTING_MODULES=ON
        KICAD_SCRIPTING_WXPYTHON=ON
        USE_FP_LIB_TABLE=HARD_CODED_ON
        BUILD_GITHUB_PLUGIN=ON


Harry

Re: Drawing an internal slot with KiCad

Reply #5 –
Hi Harry

Thanks to you, I found what was wrong. For some reason, I had multiple duplicates of lines for the same slot. I probably ended tracing the lines with double-clicks instead of the 'End" key, and I had "polygons" instead of a single line.

Anyway, I deleted all of them by editing the pcb file (having a textual file is a so great), and redraw the slots very carefully ;-)

Everything is fine now.

Thanks again for your help !