Getting your gerbers right. PCB design chat, prius related too

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whereswally606
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Location: Cheshire, UK

Getting your gerbers right. PCB design chat, prius related too

Post by whereswally606 » Jan 10, 2018 7:04 am

WARNING LONG SLIGHTLY GEEKY POST
So recently I've learnt a lot about how to manipulate Gerber files directly and indirectly to change designs or to get the format such that you can use your preferred cheaper fabrication house.

This has been partly through having to redesign bobc lebowksi brain board to work around chip shortages, which was indirect since I could change the footprint of the part in Kicad and the reprint all the Gerbers and send them off for production.

And more recently the indirect. That has been I have been trying to reverse a design from the now defunct hybridinterfaces.ca which was originally designed using pcbExpress and thus ordering the PCB had to be done through them at quite a high cost. The PCB is for a device called the BMS2 which is the successor to the BMS+ which was designed by a chap called Norm who has basically made it possible to spoof the ah of the battery in a prius. This twinned with the ability to drive a 2nd gen prius in ev only mode under 85kph/50mph (gas empty OEM mode tricked via a switch) has allowed a French chap named planetaire to build a 129mile capable EV only miles Prius (which a large amount of a123 and lifepo4 batteries added in)

I hope to replicate this in the next 6 months or so and was putting in some ground work to make the device more cheaply. I think after a week of tinkering and learning that I have managed to get something PCBWAY will accept and I can have 5 made for $42 which is better than 4 for $160 from pcbExpress.

Anyway I've learnt a lot from a range of places.
some of which is here
https://priuschat.com/threads/hybrid-in ... 678/page-2

So I took the original design and used the print in photo etch mode.
the overhanging silk screen on the left hand side causes mis-alignment so I ungrouped and deleted any overhangs before printing.
I printed using an Epsom postscript printer which produces .prn files

These prn files I used linkcad 9 to convert to gbr files (but my trial license ran out after 5 days)

The drill Gerber file was harder to make. This required a lot of ungrouping of the parts on the silk to get the pads and only the pads. Next I printed just the pads to a prn file. using Linkcad 9, I converted to a dxf file and opened in Inkscape 0.92 (a brilliant app) Then I used Inkscape to tidy up the holes and delete any silkscreen bits. Then I saved the dxf and converted it back to gbr.

Also for this I used gerbV.exe (not gerbView they aren't the same) to move and realign the drill Gerber file with the copper layers

My Linkcad 9 license ran out and I looked for an alternative for the conversion process from prn to gbr file, Linkcad 9 is about $500 a license. I found reaConverter, their standard trial can do much the same work and lasts for 15 days. Knowing that this would run out too and a reaConverter license is $49, I wanted a completely free way so I kept searching. By this time I had managed to create the copper layers, the drill layers, the silk and two mask layers, so I have something uploaded to the above priuschat forum that will pass audit at pcbway. (use at your own risk it is completely untested) That is to say at this point its more of a challenge to see if it is possible and for any future work I need to do in this area.

So I hunted the interwebs also found pstoedit.exe and gsview5.exe

gsView 5 is kinda a GUI for psToEdit.exe and for somethings it works but it does crash which made me focus on getting the cmd line psToEdit conversion working without gsView5.

Unfortunately psToEdit produces old D type Gerbers not the newer X format with embedded aperture files.
so you can not really use it to produce useful Gerbers directly. However It does produce good dxf files which can then be tweaked in Inkscape 0.92 and the another brilliant find was dxf2gbr.py on sourceforge which then can take a dxf and make a Gerber X format file.

n.b.
dxf2gbr.py requires python2.7 and has 3 other dependencies but they are gettable and it does work if you follow the how to.
https://sourceforge.net/projects/dxf2gb ... rce=navbar

Anyway that's it for now, hope this info helps other here.
Distributing "Lebowski" FOC Controller PCB (Through hole) since 2016
Moped: Emax 110s 2009

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