Living with CAD-CAM today

Created by: Lester Caine, Last modification: 13 Oct 2014 (10:56 UTC)

Where does all the time go ...

I'm trying to get some some of the scraps of paper which have formed the documentation for the MEDW products on to the computer but with some of my tools getting a bit long in the tooth, and spread between Linux and Windows is not helping.

CAD goes back to early AutoCAD days and I still have the 2.5 dongle around somewhere, but my PCB tools even pre-date that, with Racal-Redac being my first purchase which ran on a £5500 IBM AT many years ago. It paid for itself with the number of boards being laid out at that time and the price bureaus were charging for even taped layouts at that time. Anybody still using red and blue tape to lay out two sided boards?

PCB stuff moved on to PADS and the follow on to that, but cost of upgrades was more than the cost of getting boards laid out by others, so I stopped that railroad, but I do now have an older copy of EasyPC these days but even it's very low upgrade costs need justifying. With KiCAD offering an alternative if only I could simply copy existing material across but with project files tending to be proprietary.

The CAD files are a lot easier with DXF and even the modelling file formats being a standard, but this still needs a bit more work to be transparently transferable. A lot of the earlier AutoCAD material simply works with TurboCAD but still having 15.1Pro, later versions of DXF files can be a problem unless saved to something earlier. IGES files seem a little more stable, but come with other problems.

So just what is the best way forward? Most of the jobs I am doing start with a printed circuit board, and the project gallery is a very typical example of how things go together. The button layout on the front panel are defined directly by the position of those buttons on the PCB. EasyPC provides a DXF output which can be used for the machining drawings, and in theory provides a 3D model which still needs some additional work to add missing component models. Using bitmaps of the screen layouts are normally OK on the assembly drawings for now, but ideally this hole will be filled.

Since the boxes need machining, 2D drawings which can be used to generate GCode are the second step anyway, Currently this is processed via vCarve to produce the relevant files.

These two elements are combined currently using TurboCAD which also provide a 3D modelling facility, and the images on the website are taken from that package. This is all functional and does a more than adequate job, but the problem is it's all on Windows and my main desktop is on Linux ...

LibreOffice works transparently between the two, and the spreadsheet provides management of the project costing, but even that is not ideal since copying bill of materials from the PCB package is not tidy, and every part needs supplier part numbers adding and prices. It was this area that first prompted the interest in 3D models which are starting to become available from the various manufacturers. Initially for the EasyPC package, but those are not readily available and would not be usable in other modelling tools so an alternative approach is obviously needed.

Which is where I am today ...
KiCAD and LibreCAD were an obvious starting point, but FreeCAD should provide a better base platform especially since it is extendible using Python. Not my first choice for scripting, but something I already use on the coding side with Mercurial DVCS and a few other tools. The problem with FreeCAD is it introduces another way of modelling which needs a different approach to building components to that provided by the manufacturers.

Watch this space ...