FreeCAD CAD/CAM/FEM/Ships/Robots/


#1

Any FreeCAD users around?

I looked at it a before I had done any 3D printing or CNCing and was totally lost, never got started.

Now with half an idea about both processes and a need to do some tricky CNC undercuts that pycam, Inkscape, OpenSCAD and NativeCAM etc cannot handle, I have made a OKish spreadsheet to generate gcode for undercuts, but it does not cater well for variations in stepdown and minimising tool changes etc.

Another big capability is a large range of ex/import file types, including abiility to edit imported files, which also has been a big restriction for me in above tools.

In addition with the donation of the CNC lathe, being able to do full 3D designs and especially have a large degree of control over how the gcode/paths are generated is really desirable, so I have started learning FreeCAD.

So far baby steps for me, but have managed to do a fully parameterised and constrained 2D design, so have hope of getting much further!

Anyone else using FreeCAD? Want to swap tips & how to’s?

Anyone want to learn? I can at least show a couple of the key features (stumbling blocks!) that give a solid start to using FreeCAD.


(Stephen Davies) #2

Hi Spencer,
Have been thinking we should probably have a CNC software bake off. I’m halfway through the free trial period for cambam. Like the software but am interested to see if any of the freebies offer similar functionality and ease of use.


#3

Great idea.

In a way bit like what I have been going through trying to find better tools.

However is the biggest challenge setting the bakeoff rules? For me, while $A200 license is affordable, can’t help think how many end mills etc I would miss out on! Plus been trying hard to mainly use/support opensource and cross platform, so I usually end up choosing different sw to many.

Of course plenty of extra challenges going that route, for example have crashed FreeCAD 3 times already.

Where dp you stand on parametric models and scripting/macros?

I am also pretty keen on fewest number tools ie design to path/gcode and maybe also gcode sender.

What are your thoughts on these and other requirements?


(Stephen Davies) #4

Hi,
imagine this is discussed frequently on sites like cnczone.com. Rules is possibly too strict a term, maybe criteria?

Things like:

  • Price
  • 2D/3D
  • Import/Export capability e.g. .dxf, .svg etc.
  • tool path quality/optimisation
  • tool library support (i.e. define cutter geometry once, can reuse between projects)
  • mouse vs keypad entry (see below)

Watched a Ben Heck video early on, he suggested Inkscape as a CAD equivalent then import SVG into the jscut.org web page to generate the gcode. There were a couple of things I didn’t like about this approach. The main problem was that jscut doesn’t handle SVG objects (circle, rectangle etc.), it just wants SVG paths (assume line segments). Once you’ve drawn things in Inkscape you have to select all objects and convert them to paths. More than an annoyance because you’ve converted the model to an approximation (esp. arcs).

Early on I needed a gcode program to flatten the mill table and engrave a grid on it. I wrote a small Java library and a couple of programs that would perform basic graphics primitive type operations, e.g. lineTo, that would generate gcode. This worked well although I could have put a little more effort into improving the toolpaths.

Tried using Libre CAD as a CAD drawing tool producing a DXF that I then imported into CamBam. This worked ok but found that small changes to the drawing would blow away the CAM model so eventually settled on using CamBam for both the drawing (CAD) and machining (CAM) stages. Would point out that most of my work to date has been simple parts i.e. 2.5D type work.

One thing I really like about Libre CAD is the modal console for data entry. You can enter a command like ‘ci’ (circle) and then just enter the centre and diameter (or radius) using the numeric keypad. No mouse clicking or dragging followed by the inevitable manual cleanup because you were 0.163491 of a mm off.

I’d suggest omitting the gcode sender as this is often coupled with the CNC controller board. I’m using Chilipeppr because 1) it supports the Tinyg and GRBL boards and 2) has excellent Eagle PCB support.