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The Shop => Software Tools => Topic started by: John Hill on February 06, 2015, 03:23:35 AM

Title: Starting at the beginning!
Post by: John Hill on February 06, 2015, 03:23:35 AM
I am building my CNC router table and have LinuxCNC installed and driving steppers that are at present mounted on a piece of wood.

I also installed FreeCAD on another Linux machine.  Both are Ubuntu OS.

Now then, there are a few gaps in my understanding!!! FreeCAD draws 3D objects and LinuxCNC can (or will be able to) drive my router table, but surely there is something missing in middle?

Also, I presume if I just want to cut out a few shapes I can just write some G-codes in a file and let LinuxCNC get to work?  There must be aids to do this so what should I be looking for?

There is a big, very steep, learning 'mountain'   right in front of me!
Title: Re: Starting at the beginning!
Post by: philf on February 06, 2015, 04:06:56 AM

Now then, there are a few gaps in my understanding!!! FreeCAD draws 3D objects and LinuxCNC can (or will be able to) drive my router table, but surely there is something missing in middle?

Also, I presume if I just want to cut out a few shapes I can just write some G-codes in a file and let LinuxCNC get to work?  There must be aids to do this so what should I be looking for?

There is a big, very steep, learning 'mountain'   right in front of me!

John,

The missing link is a CAM program.

If you want true 3d CAM then I don't know of a free version or if there any Linux versions. For Windows there are a few "budget" 3d CAM offerings. Vectric Cut3d, CamBam, MeshCam, DeskProto are typical but expect to pay a few 100s!

I don't know a lot about top end 3d packages but the ones I've tried are incredibly slow and seem to take a lot of time cutting thin air.

More common is a 2.5d program. The .5 axis is the Z axis and Z moves are separate to the X & Y. Thus you can e.g. machine a pocket to a fixed depth but not put a slope on the floor of that pocket. I use Vectric Cut2d which isn't too expensive.

I'd love to know of a cheap 3d package

Much can be done by writing the G-Code manually but not for a complex 3d part.

I hope someone else will come up with a solution for you.

Cheers

Phil
Title: Re: Starting at the beginning!
Post by: David Jupp on February 06, 2015, 09:46:20 AM
PyCAM is open source and available for Linux.

No idea how good it is - like much Linux software I get put off by all the hoops it is necessary to jump through.
Title: Re: Starting at the beginning!
Post by: vtsteam on February 06, 2015, 12:26:32 PM
I use free Sketchup 7 for 3D design and free SketchuCAM add-on to generate the G-code. These are Windows programs but they run in WINE under Linux.

SketchUCam is 2.5D not 3D so far (when I last checked) but is under continual development and improvement. It's located at the Phlatboyz site.

I believe there are limited but free versions of CamBam, and those are I believe true 3D, but I haven't tried them yet under WINE in linux. I believe they will work, though.
Title: Re: Starting at the beginning!
Post by: RotarySMP on February 06, 2015, 01:39:08 PM
To get started, you can draw your toolpath as a polyline in Freecad and save it as a DXF file, and then use the share program DXF2gcode to convert them.

http://code.google.com/p/dxf2gcode/

You can edit to final code to add your Z axis moves by hand. G-CODE files are simple text files so you can edit them in wordpad or Gredit in Linux.

You can also use EXCEL for writting g-code of geometry shapes.

Mark
Title: Re: Starting at the beginning!
Post by: John Hill on February 06, 2015, 02:48:49 PM
Thanks for the comments...

I am thinking that I should ensure my machine is capable of 3D,  I actually have drivers for five axis two of which are 3 phase.  I will be using one of the 3 phase drivers to drive my washing machine 'stepper' for the long X axis.  As far as I can see being '3D ready' just requires that I have a controllable Z axis and a usable clearance under the gantry.

Mark, I think you have filled in my missing link with DXG2gcode! Thanks. :thumbup:

Of course I dont have to stay with Linux but I thought I would give it a try (yet another part of this project that I, so far, know nothing about!)  Steve, I see a number of references to people using CamBam. :coffee:

Most of the work will be basic cutting of sheet materials, ply and MDF etc,  and probably making a few wooden signs for farm gates etc.

Meanwhile, back to the workshop...
Title: Re: Starting at the beginning!
Post by: vtsteam on February 06, 2015, 02:55:49 PM
John, 5 axes, wow! Cool. Anyway, sounds like most of what you plan now will be satisfied with 2 to 2.5. And 3 is available in free, or low cost, software. If you eventually do go to 5 axes, though, I think you'll need very sophisticated CAM software to generate the moves.
Title: Re: Starting at the beginning!
Post by: John Hill on February 06, 2015, 10:12:57 PM
Steve, I dont expect to be going to 5 axis on this router table but maybe I will fit steppers etc to my mill or lathe some time in the future.