Hi all, i really dont know anything about how cnc works. The only thing i think i know is that you have to bring your 3d model from MoI to a cam package or something like that. So the question is what does that cam thing do? and what cam you know and recommend me that plays well with MoI.

A CAm package will help you generate a "toolpath" for a particular geometry object.. It can be 2d, 3d or "non of the above".

Here is a screenshot of some toolpaths (The green lines):



The program will then generate "GCODE" which is what the machine controller reads to move the motors on your machine:

N01 G20 G40 G49 G54 G80 G90 G91.1
N02 G54

(.5 ENDMILL ROUGH T 1)

N03 T1 M06
N04 S374 M03
N05 G00 G43 H1 Z1.1 M08
N06 G90 G54 X-.93 Y.3671
N07 G01 Z.4998 F.8984
N08 Y.3161 Z.5226 F1.4973
N09 Y.2776 Z.5375
N10 Y.2669 Z.5413
N11 Y.2192 Z.5555
N12 Y.1733 Z.5665
N13 Y.1287 Z.5749
N14 Y.0852 Z.5807
N15 Y.0426 Z.5841
N16 Y.0006 Z.5852
N17 Y-.0409 Z.5842
N18 Y-.0835 Z.5809


The CAM package will need to generate the types of toolpaths you are looking for, on the types of entities, and also be able to output gcode to match your machine controller.. (They all speak a slightly different language) Also, the ability to customize this code output is good too, for personal configuration.

There's a start!

Hi Ed17.

For the most part, any decent CAM package will work with Moi. Nearly every one available will properly import an STL file and convert it to CNC data. The trick is to design with CNC in mind, so you don't end up with radii that cannot be duplicated with the available tools. For example, if your smallest bit is a .003" ball mill, then all the curves in your design must be that size or larger. Otherwise, some odd compromises will happen during the CNC operation. Luckily, if your tolerances for fit and finish are relatively "loose", the problem should not really present itself.

Moi actually generates *EXCELLENT* STL meshes for use in rapid prototyping and CNC operations. I am often asked what version of SolidWorks I am running by my vendors. They are more than slightly surprised when I tell them I am running Moi exclusively.

Confused yet? LOL

Chris

""""""""""Moi actually generates *EXCELLENT* STL meshes for use in rapid prototyping and CNC operations.""""""""""""

Industry best!!!!!!!!!!

Are you guys aware of any free (or low cost) STL to G-Code converters?

I just want to try a "proof of concept" using a MoI model on my mill (with Mach3 controller) before buying an expensive program.

Ed

Hi Ed,

> Are you guys aware of any free (or low cost) STL to G-Code converters?

Here's one: http://www.mecsoft.com/freemill.shtml

It says it imports both STL and 3DM, but based on the other import formats it may only support polygon mesh data in the 3DM file, so the 3DM import may not work for you, but STL should.

- Michael

Hi Ed,
I could generate some code from a model for you to load in Mach 3 if you want... If you post a model, and specify some tooling/cutting parameters, I'll generate the code for you to load and cut, and look at.....

Thanks for your generous offer BurrMan.

I downloaded FreeMILL as Michael suggested and will give it a try.

So many toys, so little time .....

UPDATE: Dang - it doesn't handle 4th (rotary) axis.

Ed

Hi Ed,

I'd seriously doubt you'll find anything for free that'll support 4th Axis Rotary..!
But one of the cheaper options would have to be DeskProto.
http://www.deskproto.com/

HTH, Colin

I always check what Sourceforge has to offer http://sourceforge.net/search/?q=cnc , I don't know how good these programs are and I haven't the time to play with them but it's worth a shot if you're on a budget or have no budget at all :)

'Generic CAM' looks interesting you can define up to 9 axis' http://sourceforge.net/projects/genericcam/

Cheers

I would say with many options to look at, the main thing you want to pay attention to when deciding (Well first is can it create the toolpath I want), is that the program can output the gcode for your mach3 to read... They all arent created equal...

So, is the code output customizable and to what degree? (You could ignore this part if you are capable of hand editing)

CamBam will do a great job with 2D dxf's and stl files from MoI.
I use it for mould work quite a lot.

It doesn't have 4th axis capability, but there is another program called CNCWrapper that will convert either the X or Y coordinates to rotary. Note that it isn't a TRUE representation of rotary like you'd get with dedicated software, but it's still very good.

CamBam is fully functional with 40 trials before it reverts to only producing ~500 lines of gcode, so if you leave it minimised to the Taskbar you've got plenty of time to get the feel of how it works.

Martin.

Thanks for all your answers! I understand a little bit more now!

the new inkscape support Gcode ;)
http://www.cnc-club.ru/forum/viewtopic.php?f=33&t=35&start=20