Using Open Source and CNC?

blueZ3 asks: "I am thinking about purchasing a CNC (Computer Numerically Controlled) milling machine to build small parts to support my hobbies. I'm looking at a machine from Tormach or CNC Masters. These are small, hobby-class CNC mills. Even though I've picked low-cost machines that look interesting, they all require software that adds significantly to the cost of the machine. I've worked with proprietary CAD software before (TurboCAD, AutoCAD) so drawing parts isn't a big deal. But I'd like to avoid spending huge amounts of money on software, when I'm already breaking the bank for the mill. Does anyone out there have experience using Open Source software for CAD that has a relatively 'normal' GUI/interface? Is there a 'mature' CAM conversion software for same? Does anyone want to comment on the intersection of Open Source and CNC?"

Comments

At least you can save the price of the OS

[the_illuminatus]

Weber Systems makes a cad/cam package that runs on Linux. In fact, their windows versions use cygwin! Some of the system is written in bash, and you can at least try it out for a while. http://www.webersys.com/linuxsynergy.htm

Re:At least you can save the price of the OS

[Directrix1]

Has anybody checked out the open source BRL-CAD before? Apparently its pretty mature, and the military uses it.

Build Your Own

[MBCook]

If you have some tools, you can build your own quite cheap and make a great machine. A guy named John C. Kleinbauer sells plans on his website for a couple of different machines. Once you buy plans, you get access to his "inner circle" BBS (can't remember the name) where he personally supports his plans, he and other members talk about their machines, what they are building, tips, etc.

It's a great little community.

By going this way you can save cash on the machine to buy the software, but they also mention software you can use that is either cheap or free.

Re:Build Your Own

[Phronesis]

The point of CNC machining is precision down to the tenth or half-tenth thousand.

That's just not true. I do a lot of CNC at 0.005" or coarser tolerances. CNC is also great for turning out lots of repetitive work (drilling and tapping thousands of holes for optical breadboards, turning out dozens of widgets). CNC is also good for complex curves. On the other hand, if I'm machinging rectalinear or circular surfaces and want 0.00001" tolerances, I can do as well by hand with a good solid machine. That way, I can set up compound slides to give me good precision and measure between each cut.

Just because some CNC machines are good for some high-precision work doesn't mean either that CNC is the best way to do any precision job or that CNC is only valuable for doing precision work. CNC can be hugely useful for some loose-tolerance work and some high-tolerance work is better done manually. It's often a question of whether it's faster to create and check the routing code or to cut manually.

BRL-CAD?

[LWATCDR]

http://brlcad.org/
I don't know if it will export IGES but it might. If not Turbocad is pretty cheap.

http://www.linuxcnc.org/

[RGRistroph]

Not for designing the parts, but for controlling the machine during the run:

http://www.linuxcnc.org/

http://www.opencascade.org/

[ghinckley68]

http://www.opencascade.org/ should do all you need open source. Has some rather high system requirments but it seems to be a good program.

GPL CAD/CAM

[Donat]

I have been doing CNC work for a few years now, mostly freelance. Drawing tool paths for business signs, reproducing parts for farm equipment, some wood craft items and writing software to do the simple stuff; generating and post processing g-code and talking to controllers.
You might want to check out QCad, it is GPL'd CAD/CAM software with g-code support and it only costs a few hundred dollars.
http://www.ribbonsoft.com/qcad.html
(no affiliation)

Options

[peu]

For the numeric control part of your CNC machine you can use the EMC (linuxcnc.com) which is opensource, or you can use Mach3 (artofcnc.com) wich is the paid and much improved version of it for a mere $150, you will receive in support many, MANY times that amount in the 1st months.

Regarding CAM, there are simple converters from vector art to G-Code such as ACE Converter (http://www.dakeng.com/ace.html).

For CAD you got the ad supported version of alibre (alibre.com)

And my last recommendation, goto: cnczone.com and read for hours, there are tons of knowledge there on every aspect of CNC.

BTW, if you are on a short budget, why not build the machine yourself and save some money for an entry level CAM app?

I have the perfect solution!

[iq in binary]

YOU are a cad/cam program my friend. CNC machines are controlled by a universal machine programming language called G/M code.

It's also probably the simplest script language known to man. Learn how to use it yourself instead of spending several thousand dollars on a CAD/CAM program.

Here's an example of your typical part program for a CNC machine:

G72G81G90G91

G0T1M06

S1200M03

X0Y0Z.1M08

G83X0Z.5Z.1Z.1

G0Z3.0

G0M22

That program just drilled a hole .4 inches deep into the center of a circular part. Fairly simple, neh?

Re:I have the perfect solution!

[Degrees]

And interestingly enough, that language isn't very different from Scalable Vector Graphics (SVG) - although SVG is 'defined' for 2D, with the 3D extensions still in 'experimental' form (last I checked).