Software primer

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Forum topic by Mainiac Matt posted 12-27-2017 03:31 PM 1013 views 0 times favorited 8 replies Add to Favorites Watch
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Mainiac Matt

9561 posts in 3107 days

12-27-2017 03:31 PM

Topic tags/keywords: cnc software cad cam

This may have been done previously, but there are a lot of LJs getting bit buy the hobby laser bug, so I thought it might be helpful to provide a primer on the different software aspects to CNC machines.

1. create image: Artistic images are often done by the artistic crowd with a graphics program like Corel Draw or Adobe Illustrator, while the more techy types use CAD programs, such as Auto CAD (or the many free 2D drafting programs). This is the image you want to reproduce.

2. create tool path: This is the domain of the CAM software. For routers, it applies cutter compensation and will generate the tool paths needed to engrave lines, cut pockets or cut reliefs around your geometry. I’ve never worked with a laser, but have to assume there is some width to the burn and that the CAM software will apply the appropriate step over distance to burn an area. Most of the CAM packages I’ve worked with start with “vector geometry” (mathematical formulas to create the lines, arcs, etc…), however, many of the packages can also work with bit-map images (image defined by a grid of pixels), which it then converts into vector geometry tool paths. Once defined, the vector geometry tool path is converted into G-code, which is a sequence of text commands with a line of text G-code for each individual movement required to complete all of the tool path movements sequentially. While the CAM package will likely create a savable CAD file for the tool paths, G-code often has a .tap extension, they are simply asci txt files.

3. Post processor: This is analogous to a printer driver and it enables your CAM software to output the G-code in the format required by your particular machine. There are many, many machine makers out there, and to save $ and come up with some commonality, many will just use a format already defined by one of the big machine makers that paved the way decades ago.

4. Machine control software: This is the program that actually runs the CNC. It feeds signals to Home, Jog, and run programs. There are some different popular generic control software out there (Mach-3 for Windows, EMC for Linux, etc…). These generic machine control programs are customized for use with any particular manufactures CNC via. a plug-in that is usually and .XML extension.

This probably all sounds complicated, but many popular machines that are sold by big name retailers (Rockler, Woodcraft, etc…, that know they will be on the hook for supporting the customers) provide the machine with an all in one combo. package, that has some rudimentary 2D drafting capabilities, might be able to do some raster-vector conversion, and come all set up and configured to work seamlessly with the machine. People may balk at the price of these machines, and it’s definitely possible to build better for less, but what you’re getting is a plug and play package with the software all set up and ready to roll.

Our own Sir Stumpy Nubs did an episode highlighting how similar capacity CNCs can have significantly different prices, based on what they provide you for software. And as most of us know from our daily tap-a-tap-tapping… good software is a wonderful thing, and lousy software can drive you crazy.

The reason these China lasers are so cheap is that lasers have no cutting forces associated with them and the lower power laser modules are pretty light weight, so they can make them with scanty frame construction and they don’t really provide anything at all by way of software or support. They’re fun for hobby peeps, who are happy to spend hours setting them up, as that’s all part of the fun.

-- Matt -- I yam what I yam and that's all what I yam

8 replies so far

View Monte Pittman's profile

Monte Pittman

30552 posts in 3116 days

#1 posted 12-27-2017 03:46 PM

Thanks for the info sir

-- Nature created it, I just assemble it.

View boxcarmarty's profile


17340 posts in 3138 days

#2 posted 12-28-2017 01:40 AM

Yep, that about sums it up…..

-- My mind is like lighting, one brilliant flash, then its gone.....

View Greg the Cajun Wood Artist's profile

Greg the Cajun Wood Artist

515 posts in 1721 days

#3 posted 12-28-2017 01:47 AM

I read what you wrote and didn’t understand a word. I am utterly confused with cnc computer stuff. It is a bummer because i would like to get one and try to figure it out…but it would likely become an expensive paperweight.
I gave up trying to figure sketchup

-- Wood for projects is like a good Fart..."better when you cut it yourself" Don't take yourself so seriously. No one else does

View DS's profile


3503 posts in 3199 days

#4 posted 12-28-2017 04:30 PM

That is a good summary Matt.

In all fairness to Greg, though, it should be said that #3 and #4 are usually set up one time when you first set up your cnc machine (and likely set up by your machine vendor, or manufacturer) and not thought about much after that.

If you DIY your own machine, #3 and #4 could be more challenging, but again, done just once. (unless you make physical changes to your machine)

So, mostly, creative drafting (#1) and tool paths (#2) are what you would be concerned about.

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View sawdustjunkie's profile


409 posts in 2495 days

#5 posted 12-28-2017 04:43 PM

I never could figure out Sketchup, but a CNC is different. Not as hard to learn the software, if you have ever used a computer before. Thousands of Youtube videos to watch and learn. I have had a CNC machine for about a year now and have made hundreds of projects.
One thing to note however is all cnc machines are not created eaqual. I had a Next Wave HD4 for 3 months and wound up taking it back because of so many problems. The Shark forum will back that up with lots of users complaining about that machine.
I wound up getting a Axiom for a little more money and the thing is built like a tank.
Hope this helps with some answers.

-- Steve: Franklin, WI

View ArtMann's profile


1480 posts in 1594 days

#6 posted 12-28-2017 04:51 PM

For people who are unaccustomed to machine controlled motion, the learning curve can be pretty steep. I recommend the Vectric software products without reservation. They are simple to learn, provide a lot of power and flexibility and are economical in comparison to the alternatives.

View Mainiac Matt 's profile

Mainiac Matt

9561 posts in 3107 days

#7 posted 12-28-2017 08:58 PM

I personally am not a Sketchup fan for a couple reasons:

1.) I find the user interface to be awkward as it’s not much like any of tghe CAD programs that have been around for decades. Once you learn one CAD program, learning another is really easy, as they all function pretty much the same.

2.) Sketchup is more closely akin to the graphic arts and 3D animation worlds as it uses a “mesh” of little triangles to make the 3D images. While the 3D modeling programs used for engineering type work use sophisticated mathematical modeling called NURBS to create curvy surfaces. And while you can get higher resolution with your mesh by using smaller and smaller triangles, you can always zoom in more and see the disjointed surfaces. With NURBS, you can zoom in more and more and the software just re-calculates and presents you with a smooth surface.

3.) Skechup doesn’t play well with the other children. Despite some apps that boast conversion and the ability of Sketchup Pro to save in a format that then can be opened by “real” modeling software, the reality is that mesh is mesh and NURBS is NURBS and the two are fundamentally different and you can’t truly be convert from one to the other. I’m not even sure if tool paths can be generated from a Sketchup file, as I’ve never seen their file extension listed as a compatible file in any CAM package.

Sketch up, imho, has one (and only one) thing going for it. It’s free.

-- Matt -- I yam what I yam and that's all what I yam

View oldnovice's profile


7563 posts in 4146 days

#8 posted 01-06-2018 09:05 PM

I am in the same boat with Matt as I have never been enamoured with Sketchup even though many have. I believe it was due to my use of CAD for many years before Sketchup was available.
My first exposure to CAD was the GE Calma system (~1982) and, then much later startinng with a new employer, I was trained on One Space, originally from Hewlett-Packard and later bought by Parametric Technology Corporation. In 2002 a free, reduced feature set version, of Creo Elements/Direct Modeling Express was made available and I have used that since then. Creo Elements/Direct Modeling Express is a decent 3D CAD package, in my opinion better than Sketchup, but it has been nearly stagnant since 2002.

However, I am now in the process of learning Fusion 360 from Autodesk, a complete package from 3D CAD, sculpting, CAM, 2D drawings, rendering, and probably more to come. There are many tutorials on YouTube and a lot of books available to learn how to use Fusion 360 making it fairly easy to learn. I will probably never become an expert in Fusion 360 but I will learn enough (to be dangerous) to do what I want for my shop work! Having CAM as part of Fusion 360 is definitely a benefit as it greatly reduces the effort to start cutting!

-- "It's fine in practise but it will never work in theory"

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