View Full Version : what is post processing? Deskproto software, ambition of making 3d reliefs

20-01-2014, 05:57 PM
Please help. My quest to learn cnc from scratch without a tutor is making my head hurt. I'm sure the processes are quite simple once you understand them, but trying to de-mystify the process without a tutor is making my head hurt.

I am trying to get my head around the whole process from design to cutting. A phrase that keeps popping up is 'post-processing'. Obviously it's something that goes on after the CAM processing, but my question is - what is it and how does it concern me?

I have got a small CNC router (Exel 6090) controlled by DSP pendant. I am using Deskproto CAM software with the ambition of making 3d reliefs.

Can someone please explain to me whether post-processing is something that will happen automatically somewhere in my setup, or do I have to instruct it? Is it part of the CAM software or built into the router electronics somewhere? Or neither?

Is there a CNC beginners guide anywhere on this forum that would cover all the basic processes and choices?

I am not from an engineering or IT background and most of the manuals and guides assume a basic grasp of the processes. It's like trying to learn an instrument when you've never heard music before!

Thanks in advance.


20-01-2014, 06:30 PM
I'll start by saying I haven't used the DSP system - my DIY cnc uses PC control through Mach3 software and parallel port. But looking at the DSP system, and Deskproto CAM software I think your flow would look like this:

1. Draw object in CAD programme (didn't see and CAD ability in Deskproto) - create STL file
2. Use Deskproto CAM software to create the toolpaths (which tool to use, feed and speed, path to cut) and the related NC code (g-code) to create this path - This is the post processing bit
3. Import these NC text files into the DSP (via USB stick??? Not sure)
4. Run the programmes through the DSP to command the machine to move around and cut (I think)

I'm sure someone will come along with a more accurate flow . . . but the above suggests you will need a CAD program unless you are just cutting out existing STL files drawn by someone else.

20-01-2014, 06:32 PM

Every CNC machine uses G-code as the basic 'language' to tell it what to do. However few machines use G-code exactly the same due to 'interpretations' of the specification, think of them as dialects. Also some machines can do things in a more clever way, for instance, cutting an arc. Simple machines need the arc to be a series of small lines, clever ones just need to be told the start and end points and the radius and can work it out for themselves.

Post-processing takes the g-code from the CAM software and tweaks it for a specific machine, including adding headers that set up machine configurations.

For many simple machines driven by Mach3 controller no post-processing is needed

20-01-2014, 06:57 PM

Post-processing takes the g-code from the CAM software and tweaks it for a specific machine, including adding headers that set up machine configurations.

So I'm still a bit confused. Do CAM programs generally contain post-processors within them? Does mine? If not, should I be looking for a different one that does?

RouterCNC, I already have the design aspect (CAD) sorted thanks. It's the CAM to machining process that I'm now trying to comprehend. Not so easy when you're a bit hard of thinking with regard to computers.

I'm sure with the help of this forum I can start filling my workshop with dust and expletives soon enough.


Web Goblin
20-01-2014, 07:20 PM
A post processor transforms the machining file from your cam program to a language that your cnc machine can understand. This language may not only be G code as there are quite a few cnc machining languages and a few variations of g code. You need to get the correct post processor for your machine type so that it will understand the code.

20-01-2014, 07:23 PM
This web site might be worth a visit;
CNC Cookbook: Cookbook Articles (http://www.cnccookbook.com/CCCookbook.htm)

20-01-2014, 07:41 PM
Thanks guys. That cookbook website looks like just what I need.

So Deskproto has a list of machines in it's 'library' of which mine isn't one. The manual says to choose 'ISO G code in mm' as default if your machine isn't in the library. I'm hoping that this will allow Deskproto to 'post-process' the code so that my machine understands it. What do you reckon? Worth a try or am I missing a step?

20-01-2014, 07:55 PM
Take a look in your last posting you don't need to worry about Post P's save as the generic G-Code (mm) tap file