Using DXF Files as CNC Control Input

      The latest generation of CNC control software can accept some AutoCAD-generated DXF-format files directly and use them to cut parts, without the need for secondary processing by a post-processor. January 27, 2008

I have been cutting a lot of DXF's on our Thermwood with an updated version of control nesting. The process is pretty straightforward:
- Import file to cad
- Save as version 12 (DXF)
- apply layer names
- ensure all geometry is closed
- cut parts

Initially the learning curve is pretty steep, however now I have even learned to use the layer translator to speed up the process. Is this process similar to other CNC routers? Can most CNCs cut cab parts directly from an AutoCAD file using a DXF?

Forum Responses
(CNC Forum)
From contributor S:
It's not possible for you to be "cutting DXF's on a CNC." A DXF is a computer file composed of binary digits.

From the original questioner:
Excuse me... We are using DXF's to cut cabinet parts on the router (usually out of some kind of sheet good).

From contributor L:
DXF files are actually text files. Once you learn the keys, you can actually read them and work out what they are doing.

From contributor S:
You are correct - a DXF file is in fact a text file. I was thinking of computer files in general. I stand corrected.

From contributor M:
To answer the original question... Yes. The process of using DXF files to generate your G-code has been around for more than a decade now. Most CNC manufacturers now offer this with their machines and there are a lot of third party post-processors that offer translators to most makes of CNC machines.

To try and clear up the secondary discussion in this thread, the DXF files only provide the geometry. You still need a post processor to translate that information into the G-code appropriate for your machine. Somewhere along the way it has be told how to interpret that information, be it by layer name, color, or some other method. Simply put, the DXF file itself is not enough to make the machine produce a part.

From contributor K:
Thermwood has simplified this process by eliminating the need for a post processor. Here is a quote from their website about the Generation 2 control.

"Control can accept raw design files in addition to CNC programs - First generation controls are primarily playback devices, much like a player piano. They require that the programmer not only design the part but also perform a series of additional functions including CAM, nesting, and post processing in order to generate a precisely formatted program that the control can execute. Next generation controls such as Thermwood’s Gen2 SuperControl can, in addition to standard CNC programs, also accept raw design files directly from design software without the additional processing. It automatically performs any program preparation necessary to machine the part.

Control is directly compatible with virtually all design software - DXF files from any CAD or design software can be sent directly to a Gen2 SuperControl.

Combine files from multiple software sources in a nest - The control creates nests of parts internally and can combine parts from multiple sources in the same nest.

A single job file can contain hundreds of parts rather than requiring hundreds of separate CNC programs for a job - Including all the parts for a job in a single file can dramatically reduce file handling and improve productivity of the machine. The control nests the parts on the appropriate material, tells the operator how many sheets of material are needed for the job and tells him what material to load. In fact, it guides him through the entire process, step by step. This file also contains information for machining the back or flip side of certain parts. It prints a label for each part. Parts that require flip operations have a bar code on the label. When the operator scans the bar code, it identifies the part to the control which automatically retrieves the correct program. From the operator’s standpoint the whole process is simple, load one file and follow instructions. In a first generation control, the CNC programs are developed outside the control, so there is a program file for each sheet of material in the job and yet another program file for each flip operation. These files are normally processed into individual CNC programs. A single job may require a hundred files or more that must be sent individually to the machine. Some really limited controls may only allow one, or maybe a couple of programs to be loaded at a time. An operator then needs to sort through, identify, handle and load hundreds of files each day. This takes time and reduces productivity of a major investment, the CNC router. Also, this approach is more prone to error."

From contributor A:
Contributor M, that is the answer I was looking for myself. I have a Mastercam version 9 sute that I would like to link to the resident software in my Masterwood ptp (Masterworks). I talked to a Mastercam rep at the recent Vegas show about a post processor to make it work and he said there wasn't anything available. It is hard to understand because Masterworks is being used in the latest Masterwood machines. I e-mailed Masterwood but they are out for the month.

Any suggestions where to call? The Mastercam rep I talked to seemed uninterested. My interest in the Mastercam software comes from the fact that a neighboring machine shop uses it and the guy who runs it is willing to train me, which is a huge advantage. I came through the software through a third party.

From contributor M:
Contributor K, after digesting your response, the only thing Thermwood has done is to eliminate the middle man (post processor) from the equation. This still mandates a properly formatted file with all the elements on proper layers, and somewhere along the way there has to be a set of rules defined to tell the machine how to interpret the info you are feeding it (sounds like a built in post to me). What happens if you feed it a 2D dxf file? You will still need some manual intervention to tell it how thick your piece is. In addition to that, how does the machine distinguish the difference between brad point and through point bits?

Contributor A, I am relatively new to MasterCam and have only used MCam X. But you might try calling ShopWare (they are one of the top MasterCam Dealers). They might have a post available for your machine.

From the original questioner:
First things first... Using DXF format is by no means a substitute for Mastercam (going to training this month), Microvellum (I use daily) or e-cabinets (use daily). However I regularly (daily) receive emails with fairly simple geometric shapes (radiuses, basket handle arches, ellipses, etc.) that need to be cut on the CNC. Rather than open up any other software, I simply double click on the attachment and proceed as I explained in my first post... Very straightforward.

As far as what tools are being used, there are several options.

1. Like most programs, we have material groups set up on the router (that use specific tools). If cutting S/surface, we simply load up the DXF and choose S/surface. The router does the rest...

2. In the layer name, we can designate the diameter of tool we want to use. This, combined with preloaded material files, allows us a great degree of control with very little effort.

The bottom line is we receive AutoCAD files and can usually cut them directly off of the customers file - very little manipulation on our end means more cutting and less time programming (this equals more money).

As a closing note, like I suspected, Thermwood has really got their act together with this one... a simple process is still simple... no middle man required.

From contributor K:
I recently read an article that tells a little bit more about the "Next Generation Controls." What I get from it is that it will be a great benefit for shops that cut parts for other shops. They can now accept design drawings from most any cabinet design software and be able to nest those parts easily with fewer mistakes. They will get the same ease of operation from other design software that they get using eCabinet Systems Software. This will also be beneficial to shops that already use a certain design software that are interested in a Thermwood router but don't want to change design software. They can send jobs from their existing software without all the post processors, or they can use one software that does kitchen boxes quickly to do that work and use eCabinet Systems Software for the more complex parts in the job and easily send both to the same router without problems.

From the original questioner:
I read that article, and that is exactly what we do. If the part is designed in A/cad, we format it appropriately and cut it. We do the same with Microvellum. Unfortunately, all software packages do not output DXF's in the same manner and formatting (closing lines, deleting segments, etc.) can take a little time. But other than that, it does work pretty much the way the article said.

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