I thought it would be a good idea to try some of these DXF files download sites myself. The first site I tried was 3axis.
The Review Process
I found two different CNC Router DFX files to download and test with the Vectric Aspire CAD/CAM software. This software is what I use and have licensed. This exercise aims to show the quality of the DXF files, not how to use Aspire.
Typically, if you have problems with your DXF files download, it will be in your CAD/CAM software. The vectors will overlap, be duplicated, or have some other issues. You must fix these issues before creating tool paths that you can upload to your CNC machine for milling.
You can fix different problems with vectors, but it's generally a manual process and takes some time. How long to spend on it is a judgment call on your part - whether you see the value or not. Many professionals in the industry would hire this part or probably design their Vectors.
Wooden Chopping Board Design Vegetables
I first chose a Wooden Chopping Board Design with different kinds of vegetables. It's simple but should also have a good deal of Vectors so we can examine their quality. The file download process here was simple, click the download button.
After one more screen with another download button, it downloaded as a DXF. No compressed files to deal with in this case.
I started my Vectric Aspire software, created a new document, and imported this new DXF file. After that, the software imported the vectors without any issues.
The Vectors were off-center. Pressing F9 in Aspire automatically centers the selected vectors on your material.
A common problem with DXF files is the number of nodes or points which make up the vector. I've enabled the node editor in one of the carrot vectors below. There are so many nodes it looks more like a black, thick line. However, each of those little black squares is a node a requires a sequence of g-code in the file uploaded to your CNC machine.
The problem with this is that it sometimes slows your machine down. It can also cause jagged edges if the many nodes are not perfectly smooth.
What it's doing here is that instead of sending a curve command to your CNC machine, it's sending a series of tiny straight lines.
For this review, we want to see if we can generate tool paths from the DXF files download without having to fix anything. So we'll leave the number of nodes alone.
The first step when generating a tool path is to select all of the vectors of the object you're working on designing. In our case, it is the carrot.
There's one more step before creating the tool path: the Vector Validator. Again, we want to ensure that the vectors are clean, meaning there are no zero-length spans, overlaps, or intersections. Any of these can cause unpredictable results on your CNC milling machine.
Our Vector validation passed in all three areas.
It's now time to create the tool path. With all the carrot vectors still selected, we'll use a 60-degree V-bit. Then, with all the settings made, we'll click the Calculate button at the bottom left of the tool path panel.
The result looks good if we run the Vectric tool path simulator.
CNC Router Cutting Engraving Basket With Vegetables On Chopping Board DXF File
The second design I chose to look at is another chopping board with with a basket of vegetables. There are more details on this one.
I imported the DXF files and centered the selected vectors as before.
I again enabled the node editor for one of the vectors in the center of the design. You can see how many node points there are.
I used the Vector Validator tool with all the vectors selected in the Vectric software. Again, I found the vectors were fine.
With all the vectors still selected, I created a V-Carve tool path. We're using the 60-degree V-bit again. Click the calculate button on the bottom left, and we've built our new tool path.
Executing the tool path simulator in Aspire again produces good results.
Both DXF files downloaded have successfully generated V-Carve tool paths, which you can now upload to your CNC machine for milling.
Fit Curves To Vectors
As a point of reference, Vectric software easily cleans up or removes any unnecessary nodes. It's called Fit Curves to Vectors.
In the images below, I did precisely that. I chose to replace the original vectors with Bezier Curves. The result is far fewer node points.
However, I did not replace the original vector with the new Bezier curves vector so that you can compare the two. While they are close to being the same, they are not exact. Depending on your design, it may be "good enough." It's just one of the many design decisions to make when getting your DXF file designs ready for cutting.
If the original vectors with the many nodes were to carve fine, I wouldn't bother cleaning it up.
VCarve Pro Download Files
You must verify all tool path settings, especially the bit settings, to ensure they are compatible with your CNC machine. Every CNC machine operates differently!