Use SVG Nest to Minimize Laser Cutting Cost

by | Sep 10, 2016 | Laser Cutting |

The Costs of Laser Cutting

Whether you are fortunate enough to own a laser cutter, or rely on a laser cutting service like Ponoko, when it comes to the cost of laser cutting, you are basically paying for two things:  the material you are cutting, and the time required to cut your design. Obviously, some materials cost more than others, and some materials require more time to cut than others. Regardless of your design or the materials you are using though, if you are interested in saving money on laser cutting, you need to concentrate on reducing, as much as possible, the amount of space occupied by your design.

As far as material cost is concerned, it is obvious how reducing the space occupied by your design would reduce cost. Making your design more compact means you are using less material, which costs less. With services like Ponoko, where you pay for sheets of material of different sizes, managing to squeeze your design into a smaller sheet greatly reduces your cost. Alternatively, you may be able to fit multiple different projects onto a single Ponoko order, which can save you a bunch of money, especially on shipping. If you own a laser cutter and purchase your own material, you are basically trowing away money when you throw away material. Reducing wasted material means you need to buy less.

Reducing the space occupied by your design also reduces the time required to cut your design, which saves money. The speed laser cutters move while cutting is determined by the laser’s power and by the type and thickness of material used. A laser’s cutting speed is, generally speaking, fixed. However, the laser must also move between different cuts. Any time the laser is not cutting material is basically wasted time and wasted money. Clumping your parts closer together reduces the total distance the laser cutter must travel. This reduces electrical consumption, which reduces cost. It also reduces the time required to cut the design, which can save a significant amount of money when using services like Ponoko that charge by the minute for laser cutting services.

Create Compact Laser Cutting Designs with SVG Nest

So we know creating compact designs is critical for saving both time and money on laser cutting projects. But how do you optimize your designs to minimize their size and maximize your laser cutting dollars? It is certainly possible to try arranging your parts by hand; this is what most people using laser cutting in a non-professional setting do. It is a bit of a puzzle, and it takes quite a lot of time, but with some effort you can probably come up with a fairly good arrangement of parts. But the process is tedious and time-consuming.

In this post, I will show you how to use a free, open-source tool called SVG Nest to automate the process of packing your laser cutting files into the smallest possible space. As the creator of SVG Nest points out on the GitHub page for the project, “In the CNC world this is called “nesting”, and software that does this is typically targeted at industrial customers and [is] very expensive.”

1. Create an SVG file the size of your material

SVG Nest, as the name implies, processes SVG vector files.  There are a number of different tools, some free, some paid, for working with SVG files. For this project, I am using Adobe Illustrator. In your vector software of choice, create a new file with the dimensions of your material. If you are using a service like Ponoko, you will have several material sizes from which to choose. If you are using your own laser, simply measure your material.

When using a service like Ponoko, you will choose the size of your material.

Create a new SVG file the size of your material.

2. Create outline around material

This is a simple step. Just draw a rectangle (or whatever other shape you want) that covers the entire work area. This rectangle will serve as a “bin” we will tell SVG Nest to fit all of the parts inside.

3. Add Parts

Next simply add your part outlines into the file. It does not matter where you place the parts, SVG Nest will rearrange all the parts anyway. You just need to make sure none of your parts overlap.

Roughly place your parts into the SVG file. Placement does not matter.

4. Simplify Parts

SVG Nest is not quite as robust as some industrial nesting software so it does not always handle complex shapes well. If your parts feature complex geometry with holes or complicated cutouts, the nesting process will turn out much better if you simplify your parts by removing everything but the part outlines. We will be adding the details back in later on, after SVG Nest has generated an optimal arrangement for parts. For now, just remove any features inside the part outlines.

Simplify your parts by removing any features inside the part outlines.

5. Join Paths

This step, like the previous one, may or may not be necessary depending upon how you created your design. If you created the outlines for your laser cut parts directly in Illustrator, you can skip this step. If you created your designs using some other software, like Autodesk Fusion 360, and imported the part outlines into Illustrator, your part outlines may look like they are a single path, but when you load the parts into SVG Nest, they may read as a series of individual paths. To correct this issue, select each of your part outlines and in the toolbar select Object > Path > Join.

Do Object > Path > Join on each part to ensure they are each a single outline, not several line segments.

6. Upload SVG to SVG Nest

At this point, you should have your SVG file with a rectangle representing the size of your material, and all your parts added into the file. Your parts should have any internal details temporarily removed. With the file preparation complete, we can upload the SVG file to SVG Nest for processing. Go to the SVG Nest website and select Upload SVG. Browse to your SVG File and upload it.

On the SVG Nest website, choose Upload SVG.

7. Choose Nesting Bin

On the next screen, SVG Nest will prompt you to select an area to use as the bin. SVG Nest will attempt to fit all of your parts inside this bin using as little of the area as possible. Simply click on the rectangle that represents the sheet of material you will be cutting.

SVG Nest will prompt you to select the outline to use as the bin for nesting.

Select the rectangle as the bin.

8. Configure SVG Nest Settings

We will need to adjust a few settings to make SVG Nest work the best for a laser cutting project. Click the Configuration button. There are several options in the configuration menu. We will adjust the Curve Tolerance setting to 0.1 or lower. This will help make sure tightly curved areas of parts do not overlap with other parts. Next we will set the Part Rotations setting to 360. This will allow SVG Nest to rotate each of the parts to any angle in the pursuit of the best part arrangement. Last, if your design features many concave areas, you can select the Explore Concave Areas checkbox. This will allow SVG Nest to place parts inside concave areas of other parts. This should result in more efficient nesting, but it also make the nesting process take much, much longer.

Adjust the configuration settings to get better results for laser cutting.

9. Press Start Nest

Next, press the Start Nest button and go get a snack or cup of coffee while SVG Nest crunches the numbers to come up with the best arrangement of parts. The process will take a little while. SVG Nest will continue trying to come up with better and better arrangements until you tell it to stop.

SVG Nest in progress

SVG Nest will continue to try different arragements until you tell it to stop.

10. Download Nested SVG File

Whenever you decide SVG Nest has spent enough time processing your design. Click the Stop Nest button and then the Download SVG button.

Download the nested SVG file.

11. Reinsert Details

If, back in the fourth step, you removed the internal details from your parts, you can add them back in at this point. Just copy and paste your normal designs, matching them up with the outlines in the SVG Nest output file.

If you removed details from your parts earlier, you can copy/paste them back into the finished SVG file.

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