Q: What can a CNC machine be used for?
A: For embossing thin metallic foils :)
In continuation to my article about embossing templates printed on a 3D printer I would like to present to you an embossing technique that I have tried and used successfully for some time. It is about making embossing with a CNC machine. In the article mentioned above I presented the generation of some STL files, this files can be imported into your favorite computer aided manufacturing (CAM) program and you can mill the model in wood, plastic or metal, obtaining a template. But no, it's not about making templates on a CNC machine.
You can find CNC embossing machines, machines with considerable strength, which can emboss models in different materials. But it’s not about this, the technique I use does not require machines with great strength. I also found some mini CNC machines that were called embossing CNC machines but in the end it turned out that the term “embossing” was used as a synonym for engraving, which is, of course, wrong.
The technique I propose is simple and fast, it uses a very cheap mini CNC, cheap materials at your fingertips, simple tools and surprisingly good results. In step two I will show you how to create toolpaths for the embossing operation and in step three I will show you the necessary tools, materials and some decorative objects I made with this technique.
I will not insist on how to operate a CNC machine, I especially address those who know the basics of operating a CNC and want to try something new. However, I want to point out that it is never too late to start learning how to work with a CNC even just to use this embossing technique. I also want to say that I searched really hard if anyone else uses this technique and found nothing ... Is it something presented for the first time? :)
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Step 1: Toolpaths
CNC machines use for the milling operation the so-called end mills that have different shapes: square, ball , t-slot, etc. If we take for example the ball (ball nose) mill and the tip of the embossing tool, we can see that the geometry of the two tools is very similar (I mean only at the tip with which the processing is done), as seen from the figure below.
My technique is based on this similarity. In the CAM program I generate a toolpath defining as a machining tool a ball nose (or engraving) mill with the diameter of the ball at the end of the embossing tool. For the first two examples I used the F-engrave program (free, opensource) and for the following two the VCarve Desktop program (commercial).
You can download the program from scorchworks.com, extract the zip file and execute the program.
I imported the template as a bitmap file. Then I generated the toolpath with the values you can see in the images above. Where I intervened:
- Image Height: the desired size of the model;
- Cutter Type: ball nose (or v-bit);
- Cut Depth Limit: depth of embossing;
In the end I saved the generated toolpath.
I could have also generated and saved the toolpaths from Cleanup Operations (V Cleanup and Cleanup), but I wanted to show that the model looks great even without these operations. Take a look at the images above.
The program can be found on the vectric.com page, you can download the trial version to get used to it, I think this version is worth the money even if the price is a little bit high (€330 plus taxes).
VCarve Desktop has the following advantages:
- allows the import of the eps, ai, svg, dxf files ... ;
- allows the import of the STL files;
- you can edit vector files;
- different operations can be selected for different selected vectors;
- editing the geometry of machining tools is very flexible;
- very good toolpath preview
And many other benefits, but it is normal for a software of this caliber.
You can follow the generation of toolpaths in the videos below.
The tips of the embossing tools have diameters of 1mm, 1.5mm, 2mm and 2.5mm so different toolpaths can be generated if desired. Also you can change the values of the depth of the embossing and the stepover value so that a short time processing with maximum quality can be reached. There are so many things to try and it is so interesting to keep trying things to see the results :)
Step 2: Materials, Tools, Process
What do we need?
First of all a CNC machine :)
I recently bought a mini CNC from aliexpress with the intention of using it to make PCB’s. I assembled the kit, tried the machine and it stays unused for several months. But now I thought I'd put it to work, at least to test it so I can see how it works.
So the CNC is available.
I need also:
- a felting block;
- double sided adhesive tape;
- set of embossing tools;
- and many embossing metal sheets of different colors;
- very fine sandpaper or abrasive sponge;
- acrylic modeling paste;
- alcohol-based black permanent marker;
- technical alcohol (I used isopropyl alcohol).
The process I used is as follows:
- I fixed the felting block with the double sided adhesive tape on the CNC table;
- I cut the embossing foil to the right size of the desired model and fixed it so that it could not move horizontally;
- I loaded the toolpath generated, in the CNC control program (in my case Candle);
- I sacrificed an embossing tool, extracted the tip and fixed it in the ER-11 colette (I had a 3mm available, the tip has a diameter of 2mm so I put a piece of paper so that the tip to be well fixed);
- I set the machine to zero and started the embossing;
Step 3: Examples
Below you have two video materials with models made using this technique:
- I The first pattern I finally glued to the lid of a round wooden box
- II A magnet heart with a hidden message (see instructable), antiquated with the method with permanent marker;
- III A small gift with one of my favorite quotes, I wanted to show how easy it can be to make simple models using any type of fonts. I filled with modeling paste the hollows resulted by the embossing so that the model can not be deformed later when the models face is in finishing process
- IV A decorative object made according to the model I used in this instructable, you can see that I also filled the hollows with modeling paste and I antique the foil (I did not succeed as I wanted but I will improve my skills with time:)
This is an entry in the