I begun experimenting with a special rubber which can be engraved by laser to make personalized stamps.
Step 1: Material and Tools
The laser machine you see in the picture is the bigger one of the WeMake fab-lab here in Milan, and I used it to cut the wood support for the stamp. I used the smaller laser cutter to engrave the rubber, you don't need much power, although with a more powerful machine you will take probably less time.
Step 2: Choose the Graphic
Then enlarge or reduce your image to about 1200 pixel. This will let you apply effects with a certain standard.
Also remember to flip the image around the vertical axes, since the stamp will be mirrored. I forgot to do that with my Supermario.
Step 3: Extract Outlines
Duplicate the layer, take the top one, apply the "stamp" effect, play with settings to obtain the better b&w outlines image, then refine it with the pencil tool.
Step 4: Apply Pixelate Effect
You have to decide now how much detailed will be the shades of gray, the smaller the dots are, the more precise tints will be, but thin rubber spikes will be hard to maintain.
Use a value from 12 to 18 as max radius and 45° for other settings. Apply the effect to the background layer.
Step 5: Remove Outside Dots and Refine White Areas
Now you can choose which details of your image shall be totally white, like eyes and teeth. Go on the background layer and paint them with white.
Step 6: Optional: Add a Thin White Space Between Outlines and Filling
To do that you have to select the empty areas and reduce the selection of about 4-5 pixels. Then invert the selection, make a new layer, fill it with white and place it between outlines layer and background layer.
Step 7: Save the B&w Image
Step 8: Convert Raster to Vector Image
Illustrator has also the same Pixelated effect, and so you can do everything with this software.
Open a new document and drag your raster image on it, then go on window -> image trace and open image trace settings window. Choose b&w, open advanced settings, and play with them until you're satisfied. I only changed noise to about 20. Try also "ignore white" setting.
Then click on "expand" button, which will explode all into shapes. Select all and ungroup everything.
Step 9: Remove Hidden Duplicates
Click on a black area, then select -> same -> fill color, and object -> hide -> selection. This will apparently hide everything, but select -> all and you will see there are white areas which you wont need. So cancel them, and object -> show all.
Step 10: Outlines for Engraving and Cut
Step 11: Save the Vector File
Then save the file as .dxf with R14/LT98 version, 1mm scale, and "maximum editability" checked.
Step 12: Import the Vector File
There could be some self-intersect lines, just ignore them if you don't have patience to fix the dxf.
Step 13: Choose Right Settings
Choosing right values for laser speed and gap is the difficult part. Power is usually at 100% to optimize the job.
I made some tests with the 60 watt laser. To engrave that rubber foil you need a quite slow speed, and a very low gap. But if you exceed lowering these parameters you will lose details. I decided that a value of 100 speed and 0.06 gap is quite right, deep engrave and good detail although slow process.
You can also try to use gap 0.10, to be faster. Look at the pictures to see the different appearance of slopes on types borders for different values of grade width. First line of bigger test rectangle is made with simple engrave (no grade).
Step 14: Upload File to Laser Machine
Choose in the software menu as starting point the left-down point (or another one as you wish) and place your rubber sheet on the machine plane.
Step 15: Start the Engraving Process
Then click "esc" a few times to go back to home menu, and move the laser so that it's on the starting point you chose before. With "test" button you can see the perimeter of the job and check that you have placed rubber right.
When you are ready close the cover, start chiller and air compressor, and click "start".
At the end of the process you can click "datum" to send the laser to home, and take out your stamp.
Step 16: Laser Cut the Stamp Support
I used the bigger laser machine of WeMake workshop, more powerful than the other one.
In software change colour of the external line, assign to that colour "cut" parameters as in the picture (100 power, 25 speed) and check output only for that layer. Place board, upload (or "download" if you follow software label) the file to the machine, and start the cutting. That is really fast compared to the engrave process.