At my university there was a party for all the nerds from computer science and communications engineering yesterday. This was the first opportunity to use the department’s new tables and benches. Although the risk of theft for these things is rather small in our environment we decided to mark the furniture with the logo of our university. The best way to do this is with spray paint and a stencil. Now we just needed a stencil of our university’s logo.
We can get access to a laser cutter but as it is not part of our own lab we are charged 5€ per minute of using it. What we have in our own lab is a 3D printer. So we decided not to cut the stecil, but to print it.
Most things you may want to spray paint have features that do not conect to the rest of the stecil. Therefore you need small bars connecting everthing into one single part. These bars are later visible on your sprayed surface as they also cover the object from the paint.
Here are the problems in our logo marked in red:
Notice all the small features in the signet on the left side.
Now when you use a 3D printer there is no need for your connecting bars to be flat on the surface of your sprayed object. You can build small bridges in the air above the surface that allow the paint cloud to reach the area under the bridge.
So I set out to construct a stecil in my favourite 3D CAD program. The stecil is 2 millimeters thick to be nice and solid. The bridges are 4 millimeters above the painted object while being 1.5 millimeters wide. All bridges are contructed manually.
As our printer’s bed is not big enough I split the stecil in two parts and put them together afterwards with electrical tape.
The rest is shown in the images:
This is my first try to make a 3D printed stecil. There are some things you should watch for when doing this:
- Make features big enough. The main reason why I had to print it this big and in two parts were the very small features in the signet which the printer could not handle in the original size.
- Don’t use too much paint! I used way to much paint while spraying to get everything in solid colors but that results in much excess paint on your stecil that will drop everywhere. Especially if you have to paint many objects with your stecil this is critical. When painting the last few benches the signet was blocked with paint and you can barely read the text there.
- Maybe make the stecil thinner. With a 2 millimeter thick stecil there is plenty of paint sticking to the inside ob the stecil. This paint will run to the back of the stencil and gets squeezed between it and your sprayed object. When the stencil is thinner there is less space for the paint to stick inside the stencil.