Laser Cut Plywood Coasters

These were coasters that I made during the course of an internship at a hotel. The bar was using napkins to place drinks on. This seemed very wasteful and didn't really feel up to the standard the hotel was keeping.

Thankfully they had an intern with experience in lasercutting :P who offered to create some samples using the lasercutter at the cities own FABLAB in Aachen, Germany

http://hci.rwth-aachen.de/fablab

The first question is always what material to use. In the past I used acrylic to make some encasement for my arduino and Raspberry Pi. This was very succesful. For the coasters though I needed a cheaper material that could produce good contrasts when engraved. I ended up using 3mm plywood from a softwood tree (poplar or cottonwood).

Plywood comes in different qualities. I chose the highest grade I could find because I wanted the coasters to look like a million bucks.

I find that using different woodwoworking techniques in conjunction with lasercutting will make the result even more amazing.

One of my favourite techniques is staining the plywood. When the laser runs over it for an engrave it will produce an excellent contrast because the stain will be selectively removed in the areas to be engraved.

To successfully stain you need to follow the same procedure as for my Bathymetric Laser Cut map.

First, wipe the panel down with a wet cloth on both sides. The splintered surface will absorb the water more strongly which will allow you to sand it down once it has dried. The splinters will stand upright.

Then Sand with a fine grit like 120 or higher. If you have a larger area to cover then use a machine for more consistent result.

Remove the dust thoroughly from the plywood. Best using an air nozzle hooked up to a compressor.

Now dip your brush in the stain (I used mahogany) and brush it over the panel along the grain and watch it seep into the wood. Apply a lot of stain and keep brushing it forward and backward along the grain and against the grain. The final brush should be along the grain. You can do both sides at once. Depending oon the shade you want you can pat down the stain with a cloth and remove the excess. The longer you wait the darker the stain.

Make sure to provide enough ventilation if you are woking indoors. I had solvent based stain lying around which I used for this.

Give it at least a day to dry and air out all the smell. The final result can only be seen when it has fully dried.

This is by far the easiest part and the fact why I enjoy laser cutting/engraving so much. You have full control via your graphics editor to tell the laser what to do.

Now I dont know about some convention on coaster sizes so this is really up to you. For the sake of simplicity I will say that in diameter a coaster should be 8-9 cm. You can choose different formats and you will also find them in my sample file. Circles are an all time favourite but rounded squares also look pretty neat.

Now, one desing element which I found to be very important is an inner engraved border to give the coaster a better appearance.

In Illustrator or Inkscape, create a shape (circle/square), set the fill to none and make the outer line very thin (0.0001mm) and set its color to blue. It generally helps to work in outline mode.

Now select the outer line of the shape and offset it (I work in Illustrator) so that it creates a new shape within the larger shape. Select this 'clone' and give it a large stroke like 2.00mm.. Then in Object>Path>Outline Stroke.

Now you have your inner border, set its fill to red and its outline to none.

Feel free to add any other graphics to the coasters like a name tag, or a logo or a sentence.

Put your fully dried , sanded stained wood into the lasercutter and open you file which you prepared in your lasercutters required software. At the Fablab in Aachen the progam of choice is the open source Visicut

Visicut links :

https://hci.rwth-aachen.de/visicut

https://github.com/t-oster/VisiCut (By Thomas Ostermann)

Now depending on your laser cutters power you have to choose different settings for engraving and cutting the plywood. Select you red color as the engrave portion and the blue as the cut color. Ignore the rest.

Click Send or Play

Feel free to use these design files and adapt them to your needs.

Unfortunately I dont have access to an airbrushing station because then I would have coated them in a clear satin varnish. I tried this actually with one coaster and it looks pretty cool. A compressor and brush pistol would streamline this whole process compared to a brush only of course. I also attempted to paint some coasters if you like flashy colors. There is also one that I used teak oil on (very smooth)

I tried out a host of different materials before I came to this iteration. Some of which you can see in the sample pictures. I also tried out some three dimensional engraving options.

NOTE ON THE SAMPLE FILES :

I used some alternative colors to denote different engraving styles to the laser cutter like a stronger engrave or weaker engrave or a higher resolution. To use this template more simplifed just change these colors to the normal engrave red.