onsdag 24. februar 2016

Laser cutting worbla

I very recently learned how to operate the laser cutter over at Bitraf, motivated purely by my desire to make a Transistor sword. After that I have gotten a couple of questions on how to use this technology, especially after my demo of cutting worbla. Here are a few thought from my side. 

You need to know what to cut, and for me I often need made to measure components :) Bearing in mind that the cutting surface of the machine I have access to is 500x700 mm then those are my limits. Also it cannot cut anything thicker than 6 mm (at least in one go). And not to mention only use materials that are safe to cut (PVC will produce chlorine gas, so that's a no)

But worbla, acrylic, mdf, plywood, paper etc are safe to use. These all require different settings though, more on that later.

I like to draw my own schematics, for this I use vector graphics (the pen tool) in InDesign or Illustrator. Your file need to ultimately be saved as a .dxf file to be uploaded to the laser cutter. If your program doesn't convert to this file you can download for free inkskape. Upload your design, eg in pdf format and then export to .dxf from there. 
Settings in Autolaser
The machine at Bitraf is connected to a computer via Autolaser. From this program I can see and in some degree alter my design after it is uploaded as a .dxf file. This is also where I set the settings for the power and speed of the laser. You need to keep in mind what material and the thickness of said material when adjusting the setting. 

Screendump from Autolaser. For worbla settings, see section below. 

Worbla as example
As I got a specific question for settings for cutting worbla I will use that as an example. Settings will be different from machine to machine, so you might have to fine tune it if you are going to try out this. And not to mention that the humidity in the room and other factors again change the game and can fuck up your cutting job. 

After several tries I concluded that 40% power and 30 m/s speed did a great job. Higher intensity just melted the edges slightly more, but no burned edges even at 100%! 

Prepping the material
Worbla can easily warp and warped material can get hooked in the laser head then either destroying the machine or move your material out of place. Or your worbla can melt down into the honey comb, thereby making a mess to clean up and destroying the piece you were cutting. 

You need to make sure your worbla stays flat. I heated up my piece of worbla and taped it to a piece of mdf. This way I can also cut the worbla in thin pieces that would other wise deform while warm, they will stay in place and will be easy to remove from the machine since it is already laying on a board.

I prefer to wait until the worbla had cooled completely before detaching the parts I want.

Now you can transfer your worbla your prop :)

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