Mini-Multitouch Interface

Step 4 Prepare the Lexan touchsurface

This step covers the sanding and polishing of the Lexan touchsurface, for maximum light distribution.

To get the most light into the touch surface, one of the 8-inch edges of the Lexan touchsurface must be made very smooth (this is where the LEDs will make contact with the touchsurface). Ideally, you'll use three materials: 400 grit sandpaper, 800 grit sandpaper, and brass polish. If you don't have brass polish available, you can use just the 400 and 800 grit sandpaper, but the results will be less than spectacular.

Fold a piece of 400 grit sandpaper over a block of wood (or even a small paperback book), and run it back and forth three or four times along one 8-inch edge of the Lexan touchsurface. You should see small white flakes coming off. Repeat this with the 800 grit sandpaper. After each pass with the sandpaper, you should be able to see that the scratches and blemishes on the edge of the Lexan are growing smaller and smaller: this indicates that you're doing a proper job (and isn't that encouraging!). After sanding down the blemishes and bumps, polish the edge of the Lexan (only the edge!) using your brass polish (follow the instructions on the brass polish container).

Admire how smooth and shiny your Lexan edge has become.

Comments

[josheee12]

i personally sanded with 400 grit, 800 grit, and the classic "blowtorch method".

[muthukumaran_m]

Please let me know the size of the sheet, thinkness, length and breath.

[Earl Jr.]

Sheet size is limited only by the brightness of the light source. As for thickness, I've heard 1/4" works the best.