Sunday, February 3, 2019

Creating masks and text for DSKY substitute display panels



I created the mirror image files for the DSKY display and used the printer at CHM to produce several copies of the dry rub transfer decals which I will use to layer on the acrylic panels. The indicator panel is simply black text which will be backed with some frosted white paint. The EL panel has six white dots, a blue line, and black text to apply, requiring three sets of decals for the various colors. It will then be backed with frosted gray paint.

Three color layers for decals on EL acrylic panel
Multiple copies of text for indicator acrylic panel
The system I use to create the decals has the color layer on the top of the text/image, which means that it is not facing the surface where you adhere the decal. This posed a challenge for my original intent to build the panel by applying decals to the underside of an acrylic panel, since only the underside of the decal will be visible by the user.

I have found that black mylar is good enough even when viewed from the underside of the decal, but I was concerned about how the blue line and white dots would appear. I realized I needed to place these on the top surface of the acrylic, instead of underneath.

The only downsides of placing decals on the top is that they are susceptible to damage and might be visible as raised features. I can spray clear acrylic paint to form a protective barrier over the top. The frosting paint (white or gray) can still be applied to the underside.

I chose to use one sheet for each panel, although I was able to make four copies of the indicator panel on a single sheet so there is redundancy to handle any errors while building decals. The EL panel does not give me the same redundancy, but I printed several copies instead.


Another cosmetic detail to build is the framework around the indicator light sections on the indicator panel. I can laser cut them from thin cardboard stock of the correct color, apply to the top of the panel once I have it constructed, then cover all with clear acrylic spray paint. I did have to check to verify whether I have enough margin around the text to build the framework, but that worked out fine after I shrank the font size slightly.

Framework from a real DSKY indicator panel
After designing the framework, I decided to use the remainder of the 7" x 10" sheet of material, the minimum size from the lasercutting service (Ponoko) to make a mask to fit under the EL panel. My idea here is to narrow the size of the illuminated line coming from the EL wire below, plus to constrain the size of the lighted area behind the PROG, NOUN, VERB and COMP ACTY legends to match a real DSKY panel.

This would sit atop the displays, with cutouts for the lighted legend areas, the three lines, the 21 display digits and the sign area, but block all other light from reaching the panel. I measured the spacing carefully and drew up the cut lines with Inkscape.

The lasercutter requires blue lines that are 0.01mm wide to control the laser for a full cut-through of the cardboard stock. Works fine for the cutter but makes the image impossible to print successfully or view on the screen. I made a copy where I could thicken the lines and make them black, solely for the purposes of printing the design.

I printed the design, cut it out and verified that it exposed and blocked all the portions that I intended of the LEDs, 7-segment displays and EL wires on the PCB. That verified, the order was placed with Ponoko and should be back before the end of the week.


  1. Thanks for the pointer to Ponoko. What system did you use to create the dry transfer decals?

  2. Hi Jack

    I use the DecalPro FX system, works great for me. A bit cumbersome as it involves quite a few steps, but the resulting decals are great.