Thursday, March 7, 2019

cut cable entries in DSKY enclosure and started on the text/graphics installation on acrylic panels


Cable entry and orientation

I chose to route the cables in and out of the DSKY from the bottom face. A few holes and slots were drilled and I test fit the cables. I have to epoxy some rubber feet to the bottom to provide clearance for the wires.


It was finally time to create all the decals and transfer them onto the two acrylic panels. This is a process I have accomplished successfully many times before, but does demand care and attention to get it right.

I have printed the text, dots and lines that will become the details, using a special printer paper. The toner is baked onto the surface by the printer itself. The actual process will consist of four separate decals. One for the indicator panel, then three for the EL panel since it has white dots, a blue line and black text.

I cut up the special paper with the printed text, applied a mylar sheet with the desired color on top, covered it all in clear plastic and pass it through a hot laminator. The lamination causes the toner to absorb the heat, melting the colored mylar atop every printed feature. The mylar is fused to the paper, but only where toner existed.

I peeled off the rest of the colored mylar, which left just the printed area with mylar adhered to each letter/graphic. Some cleaning prepared this master for the next step where I removd the backing paper to leave the mylar and decal..

I covered the master with another, clear mylar sheet that has been rubbed to create a static electric charge. Running this through the laminator a second time makes a sandwich of mylar film, the mylar fused letters and the paper,  which is then slid into cold water. The special paper dissolved in water, leaving the clear mylar to float off with the colored text/graphics stuck to the bottom.

This is the decal - all the graphics and text are clinging to the mylar because of the static charge. Since it is simply a static charge, however, they will separate relatively easily and without any ripping. The colored part of the text is up against the mylar, with the underside available to take a quick spray of adhesive.

The decal is placed atop the desired surface, in this case an acrylic panel, and rubbed to cause the letters to glue down to the panel. Peeling away the clear mylar sheet leaves just the text and graphics stuck in place as intended. This is the DecalPROfx system.

The first decal I applied was the blue line, since I could apply a narrowly focused adhesive spray to just the area under the line. The image below has reflections and doesn't show off the transferred mylar but it looks good in person.

Blue line applied to smoked gray acrylic panel
Second up would have been the decal that puts down the white dots. With those in place, I would make the decal with the text (e.g. PROG, VERB, etc) and rub it onto the panel.

Unfortunately, I miss-cut my printed paper and ruined the white dot and black text sections. I will need to print this on somebody else's laser printer since the Brother brand which I have does not produce good toner for this system. I will get back to this perhaps tomorrow when I drive over to use another printer.

Having been stymied by my own error, I turned to the indicator panel. That had a single decal with the black text for the fourteen different conditions that are lit up (e.g. GIMBAL LOCK,  RESTART).
A lasercut cardboard mask is then glued over this panel, providing visual separation of the fourteen indicator lamp areas. A matching light dam below keeps any LED illumination contained to the intended cell, thus lighting only that one of the fourteen areas.

Image printed and black mylar bonded to it
One peculiarity of this system for producing decals is that you have to ascertain the axis of bending when the paper hits the water. If it goes in the wrong way, it is very hard to get the mylar to release from the paper without destroying the printed image.

The directions tell you to observe the paper as you remove moisture from it - a hot air gun is applied to the paper to drive out moisture. Sometimes, the way it bends when first heated is NOT the way it will bend in the water. I got it right for the blue line decal, but my indicator panel text decal rolled up like a cigar, the wrong way.

Amazingly, it wasn't too bad. I lost a bit of the border band but the text was good. I sprayed it with adhesive and moved on to install it on the acrylic panel. Alas, I got the alignment wrong. Once the text touches down even for an instant, you can't move it. I have a panel which has great text but misaligned so it isn't useful.
Mylar with text clinging to it by static electricity
Sadly, I let it touch down off center, ruining this try
Text offset because of flaw but shows how it will look in operation

And in face frame

No comments:

Post a Comment