Sunday, November 20, 2011

Let there be light.....and some time to go with it...... The Plexi-glass clock project

  Over the past couple of weeks I have been working on projects such as the Makerbot Semi that I have posted before on my blog and some secret projects that I won't post simple because they are Christmas presents that I want to keep secret.  Along with these projects I have come up with another idea that I hope will interest everyone as it has already for me.  My CNC machine has made it possible for me to make some interesting things like the 40 inch blimp that I just completed so I thought I would figure out the correct way to do engravings with this wonderful tool.  It took me several tries to work out the best CNC machine settings to engrave acrylic plastic and to do so I just took a piece of scrap that I had laying around in my workshop and started experimenting.  With this playing I aquired the know-how to engrave whatever I wanted to make so that it was near perfect and then more ideas started popping up in my head. The photos below will tell the rest of the story.

This is the simple little engraving I did with the piece of acrylic plastic and of course I just had to put my name on it. It is only three inches long and an inch high and a half inch thick.  Nice material that I want to find more of.  After doing the engraving I taped off the back side of the part with painters tape and I cut it to size on my bandsaw and then sanded the cut edges smooth.  The tape on the back of the part keeps it from getting scratched on the table of my bandsaw. The bandsaw by the way cut through this stuff like a hot knife through butter.  The next step was to carefully and slowly heat the sanded edges with a propane torch.  Slowly is the word here as if you go to fast the plastic will simply melt out of shape or worse yet burst into flames. The heating with the torch clears the foggy effect you get when you cut and sand clear plastic and gives you a nice smooth clear finished part. It's nice but not that impressive to look as some people may say and I agree, but that changes once you see the next photo.

Now this looks a whole lot better!  I took a small piece of cardboard and cut a hole in it and then shined a light through the hole.  Then I placed the little name plate engraving into the cut out which in turn lights up the engraving like a neon sign. Again some people will say " what?".  Wait there is more.

Now this is a photo of the famous Pink Panther engraved on acrylic plastic with a red colored light from a lighting base.  Just a bit more impressive than my little name plate engraving. Getting more interesting as I go along don't you think?  Keep reading.

Now comes the idea and another interesting project.  I got to work using Blender 3D graphics on my computer once again and created a 3D model of my idea for you to see.  How about making a plexi-glass lighted clock?  It would be made up of several layers of clear acrylic plastic that would be lit like my little scrap name plate and the Pink Panther. Each column in the clock would have three separate layers of clear engraved plastic.  One number would be engraved on each layer. On the left of the display would be the hours and on the right would be the minutes. This clock would have a black case and background for the display. You could also so the seconds on the clock if you have to be that precise in your time keeping.  Me personally I would be happy that it just displayed the correct time.

This clock is exactly like the previous image only the display would be clear with no black background. The individual numbered layers in any column would be lit by led lights from the base and a small circuit board with an internal clock would keep the time. It could be made to practically any size that you wanted.  My design here would have a display that is three inches tall by ten inches wide.  The overall size of the clock would be a couple of inches more on both dimensions to include the clocks outer case. 
  This would make a nice desk top clock that would not be overly large.  I will have to print out a display on paper to double check that it would not be to big for a desk. If it is I will adjust the display size accordingly. I also plan on making some test clear plastic pieces for lighting each column in the next couple of days.  If this works out as I suspect it will I'll then proceed further and start building parts for the Plexi-glass clock project.
  Follow along with me and we can both keep our fingers crossed that it will all come together as I have planned.


  1. I've been wanting to try this for ages! Any tips on the milling? What depth did you mill to?

    As for the seconds display, wouldn't it be interesting to use the minute display but a different colour light? So the minutes show up in red and the seconds are overlaid in green?

  2. Depth for the simple engraving with my name on it was only .02 of an inch. I ran it at 10 inches per minute and slowed the speed down to around 8-10 thousand rpm.