Introduction: Bar's Open Acrylic Glass Engraving

About: I'm a DIY and photography enthusiast who loves to make stuff in his spare time. My DIY interests are pretty diverse, mostly I see something I want to make or a technique I want to learn, then start doing it un…

This was my very first real DIY project which I made all the way back in 2009.
As back in the day I never even considered making a how-to, there are no progress pictures and any pictures taken were taken with the means I had - a very humble N97 cellphone camera. I apologize both for lack of progress pictures as well as for the image quality and will try to make up for that with extensive descriptions of what I did and what my thoughts were.

Anyway, in those days a friend of mine got his own flat and in my friend circle this was a huge deal as we'd all have a place to crash and party at.
For his moving-in-party I wanted to make him something that he could hang on the wall and which would be something party-related. I came to the conclusion that it'd be awesome to have a light-up wall display which we could light up everytime we'd come by to party.
Sadly, he never had a moving-in party. Less sad, I could thus keep this display (he got a different gift instead).

Make a party-ish, battery-powered acrylic glass engraving which is edge-lit by 8 groups of 2 LEDs each with a total of 4 different colors (1 per side), effectively resulting in 2^8=256 lighting combinations.
Make a wooden frame for it so it can be hung on a wall.
Construct the whole thing that it can be easily and completely disassembled for repairs.

Safety Advice:
This instructable makes use of (power) tools, knives and soldering irons.
These tools can burn, cut or otherwise hurt you and potentially seriously hurt you.
Always wear eye protection (a molten piece of acrylic being flung at your face is not fun, trust me on this one) and be extra careful where your fingers/hands are at any given moment.
In general, before doing each step, think about what you're doing, which tools you're using and what potential dangers are involved.
If you are not experienced with the use of the tools, get help from someone who is.

- Router
- Drill
- Chop saw
- Dremel (router attachment is useful)
- Soldering iron
- Pliers (especially for wire cutting and stripping)
- Cutter knife
- Sandpaper
- Pencil / (permanent) marker
- (Folding) Ruler
- Clear varnish
- Screw clamps (optional)

- 2x5cm wood piece for the frame (long enough for all frame sides together)
- 1x5cm wood piece for the battery holder
- 8mm thick GS acrylic glass (big enough for your motif, plus about 2cm width + height extra)
- Black paperboard/cardboard, as large as the acrylic glass you're going to use
- 4x 5mm LEDs each of white, blue, green and red color (16 LEDs in total)
- Resistors (resistance depends on LEDs used and how they're connected)
- Luster terminal (for 10 connections)
- 8x On/Off Micro-switches (I used 4 double ones)
- Bunch of cables, preferably of different colors
- AA battery holder for 4 batteries
- Heat shrinking tube
- Soldering tin
- Paintbrush
- 2x 10x5mm Metal pins (e.g. a thick nail cut into pieces)
- Small nails
- Screws
- 4x Metal angle
- 2x Image frame hook

The Build:
1. Decide on and prepare the image
Using the free image editor GIMP I cobbled together an image to my liking which would fit the spirit I had set as my goal.
The image was converted to black-and-white, scaled to the correct size, then as you can see with images 2 and 3, flipped horizontally (left became right and vice-versa). The reason for this is that I was going to engrave the back side of the acrylic glass, so the image and especially text had to be mirrored.
The image was then printed in black and white.

2. Get the right acrylic glass and cut it to size
This is an important, possibly the most important step.
There are generally two kinds of acrylic glass you can get: GS (cast/poured) and XT (extruded). What you want is GS glass. Why do you want GS glass? Because of two reasons. One is that GS glass does not fracture as easily as XT glass, but more importantly, GS glass has a higher melting temperature which means unlike XT glass, it will not melt and wrap around your sawblade or router when cutting/carving, thus ruining the glass and possibly your tools. Inexperienced as I was, I used the cheaer XT glass first, promptly ruined it and had to spend half an hour cleaning my tools. Learn from my mistakes!
The next piece of glass (GS this time) I had cut into the right size at the shop where I bought it as I did not have any tools to do so myself properly at the time. If you have a table saw, skill saw or a jig saw you can use blade either for plastic or metal to cut acrylic glass, they both work just fine.
Mind to add about 2cm extra in width and height to the size of the glass as part of it is going to be hidden inside the frame.

3. Engrave the image
The better method is the following:
Leave the protective foil on the glass, transfer your image onto the protective foil and engrave through it to avoid scratches on the glass.
The method I used was the following:
I removed the protective foil, used scotch tape to tape my printed image to the glass, flipped it around and started engraving.
The problem here was that I caused scratches. Luckily there's some awesome stuff generally called "Acrylic glass scratch remover" which you should be able to find at the boating department of your local hardware store. Follow instructions on the front/back and get rid of any scratches; that stuff is amazing!
Now for the engraving itself.
I used a dremel with a miniature router attachment so that I could control it quite well with both of my hands. The dremel was going at about 15.000-20.000RPM, so rather high speeds. I set the proper height on my router attachment, then just carefully 'stabbed' into the glass and used both hands to control the movement, moving it ever so slightly and carefully, stopping in between to remove excess acrylic glass 'shavings'. Oh, did I mention to wear protective goggles? The acrylic glass pieces tend to get slingshot into your face, so it's highly recommended to wear eye protection. And keep your mouth clothed, that stuff doesn't taste too well either. Clean the engraving and carefully remove all excess acrylic glass with a cutter knife.
Now for another important part of the engraving, the dremel router bits I used:
For this engraving I used a bit that looked something like a miniature round rasp, it worked really well. In later projects/experiments I learned that especially for finer lines bits that look like they consist of lots of tiny, sometimes serrated blades forming a shape (e.g. a cylinder or cone) work really well for this application as well.

4. Drilling holes for the LEDs
I wanted the LED's to be equidistant and with four LEDs per side, I took the length of the given side and divided it by 5, then marked those positions on the edge of the glass using a permanent marker.
Now, I wanted to sink the LED's into the glass to save space, which meant I needed glass slightly thicker than my 5mm LEDs, which is why I went with 8mm acrylic. I used a cutter knife to carefully score the middle (4mm) of the glass at the previously marked points to prevent my drill from sliding away as I only had a tolerance of 1.5mm to each side.
To prevent cracking of the glass, I started with the thinnest metal drill I had at my disposal, then used small increments up to the needed 5mm diameter which made a hole where my LEDs fit in perfectly.
I drilled just deep enough for the LEDs to sit flush.
Again, I used metal drills for this. If the drill gets stuck, stop immediately and carefully try to remove it per hand. I also experienced that drilling with higher speeds worked better, though I was more likely to crack the glass when I slipped.

5. Preparing the frame
I took a piece of 2x5cm wood a bit longer than all of the combined sides of the acrylic glass (accounting for mistakes) and positioned it upright, lying on the long 2cm side. I used a router and two different bits to bevel the edges of the side facing up as those would be the side of the frame facing the viewer.
Then I laid the wood on its flat side and used the router to make a ~1cm deep notch wide enough for the acrylic glass to fit in easily about 1cm away from the beveled edge. Note that the beveled edge on which side you're making the notch will become the inner side of the frame.
Laying the wood upright again I used a chop saw to cut two long and two short pieces to fit the acrylic glass, each piece with 45° angles pointing insde (so the side of the wood with the notch would be shorter than the outside).
Note that the long and short pieces respectively need to be exactly the same length for the frame to fit properly. I wasted quite a bit of wood on this before I got it acceptably right.
Test-fit the frame and check if the acrylic sits well inside, accounting for about 1cm of the acrylic to be inside of the wood using the notch just made.
Now mark the positions on the inside of the frame where the LEDs will be, meaning just use a pencil to mark the middle of the holes drilled in the acrylic glass.
Use a router to make a short cable canal orthogonal to the notch, away from the beveled edge. If you do not know what I mean, look at picture 6 (the back side with all the cables) and check where cables appear to be coming out of the frame. This little recess is what you want to make.
To check if it works, put in an LED in the drilled slot in the glass, then bend its legs over twice to that they're laying flat on the engraved side, then asseble the frame. The legs should be clearly visible thanks to those new notches.

6. Make the battery and luster terminal holder
Leaving the frame and glass dry-assembled, take a piece of 1x5cm wood and cut it so it fits vertically in the middle, just like in picture 6.
Put it in and mark its middle as well as this position on the frame pieces it touches.
Drill a hole in those ends of the battery holder piece big enough for a metal pin (for instance, a thick nail cut into ~1cm long pieces) to fit and drill according holes into the frame. The metal pins do not need to fit snug, a little wiggle room is alright.
You can now use small nails or similar to attach the battery holder and luster terminal to that piece of wood.

7. Make a recess for the switches
I decided my switches would be accessible from the outside, on the right side, sitting flush with the wood.
If you want to save yourself the trouble, just attach them to the battery holder piece of wood.
I marked the position where the switches would be positioned with a pencil, then used a router to make a recess just deep enough for them to fit snug with a couple milimeters depth extra for the cabling that will follow. I used a cutter knife and sandpaper to correct the edges of that recess. Once that was done, I used the router to deepen about half the width of the recess so it went all the way through the frame. In essence, a crossection of that part would now look like stairs, with the switches sidding on the middle step and half their pins dangling down the newly-made hole.
The reason I cut the recess like this was so that the micro switches would sit flush and couldn't be pushed in deeper while allowing for half the pins to get access to individual cables.

8. Soldering / cabling
Now this is probably the step where I messed up most due to my inexperience, so here's how it should be done in a better way instead:
- Connect the positive pole of the battery holder to the lustre terminal
- Use a cable from there to connect one side of all the switches. Just put the switches next to each other, strip the cable long enough, then put it under one half of the pins and bend them over to secure the cable, finally soldering it in place.
- Next, take two LEDs of your liking per side and with a correct resistor (google "LED resistor calculator" or similar to find out which) connect them in serial by soldering (remember to insulate solder joints with heat shrink tube), then connect the positive cable of this chain to the luster terminal. Rpeat this for the remaining LEDs.
- Connect that slot of the luster terminal to a free switch pin with another piece of cable. Repeat this process with the other 7 LED chains.
- Connect all negative ends of the LED chains together in the lustre terminal and connect the negative pole of the battery holder to that.
- Put in batteries and test if all works properly.
I know this is a really confusing part, just think a bit about it and you'll find a configuration that'll fit you.
If you just can't seem to understand it, ask me about it and I'll draw up a basic schematic for clarification.

9. Finishing the wood
Use sandpaper with 120 grit (or finer) to smooth all pieces of wood.
Then use clear varnish to finish/protect it. I put on three or four layers of varnish.

10. Assembly time!
First take the acrylic glass (if you didn't get rid of the protective foil on the glass yet, now's the time), then cover the engraved side with a piece of black cardboard the same size.
Next, insert the switches into their recess, then the LED's and put the frame together (remeber to use the metal pins to secure the battery holder piece of wood). If the glass has too much room, use tiny bits of wood or foam or something similar to secure it in place. You can now connect all the wiring using the luster terminal and check once more if everything works.
If it does, insert the metal angles into the corners of the inside of the frame and use short screws to secure all pieces together.
Screw clamps are useful to keep the frame pieces in place while doing so.
Use nails to attach image frame holders to the upper back of the frame at positions you find convenient. I put them at about 5cm distance from each side.

Conclusion / Thoughts / Improvements:
- Total project cost ~40-50€
- Cabling should've been done in a smarter way
- To save money, SMD LEDs and thinner acrylic glass could've been used. This would also prevent the need of drilling into the sides of the glass.
- Engraving, as described above, should've been done with the protective foil on. This would have saved having to polish the glass with acrylic glass scratch remover.

Any questions?
Ask away!
I'll try to answer anything to the best of my ability.

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