In this instructable I am going to describe how you can make an led edge lit glass mirror with a Snowman design, perfect for Christmas!
The sign is engraved on a glass mirror tile from Ikea. These come in packs of four and are quite cost effective.
I have used a Dremel 290 tool for the engraving but there are lots of other methods that can be used, e.g. cnc router, chemical etching or sandblasting. Another option is to use a Dremel drill or other rotary tool and an engraving bit. The main advantage of a Dremel engraver over a rotary tool is that it has a reciprocating action, in other words it vibrates rather than rotates, which makes engraving easier.
The sign is lit by a WS2812B programmable rgb led light strip. These can be purchased in various lengths with wires attached or in whole reels, which can then be cut to length at the marked positions.
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Step 1: Video
Step 2: Parts & Tools
Power supply - 5 Volts 1 Amp
Regularised framing wood - each side:
16-1/2" x 2-1/2" x 3/8"
422 x 68 x 32 mm
Pallet wood - each side:
16-5/8" x 2-3/4" x 1-1/4"
418 x 62 x 11 mm
1/4" or 6mm wooden dowels
1/4" or 6mm straight router bit
1/8" or 3mm straight router bit
1/2" or 12mm straight router bit
Step 3: How an Edge Light Works
Reflection in glass or acrylic
An edge light is made from a transparent sheet of material,with a light source located on one or more edges.
Light travels through the sheet, without escaping the surface, because of refraction.
Refraction is the way light bends when it passes from one medium to another.
If the light is travelling towards the junction at greater than the critical angle, then the light will be reflected and this results in total internal reflection, where the light bounces between the flat surfaces of the glass.
When the light reaches an edge or an engraved area of the sheet, then the angle is less than the critical angle and the light escapes.
The critical angle depends on the refractive index of the two materials and for glass and air it is about 42 degrees (from the perpendicular).
Reflection in a mirror
With a mirror one of the surfaces is coated with a thin metallic layer of silver or aluminium.
Instead of the light photons being reflected due to refraction, the atoms in the metal layer absorb them. This makes them excited and unstable. They can’t hold onto this energy and release it back as photons, reflecting the light.
The opposite side of the mirror continues to reflect the light by refraction.
Engraving removes part of the metal and glass layers, which disrupts the reflection and allows light to escape.
Step 4: Engrave the Mirror Tile
I created the 3d snowman image with the help of a graphics tablet.
Remove the protective backing from the mirror tile.
Centre the image on the tile.
Tape one edge of the paper image to the back of the mirror tile.
Glue the rest of the paper to the mirror tile with water soluble glue.
Engrave the image with an engraver or a rotary tool with an engraver bit.
I used a Dremel 290 engraver which has a reciprocating action (it vibrates rather than rotates) which makes it quite easy to use and allows the use of a ruler for straight lines.
Once the mirror has been engraved then the remaining paper can be washed off.
Step 5: Frame Design
The frame for the mirror is made in two sections that are glued together.
The front section is made from recycled regularised framing timber, with a rabbet or rebate cut along one edge in which to locate the mirror tile.
Then a second section is made out of pallet wood to increase the depth of the frame.
The size of the wood is not particularly critical, use what you have got.
Step 6: Front Frame - Route Profile
Cut wood to length
Cut the framing wood into four lengths.
Route profile on all four pieces
Set the fence on the router table to cut a width of 6.5mm or 1/4".
Route rabbets in all four pieces to a depth of 9.5mm or 3/8".
Route led strip profile on only one piece
To allow the mirror edge to sit directly on top of the leds in the strip, an additional groove or slot is routed in one piece of wood.
Using a 3mm or 1/8” straight router bit, cut a groove at the end of the existing rabbet, giving a total width of 9.5mm or 3/8”.
The depth of this groove should be 13mm or ½”.
Step 7: Front Frame - Cut Mitres
Cut 45 degree mitres on one end of each piece of wood.
Use the mirror tile to mark the inside width on one piece of wood. In the video I cut a 45 degree mitre on this piece to identify it easily.
Add 3mm or 1/8” to this mark (for clearance).
Then using the 45 degree angle on a speed square (roofing square in the UK) extend the line to the outside edge.
Using one of the 45 degree off cuts as a stop block, position the piece of wood on the mitre saw and lock the stop block in place with a clamp.
Make sure that the mitre is angled in the correct direction, as it is very easy to get this wrong. If you get the first piece right then the 45 degree stop block will ensure that all the other pieces are correctly orientated.
Cut the second set of mitres on all four pieces of wood.
Assemble the four pieces of wood and check that the mirror
is a good fit with the led strip.
If there is too much free space then you can adjust the stop block and recut the mitres on all four pieces until the mirror fits.
Step 8: Front Frame - Strengthen the Mitres With Loose Tenons
To add strength to the frame I used loose tenons on the mitred edges of the four pieces.
The loose tenons were strips cut from 6mm or ¼” plywood.
To cut the mortices I used a router table with a 6mm or ¼” straight bit.
45 degree stop blocks made from offcuts were used to prevent the mortices extending to the edges.
Once the tenons on one side of each piece of wood has been routed, then the stop blocks are swapped over and the opposite sides can be routed.
Step 9: Front Frame - Cut Notch for the Led Cable
To allow clearance for the led strip power cable a notch is chiselled out of piece of wood.
Step 10: Front Frame - Glue Up
Apply glue to the mitres, mortices and loose tenons.
Assemble the front frame.
Clamp the frame with a band clamp.
Wipe away any excess glue.
Check that the frame is square and that the two corner dimensions are the same.
You can also check that the mirror tile fits correctly.
Leave to dry.
Step 11: Rear Frame - Cut Pallet Wood to the Same Width
Select four pieces of pallet wood with the same depth and roughly the same width.
I ran each piece through the table saw, cutting off a small amount to create one flat edge (flat enough anyway).
I then cut the opposite side of each piece to the same width.
Step 12: Rear Frame - Cut Mitres
Cut 45 degree mitres on one end of each piece.
Mark the length on the piece. I made it slightly smaller than the width of the front frame.
Using a clamp to hold it in position, cut a 45 degree mitre on the opposite end of the piece.
Then position the 45 degree offcut as a stop block and clamp it in position.
The three remaining pieces can then be cut to length.
Using this method means that all four pieces are exactly the same length and as long as the mitres are cut at 45 degrees, then the frame fits together neatly.
Step 13: Rear Frame - Route Rabbet for the Back
To allow a back to be fitted, a rabbet or rebate is routed along one edge of all four pieces.
Step 14: Rear Frame - Glue Up
Glue the mitres.
Clamp with a band clamp.
Wipe away any excess glue.
Check that all four corners are square and that the corner dimensions are equal.
Step 15: Rear Frame - Reinforce the Mitres With Dowels
Drill holes at 45 degrees through the corners using a mitred piece of wood as a drilling guide.
If you don’t drill all the way through, then you don’t have to worry about the holes exactly lining up on the opposite side.
Using a brad point drill bit carefully drill until the point of the drill just starts to break the surface on the opposite side. This leaves a tiny hole that allows the glue to escape when the dowels are inserted.
Glue and carefully hammer the dowels into the corners.
Wipe away any excess glue, the tiny holes should be invisible.
Cut off the excess dowel with a Japanese type pull saw.
Leave to dry.
Step 16: Assemble the Front and Rear Frames
The front and rear frames are glued together.
Clamp, using as many clamps as you can muster.
Leave to dry.
Step 17: Fit the Led Tape to the Frame
The lighting used for this project is a WS2812B programmable colour RGB led tape.
The tape can only be cut at the marked positions.
The ends of the tape are usually fitted with connectors; this is so that the tapes can be connected in a chain.
One of the connectors will mate with the connector on the led controller. The other won’t, so make sure to select the correct end of the led tape when cutting it to length.
At this point it is a good idea to check that the led tape works with the controller and also to set the number of leds operated by the controller. On the controller that I used this was set from the remote control.
Using the groove in the frame as a guide find the correct length for the led tape.
Cut the led tape to size (only at the marked positions).
Once again check the led strip works correctly.
Remove the adhesive backing from the led strip and stick it in place. In the event that the adhesive is not strong enough then I have found that Super glue gel or cyanoacrylate works well.
Step 18: Fit the Mirror to the Frame
Fit the mirror – the edge of the mirror should sit directly on top of the leds. If they don’t then the edge lighting will not work!
Cut a square of plywood to cover the back of the mirror.
I used glazier points to hold the plywood in position. These are tapped into position with a screwdriver.
Step 19: Fit the Led Controller
The remote control for the led controller operates by infrared.
Note that some remote controls operate by RF, which makes this step unnecessary.
To ensure that it can be seen by the controller:
Drill a small hole through the front frame.
Enlarge the hole at the back.
Fit the receiver from the led controller into the hole.
Connect the led strip to the controller.
Plug the power supply into the controller and check that everything works okay.
Step 20: Fit the Back
The back of the mirror is covered by another square of plywood that sits in the rabbet routed into the rear frame.
To hang the mirror on the wall I have used a French cleat. A French cleat simply consists of two lengths of wood cut at an angle, one is attached to the mirror and the other to the wall. They then lock together for a very secure attachment.
Cut a length of wood to the width of the inner frame.
Using a table saw set to 45 degrees, cut the wood down the middle. This then forms each half of the French cleat.
I added an extra length of wood to the top of the frame to give the French cleat something to attach to.
Cut a length of wood to fit the inside of the frame.
Glue and screw in position.
Install the plywood square.
Glue and temporarily attach one half of the French cleat in position with short screws.
Then remove the plywood back complete with the French cleat and screw it together from the back.
One corner of the plywood square was then cut away so that the power supply cable could be routed through the bottom corner.
Reposition the plywood square and replace the temporary short screws with longer screws to attach it firmly to the frame.
The rest of the plywood back was attached to the frame with self-tapping screws.
Step 21: Wall Mounting and Testing
The second half of the French cleat is screwed to the wall and the mirror hung from it.
The remote control has several options for changing the light colours, pattern and speed to your taste.
In the second part of this instructables project I will add battery power, replace the controller with an Arduino and add some other interesting electronic modules, so please look out for that.
The instructable is entered in a competition, so please vote!