Glues:

Solvent Cement: As I have used in the past I could use a solvent cement to join the acrylic components. This glue works via capillary action so the edges to be joined must fit together perfectly, it shouldn’t be difficult to get perfect edges using the laser cutter but I don’t think this join will be strong enough for the safe.

Araldite: This would give a strong joint with edges that may not fit together exactly, it can fill small gaps. Hmmm on testing it’s quite messy and does not look very good on clear acrylic.

Joins:

A mechanical join combined with the solvent cement could give the strength needed:

This edge would require a channel to be ground in the top and bottom edges to fit the side panels, I could achieve this using the CNC miller.

For this one I would cut tabs and holes for the pieces to fit together, this is the most promising method as it gives strength, makes it easy to fit accuratly without glueing and also adds to the asthetics. I wouls also make the manufacture simpler as all the pieces could be drawn in 2D design and cut using the laser cutter.

Hinges:

I need to get the door to open (otherwise the safe will be a little too safe…) so hinges will be needed. As the case is to be made from clear acrylic it would be nice if the hings matched.

It would be quite elegant if the hinge could be part of the door itself though. After a discussion with Dean I have decided to use a tab on the top left hand and bottom left hand corners of the door, corresponding to two holes in the case to act a pivots, testing to come in my next post.

Components:

After putting the circuit together I can see that there are no spare pins to add in new sounders or lights (humph) I can exchange the bi-colour LED for one green and one red by wiring both to the same point in the PCB. The Bi colour LED works by lighting up red when the current runs through it in one direction and green when it reverses. With the red wired anode to anode and cathode to cathode and with the green wired the opposite way round it should work in the same way.

I did find a really cool component that I would have loved to use (and still might in another project) called EL wire (electroluminesent wire). It’s a thin copper wire coated in a phospher that glows when alternating current is passed through it. it’s flexible and can be run off battery or mains power.

All the pieces slot together so I can construct the box and check any fit issues without needing to glue anything.

After extending the battery cable I realised that I have not allowed space for the on/off switch, a bit of a silly oversight but one easily fixed. I produced a simple drawing in 2D design using the layout of the piece the switch is to fit to, by making the paper setup the same dimensions as that of the piece to be cut it was a simple matter of placing the acrylic back into the laser cutter and setting it off, hey presto…

The next step was to test the door in it’s final position. A couple of changes need here as well, as you can see from the first picture below the door would not shut with the battery cable leading down to the pack, the inner case needed a recess for the cable to sit into to allow the door to lie flush to the face of the box. A better solution however was to cut a hole to pass the cable through as this would prevent the cable from slipping out of place as in the second image.

Another problem was that the door was catching on the metal supports on the inside of the green box (see top image). I had already faced them off on the manual lathe to get rid of the bump from the CNC lathe (see below) to fix this I decided to drop the box by 2mm by taking the inner supports down on the manual lathe. This fixed the clearance problem and allowed the door to swing clearly.

All that is left to do now is to finally fix everything together permanently, starting with fixing the inner supports to the bottom of the blue box and the bottom of the green box. I decided to use Araldite liquid steel as I had gotten good results when using it in my other project. Each support was pushed through it’s opening and coated with adhesive, the connecting piece was then pushed down and held in place with masking tape till dry. I also glued a piece of black acrylic to the underside of the inner box to attach the battery pack to, this looked far neater than seeing the glue through the bottom of the inner box.

Once the inner supports were dry I could use the capillary glue to run along the edges of each tab, tape it securely and wait for it to dry. The outer box was a little more complex as the door needed to be in place before it could be completed.  I started by gluing the outer supports to the base, fitting the door, placing the top of the outer box and checking the movement (hmmm… door is a bit squeaky, may need scraping down…) once everything was in place the tops could be glues in place the the capillary glue run allong all edges. The box is finally complete :).