So I bought another £2 balsa wood bundle from my local model shop to see if I could improve on the original.
The first thought was to make the internal structure stronger - so I used 4 (not 2) struts inside the tower and used thicker balsa at the rear and the front. Having 2 struts at the front of the tower meant that the exit is much smaller than the original - but looks neater as well.
So I start with two 3" wide and 9" long 'chunky' pieces of balsa - these are the front and back of the tower. To these I glue two 9" x 1/2"struts - note that these are slightly indented to allow the sides to be glued to them later.
On the 'front' I cut out a hole roughly 2" x 2" at the base - this is the exit hole for the dice (see below).
I then take two thin strips of balsa - 9" x 1.5" - to slide between the struts on the front and back. The One at the front must have 2" cut off its length obviously (or it will block the exit ramp).
The sliders will have the jigglers stuck to them. I experimented by using plasticard strips but these proved too fragile when bent - but would come in useful later. So I went back to using thick card instead.
The slider fits nicely inside the struts - allowing a bit of flexibility in movement.
As mentioned, I tried plasticard for the jigglers. However, when scored and bent they soon broke so I abandoned that idea and went back to thick card. The idea of the card jigglers is to create 2-3 triangles which (with the addition of a bit of card - or in this case dicarded platicard) create overhangs so the dice tumble and roll as they come down the tower.
The card is cut into strips the same width as the sliders but a longer length. Originally I tried one long strip but it seems better to cut 10cm strips and use as follows.
Measure out lines at 2cm, 5cm and 8cm on each 10cm strip. Score and bend at 2cm and 8cm, ensuring that you score and bend on the opposite side of the card on the 5cm line. If done correctly (some trial and error here) you will end up with a shape like this : _/\_ The flat pieces are stuck to the slider and the triangle is your 'jiggler'. I anchored each piece with a matchstick at each end against which the flat pieces were stuck down.
The key to this is staggering the jigglers exactly (otherwise the dice will get stuck inside). If you use large dice, you'll need a bigger tower OR have your jigglers at a flatter angle. For my 1.2cm dice the configuration seems to be OK and my larger 1.6cm dice only one gets stuck occasionally. As I say - trial and error!
The easiest way to do this is to lay your sliders side by side and line them up so one jiggler is exactly inbetween the space between the other sides jiggler - the optimum position.
Once happy with the positioning, It's time to extend your jigglers. Using card or plsaticard, cut a piece the same width but a bit longer than the downward angled / of the jiggler. You can see this in the picture above - the black pieces are plasticard stuck to the card jiggler which in turn is stuck to the slider. I used matchsticks to provide additional ancoring (you can see it between the black and red plasticard) - just a bit of extra support.
In the picture above you can also see the exit ramp. This has to be attached to the 'long' slider (i.e. the one that is attached to the back. The green stick you see is positioned to provide added strength to the ramp jiggler.
Here you can see both completed sliders. Note that the two sets are staggered so the dice should fall from one to another. I put the two together (before gluing) and threw some dice down and found some got snagged up. I therefore reduced the length of each one until the dice fell freely. As long as there is some degree of overhang, you should be OK.
The red bits are just plasticard left over which I just used to neaten them up and give something for the cloth (see below) to be stuck to.
We now turn to the exit ramp. This must be much longer than a normal piece of card stuck to a jiggler and be at a steep enough angle to let the dice roll out freely. As it's longer, it needs more anchoring - I've used 2 coffee stirrers cut to size - two stuck to the struts and the third between those two to provide added strength. The ramp as shown was too long - it needs to be cut flush to the base.
You can also see that I've covered the card on the jigglers in a thin cloth (from some cheap dusters). This is to quieten the sound (the MkI is quite noisy) and in practice provides a lovely muted rattle - very pleasing on the ears!.
All cards inside were similarly covered, including the exit ramp and the landing area (of more later).
Here you can see the ramp piece now cut to size before covering in cloth. As in the pictures above you'll also see that one side has been attached - a thin 3" x 9" piece - to the back piece. The front has also had its side attached (out of picture) on the opposite side - so the two slide together to form a box - with the ramp peeping out of the exit hole (if you've done it properly).
But before gluing together there was something else I wanted to do. The MKI occasionally saw the odd small dice get stuck - usually on the side. In addition (as mentioned before) it was a bit noisy. By cutting insulation foam to size and shape, it provides three solutions - it prevents small dice falling off the jigglers and in between the struts, it keeps the dice rolling quieter and it provides a bit more internal strength to the structure.
You can also see the jobs the green stick and coffee stirrers are doing in supporting the ramp jiggler.
Then came the gluing. Essentially glue is placed between the struts and edge where no side has yet been attached (on the front and back). Once glue is placed, the two halves are joined together and - if you've done it right, they fit flush and the jigglers are properly staggered and the ramp pops out at the exit hole. I was lucky enough to do this first time. I found that when stuck together some dice got trapped but there was enought flex in the glue on the front slider to allow a bit of movement (upwards) to create a bigger gap and allow the dice through. I certainly recommend putting the two sides together and trying it out with some dice before gluing!
I then put rubber bands around the tower to hold it in place while the glue dried.
While that was drying, I turned to the landing area. This is a 4" x 9" thin piece of balsa. On both long edges (leaving a small gap at the end away from the tower) I glued two 9" x 0.5" struts. These provide something to attach the tower to AND stop the dice escaping from the landing area. At the far end (flush to the end of the struts and the base) I glued a 4" x 1.5" balsa piece as a backboard (against which some dice will bounce and then return to the landing area.
While the glue on the struts was still wet I placed the tower to ensure it had enough space to sit. I then glued the sides of the struts (and some of the baseboard) against which the tower would rest. More rubber bands were hooked around the struts (including the small overhang at the back (see above) to keep it all in place while the glue dried.
As you can see, the baseboard is bare and the struts just about keep the dice in check. I therefore glued two more struts over these to provide more strength and to provide a deeper landing area. These were glued and rubber banded as before. Once in place I knocked in 4 small nails - two into the backboard to attach it more firmly to the top strut and one on each side to attach the top strut more firmly to the tower. The end result is a much more solid construction than the MKI.
For the top I cut a 3" x 3.5" piece of balsa which fit flush to the tower - giving it a neater appearance.
The final touch was using the same duster cloth to cover the baseboard to provide a softer, quieter landing for the dice.
And here is the finished article (alongside the MkI).
And on its own. Neater, better, quieter, stronger.
Vorspung durch technik!