• Coffee Table
  • Day 1
  • Day 2
  • Day 3
  • Day 4
  • Day 5
  • Day 6
  • Day 7
  • Day 8
  • Day 9
  • Day 10
  • Conclusion
• Whiteboard

Day 5

Prototype setup and testing

Once the unfiltered CCD camera lens finally arrived and installed it and focused the camera before using some blu-tac to attach the Long Pass filter to the end of it. I tweaked the camera's positioning and configuration settings for quite some time until I was able to get the camera viewing all of the projected screen area without seeing the edges of the mirror (which is what the bright white spot is at the top of most of the filter comparison shots). I managed to calibrate the system and after a bit of playing around found that my machine was slow and that I still hadn't quite got the hang of calibrating it, either making it too sensitive that it began sensing my fingers while I was trying to keep them off the screen or so dull that is missed when I wanted it to pick up my fingertips. Below is a video of the final prototype in action with a few apps available from around the NUI Group website and from around the web.

Investigation of Materials for the Final Design

One of my trips through the local hardware store I decided to investigate materials that they might have that would be of some use for the final coffee table design. Having not undertaken a welding project before the prospect of making a welded frame was not a welcoming one, plus the need to cut all the materials to length with the correct mitre on the ends or contour cut out for a reasonable join and symmetric frame. I decided to look into using extruded aluminium and bolt the whole thing together which also posed much the same problems without the need to weld. While looking through the extruded aluminium I found that nothing was quite to my needs, I almost purchased some however I decided to go for a browse through the rest of the store. I came across chrome plated steel tubing in the bathroom section of the store... it was about the same prices as the aluminium except it felt far stronger and being chrome plated looked far better. I grabbed a few pieces and stumbled upon the copper plumbing fittings and decided that I was going to build the frame out of tubular steel and copper Tee pieces.

The Tee pieces would eliminate the need to weld and the need to mitre or contour the ends of the tubes. The fittings went on nice and tight and really didn't want to come off in a hurry so there would be no need to weld the frame together. Lastly they could be cut using a plumbing tube/pipe cutter which gives far cleaner and more accurate cuts than I could hope to achieve with a hacksaw or drop saw. The chrome tubing was designed to be used for towel rails and possibly hand rails I could see no reason it couldn't hold up a huge piece of glass the weakest part would probably be the copper Tee sections however they were also quite strong. I purchased only one 900mm length and a few mounting plates to use for measurements and went home to draw out some plans.

The tubing comes in standard lengths of 900mm, 1200mm, 1600mm and 1800mm. My original concept (at the top of this page) was designed inside 2m per side regular triangle so it used none of these lengths. After trying a few iterations of the design I found that either the frame would be too wide for my liking or not long enough for the projector to sit where it needed to using these standard sizes. I already knew if I used this approach that I would have to cut some of the tubing to size for the legs so I decided to try a few half standard lengths. Thus I came upon the sizes of 1200mm and 450mm sides, one 900 made two cross connects on a short side and two separate 1200mm pieces for the long side. One 900mm piece could be cut in half and then further cut to produce two leg sections. I also managed to tweak it so that the gap between the second set of legs where the mirror bottom would mount came to 1600mm which would help retain the shape of the overall frame and make for an easier time of mounting.

I returned to the hardware store and purchased a tube/pipe cutter, 4 copper Tee fittings and two 1200mm lengths of tubing with which I tested to see how well the tube/pipe cutter worked on the chrome plated steel (since it wasn't rated for steel) as well as how tight the copper Tee pieces fitted on the tubing. I made the two front horizontal cross pieces and cut the 900mm into the sections for the two front legs and was very happy with the result. I then jumped into Cinema 4D again but this time constructing the frame out of component pieces matching the specification that I had drawn out. This was both to check that my measurements were going to allow everything to fit and to make sure I knew which order I was going to construct the frame since the copper Tee pieces are such a tight fit it would be difficult to change angles once things were all knocked into place.