Would any other touch sensors be viable to work with on a home project for example resistive, or is that likely to put oo much strain on the LCD?

I asked the suppliers to polish the edges after cutting. I’m not sure what method they used. The surface looked pretty smooth, though it was not completely “flat”, probably cut with being cut with a bandsaw. If it is laser-cut then you’d probably get a better finish.

A flat, highly polished surface is more important for FTIR designs, where you need as much internal reflection as possible. If you are using a DSI design (with Endlighten), its probably not that critical.

Are you sure you’ve got enough power to your LEDs? If you’re using the flex ribbon you’ll need at least a 2A at 12V. Check the data sheet for the power consumption per meter.

You site is a big help and thanks for answering our questions.

Did you polish the edges of the acrylic? If so, what method did you use?

I polished mine with 320 - 400 grit sand paper and then a buffing wheel on a drill.
It doesn’t have the same finish you would expect from something like flame polishing and I am afraid that it the way I will have to go.
I am just not getting the IR lights into the acrylic good enough.

Thanks again,
John

Here’s the part description from the invoice:

1 x Narrow Dimmable LED Ribbon Flex by the 5-meter reel
(InfraRed 850 nm) (irrf850-reel)

At the time, the cost was $177 plus freight.

The size of the acrylic depends on how you’re going to mount it. I ended up mounting the acrylic as the top surface of my box, so it rested on top of the four sides. I made it big enough for a 25mm border on all sides. Initially I was going to sandwich the panel between the endlighten and a separate smaller sheet of perspex, but in the end I supported the panel on a small ledge inside the box. An advantage of the “sandwich” idea is that the whole assembley is more-or-less self supporting, but if you include the driver board in the sandwich its quite a bit larger on the top side. Make sure you support the weight of the acrylic - don’t just rest it on top of the LCD or you’ll end up distorting or cracking it.

Hope this helps.

Thanks again,
John

Thanks
John

Impressed work!

I am curious if you put some IR LEDs in the table’s bottom, is that gonna make fiducial marker more clear?

Sorry for the lengthy delay - I’m finally getting back to my sadly neglected blog, and sorting comments from the spam.

The main cost is the Mac Mini. I don’t have exact costings, but here are some rough figures. Some things I bought locally (in Australian dollars), and others are in US dollars.

Monitor: LG W2252TQ-PFT ($AU 270)
Camera: Unibrain Fire-i (B/W, $US 150)
Lens: 2.5mm focal length ($AU 30)
Brain: Mac Mini ($AU 1000)
Cable: Firewire 9-pin to 6-pin ($AU 50)
IR Filter: 850nm IR pass ($AU 20)
Acrylic Panel: Endlighten 10mm ($AU 30)
IR illuminator: 850nm IR LED strip light (~2meters, $US 100)
Power Supply: 12V, for illuminator ($AU 30)

Assorted hardware: MDF, wood screws, nut/bolts, square dowell, 1″ aluminium angle, steel strip, T-nuts, hinge, construction adhesive, silicone sealant, magnetic catches, gaffa tape (~$AU 100)

Hope this helps.