The compliant surface didn't end up as a nice smooth surface. There is a bit of streaking due to the silicone not leveling itself out very well. I believe this was probably due to me taking too long to smooth it out. However, the camera can now pick up my fingertip touches very well through the rosco projection screen without me having to use much pressure.
One problem I'm seeing is a ghosting effect where the trails of my fingertip movements are staying on the screen. I'm hoping that this is due to the silicone having not finished curing all the way yet. I need to do some research into this effect to see if there is anything I can do about it.
The other problem that I'm afraid I'm going to have is a poor image quality when I hook this up to a projector. The surface is visibly not smooth and reflects light a bit differently in spots. It is very possible that it will look fine, but I think I'll end up with spots that are brighter/darker than others. (Not that big of a deal if the touch screen works well..)
I have plenty of silicone left if I want to give it another shot. Plus there is another method I read about for applying this stuff that allows you to use much cheaper silicone along with a paint roller. Sounds like it is MUCH easier to get right then the method I used, so I might give that a try if the current surface doesn't work out.
Sorry, no pictures. Considering the acrylic and silicone are both clear, the pictures I took really don't show anything that you can't see in the previous pictures.
Now it is time to build the frame. I have come up with a design that will make the height and angle of the table adjustable, so the exact projector placement doesn't have to be known in advance. (I keep forgetting to bring the work projector home to try out and it gets used a good bit, so I don't want to accidentally leave it at home after borrowing it...)
Once the frame is done I'll probably just take it to work to finish rather than bringing the projector home... maybe...
Sunday, October 26, 2008
Saturday, October 25, 2008
Sorta Clear 40 - Compliant Surface
Well, I've finally got back to working on the Multi Touch table. Today I attempted to add the compliant surface to my Acrylic. This is supposed to make it so that a much lighter touch is needed to trigger the FTIR affect.
Prior to this I was able to achieve FTIR with fairly light touch when touching the acrylic directly, but required a very hard touch to trigger when I had the Rosco Grey on the acrylic. The compliant surface will sit between the acrylic and the Rosco Grey and hopefully allow the light touch to work thorough the Rosco.
To prepare the acrylic for the compliant surface I cleaned it with rubbing alcohol and then added masking tape to oposite sides of the acrylic on the very edge. I made the edge seven pieces of tape thick which I think ended up being about .5mm thick. The tape edges allow me to run a straight edge down the acrylic to set the thickness of the compliant surface equal all across the table.
The compliant surface I'm using is the Sorta Clear 40, which comes as a thick silicone and a thin hardening agent. I mixed up about a 1/2 pound of the stuff using the specified 1 to 10 ratio of hardening agent to silocone.
I ended up with quite a bit extra material being mixed and just let it spill over the edge while flattening it all out.
I ended up having issues with it not looking perfectly smooth after I finished, probably due to the fact that the straight edge I was using was made out of wood instead of metal and was just barely long enough to reach between the raised edges. I have the acrylic covered now to keep dust and cat hair from settling on it while it cures. Hopefully it will settle into a smooth flat surface over the next few hours.
I'll put up some before and after shots of the acrylic when it is finished curing. (Claims to cure in 60 minutes, but I'll probably wait until later tonight or tomorrow, just to make sure.)
If this works as advertised then I'll just have the frame left to build, which I sketched out a few days ago. So I just need to buy some more wood and a bit of hardware for the table and I should be done with the physical aspect of it. It looks like the open source software that will run this has seen quite a few improvements since I started, so hopefully the software aspect of the table will be pretty simple.
Prior to this I was able to achieve FTIR with fairly light touch when touching the acrylic directly, but required a very hard touch to trigger when I had the Rosco Grey on the acrylic. The compliant surface will sit between the acrylic and the Rosco Grey and hopefully allow the light touch to work thorough the Rosco.
To prepare the acrylic for the compliant surface I cleaned it with rubbing alcohol and then added masking tape to oposite sides of the acrylic on the very edge. I made the edge seven pieces of tape thick which I think ended up being about .5mm thick. The tape edges allow me to run a straight edge down the acrylic to set the thickness of the compliant surface equal all across the table.
The compliant surface I'm using is the Sorta Clear 40, which comes as a thick silicone and a thin hardening agent. I mixed up about a 1/2 pound of the stuff using the specified 1 to 10 ratio of hardening agent to silocone.
I ended up with quite a bit extra material being mixed and just let it spill over the edge while flattening it all out.
I ended up having issues with it not looking perfectly smooth after I finished, probably due to the fact that the straight edge I was using was made out of wood instead of metal and was just barely long enough to reach between the raised edges. I have the acrylic covered now to keep dust and cat hair from settling on it while it cures. Hopefully it will settle into a smooth flat surface over the next few hours.
I'll put up some before and after shots of the acrylic when it is finished curing. (Claims to cure in 60 minutes, but I'll probably wait until later tonight or tomorrow, just to make sure.)
If this works as advertised then I'll just have the frame left to build, which I sketched out a few days ago. So I just need to buy some more wood and a bit of hardware for the table and I should be done with the physical aspect of it. It looks like the open source software that will run this has seen quite a few improvements since I started, so hopefully the software aspect of the table will be pretty simple.
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