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Discussion Starter · #1 ·
Like a lot of folks here I'm gathering info in preparation of building my HT.


One question I have is that I want to have a perforated screen ( yes I know there will always be a debate on the pros and cons on this one ) and was wondering on the size of the actual holes in the screen and whether the holes are all over or just in the required location of the material where the speaker would be.


I have the facility at my company to have as many holes made to what ever diameter I want; in what ever location is correct; or even to vary the hole diameters if that is preferable.


These would be laser drilled so producing good sharp holes with no deformation or burn and all done in the blik of an eye. I guess by definition it wouldn't be "DIY" but the next closest thing.


I guess my next question would be if any body out there has any experience on this angle or whether you guys think it's all worth while ( as oposed to just going and buying a perf screen )


Taff
 

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Taff,


The entire screen is perfed, not just the area in front of the speaker(s).


From the Stewart Filmscreen website:
Quote:
Perforations Per Square Foot: 30,000

Hole Size: .020th of an Inch in Diameter
Stewart Filmscreen MicroPerf Specs


Exactly what type of machine do you have and can it really meet these specs? Just curious...
 

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Discussion Starter · #3 ·
Chip


It would be one of the laser drill set ups at my work. It would probably be done on a CO2 industrial ( automotive size ) stage. There would simply need to have the programme made for the hole pattern and dimensions.


Not sure though at this point whether the stage could handle a 10' screen

to enable holes to be made ove the entire area.


I guess I'll have to have a deeper look into this


Taff
 

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Have you guys considered using the same cloth that is used for cross stictching? I found some in 48" inch width (probably 46" usable width) and the hole pattern looks exactly like that in the Draper perfed screens. Thin out some paint (or Screen Goo) and spray it on, and you may very well have a Draper-like perfed screen.


Sam
 

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Chip:


As you can see, for a normal screen (say 100"x56") you're talking about 1.2 million holes. Stewart uses a punch machine to do their holes, and they do them better than anyone (IMHO)...much better. For what it's worth, a perf screen from Stewart is basically 2x the cost of a non-perf screen...I just can't imagine you'd want to try something so complex (with so many things that could go horribly wrong) for a one-off solution.
 

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Discussion Starter · #6 ·
Alex,


It wouldn't be too much of a task to get the screen drilkled by the laser; just a matter of getting one of the guys at work to make the programme. My guess is that to drill all them holes over that area would take about ten minutes max.


Actually 0.02" dia holes are quite large to the size we normally make.


Any way a question while I'm here..


Why does the screen have the holes all over the screen and not just over the area where the speaker would be placed behind.


Taff
 

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If you want a uniformly bright image, you need a uniformly perforated screen. Oh BTW, you are going to lose at least 10% of your image brightness due to the holes.


Commercial theater screens can lose 20% of their brightness because of the perfs.


Vern
 

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Ooops, I said Chip when I meant Taff...my bad.


Taff, I guess where I'm coming from is that your "test bed" (a plain screen) is going to be an expensive thing and one error can ruin it. For example, you could easily drop $1,500 on a non-perf'd Stewart screen--that's a pretty expensive blank to experiment on. I'm all for DIY stuff, but I think this type of DIY could very easily end up costing you MORE to accomplish than just buying the already perf'd screen. Even factoring out the time/cost of the machine, the risk adjusted success cost of the fabric alone would be enough to give me serious pause. I'm not saying it can't be done (in fact, I'm sure it can be done); I'm saying that *one* mistake would effectively render the cost savings of this DIY project moot. Neither you nor I have any idea what the kill rate is on this type of operation--I'm guessing that 100% yields aren't the norm here.


Vern is right--you'll have 10-11% light loss on the screen after perfing (assuming you stick to Stewart specs), and you want the entire surface perf'd to avoid hot spots.
 

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Discussion Starter · #9 ·
Thanks for all the feedback folks.


It's times like this that I ( we ) need to know when to file such ideas under the ... "good idea but !!" column.


I'd still like to go with a perf screen though. I think that a 10' screen 19'X26' ish room would work with the centers behind. I have total control over the ambient light and maybe I could afford some loss of gain. I'm thinking of the Sharp 9000 or the Seleco HT300.


Feel free to pass comment. Although I've been loitering with intent on this site for a long time I know there one heck of a lot more to learn than I already do. Any advice is welcome.


Taff
 

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Then again, it may be an interesting way for companies such as Stewart to create a perf'd Firehawk screen. (Last I remember there were problems with the mechanical machines with this fabric).


So there may be more possibilities to this thread!!!


A CO2 Laser may also be cheaper than the mechanical punch to run/maintain. (Or not...)
 

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Taff,


If you just buy the screen material without a frame it's much cheaper, also you can get some cheaper screen material (without frame again) and test your process before working on a final high quality fabric. Most screens are are made of PVC so you could expect similar results even if thicknesses and surface coatings are different. If it's not costing you anything personally to run the machines then it's pretty economical. Stewart's micro-perf fabric costs 2x more, at least!


I believe Stewart experimented with laser perforation when they were developing micro-perfs but didn't go with it for whatever reason. However, maybe it's time for someone to try again.


Good Luck,


Kam Fung
 

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Umm..


Wouldn't it be a bad idea to shoot a laser into a retro-reflective screen materal? Mabye that's why they use a mechanical process...
 

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Quote:
Originally posted by snowmoon
Umm..


Wouldn't it be a bad idea to shoot a laser into a retro-reflective screen materal? Mabye that's why they use a mechanical process...
A retro reflective material isn't a mirror.... it would absorb way enough energy from the CO2 laser to melt. And furthemore, since the reflected light would be scatered and not focused, it wouldn't be harmfull. (you still shouldn't look at the process without proper eye protection tho.... )


CO2 Lasers are also used to engrave metal sheets.... these sometimes are far more reflective than your screen ^_^


Pierre
 

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taff


being the steadfast tight wad that I am... I think it's a grand idea. There are sources for cheap screen material, you just have to look. As for the pattern to program, That seems like it should be a cake walk for your tech guys.


I'd say go for it!


Eric
 
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