3 ways how you can hack your tab tensioned projection screen for better performance
OK, I am going to start out with a disclaimer here. You shouldn't do any of the things I suggest here, if your screen is performing fine. If you are happy with the way it is, so not touch it. Secondly, only start hacking your projection screen if all else has failed.
If you have a problem with your screen, first try to get it resolved by a repair under warranty.
However, if you no longer have any warranty or you bought the screen as a second hand bargain, then there's help when you screen fabric is no longer perfectly flat.
Let's start with the basics:
1. Adjusting the tab tensioning settings
A tab tensioned projection screen works with lateral tension. This is tension coming from an elastic rope that runs along the screen in the vertical direction. This rope runs through pockets sewn to the main fabric. These pockets are the "tabs" in tab tension. These elastic wires are connected to the tube in the housing of the screen and to the lower bar of the screen. On the lower bar are screws that allow you to increase or reduce the tension.
By reducing the cord length, you are increasing the tension. By increasing the cord length, you are reducing the tension.
Now, you might think that when you see wrinkles, you need to increase the tension. Not necessarily. The trick so to create maximum tension, but evenly enough. Uneven tension causes wrinkles. So when increasing the tension does not work, try reducing it. It can be a delicate process, so take your time and test. That's the only way to get the best result.
But what if that doesn't work?
2. Increase the weight of the lower bar.
Tension isn't only created in a horizontal direction. Gravity pulls the screen down too. By adding weight to the lower bar, you can increase this tension in the vertical direction.
How can you achieve this? Well, the sides of the lower bar have the tensioning adjustments. These can be taken out of the lower bar. Do this carefully. You can then see the lower bar, which is hollow (otherwise there would be no way to get the screen fabric into it). Often there's some spare space. Either next to the fabric or in a different chamber in the extrusion (when your lower bar is made of aluminium). Insert a thin rod along the whole length of the fabric to increase the weight.
Make sure that the rod is blunt, otherwise it will tear into the screen fabric when you push it in. Use a lubricant to make things easier.
You should see results from this. If not, you could benefit from an uneven weight distribution
3. Selectively increase the weight of the lower bar
In simple terms, this means, add weight only to certain spots to remove wrinkles or V-shapes. This is done by trial and error. In practice, this means cutting up a rod and using another rod to push a certain length in position. When you see wrinkles disappear, it's in the right spot. If nothing happens, try again. With a different position or a different amount of weight.
If you still don't see any difference, it's a lost case.
When selecting weight for the lower bar, keep this in mind:
1. The bigger the screen, the more weight you will need
2. Go for materials with a high mass. There's limited space, so you need the maximum weight you can get into that space.
Good luck,
Otto Tromm
