Cutting Screen Protectors With The Silhouette

Update: Read the Summary

One of my aims when buying my Silhouette was to cut screen protectors. I'm sad to say it's not very good at this:

Oh, it can cut through the screen protector just fine. The problem is the force applied distorts the material, so the edges don't stick anymore (see how the edges have lifted up in the picture above. The square on the bottom left was cut with scissors). I tried fixing this by turning the screen protector upside down, so you cut on the sticky side. It still doesn't stick.

But I just got an idea - maybe I can use less force, but double or multiple cut? Haven't tried this yet.

Update 25 Feb 14
Ok I tried multiple cutting - up to 10 times - and it either distorts, or it doesn't cut through. Things left to try - double-sided cutting and 30° blade.

Update 15 Apr 14
I tried with a new blade. I could cut through the screen protector (after removing the TOP protective film) with about speed 8, force 15, blade 4, double cut, but it still distorts. I think using a hard cutting mat might reduce distortion, but there is a high risk of damaging the blade.

Update 23 May 14
Ok I've got the aluminium/aluminum Graphtec blade holder (CB09) and the 60° blades. Will probably make a whole post on them, but the good news is they CAN cut screen protectors without warping, barely:

That's a screen protector on my iPhone screen protector. The edges stick and there are no bubbles. This is one of the thinner screen protectors, and it didn't always work, so I'm not very confident, but at least it can be done.

Summary

ORIGINAL SILHOUETTE
The original Silhouette cannot cut through screen protectors without distorting them. It can still help, though. You should engrave the outline using as high a thickness as you can without distorting the protector (around 10), then finish off by hand using a penknife/X-acto knife. It's still faster and more accurate than ruler/freehand.

60° BLADES
If you want to, you can buy a third-party blade holder, which supports 60° blades (search for the CB09 blade holder). These CAN cut through screen protectors without distorting, but you have to search for the correct thickness (around 10-15), and use double cut.

ADVICE
If you're thinking of getting a Silhouette just to cut screen protectors, don't.
If you already have a Silhouette and would like to cut screen protectors, it's worth getting a 60° blade.