Cutting out thin letters successfully? Anyone?

Okay, so I posted about my issues with the 1/16th bits not cutting deep enough and I think I found a solution to that problem thanks to you guys, but I still cannot get thin letters to cut out without breaking. I am using 1/4 inch plywood and I have slowed the bit down to 70% of the recommended speed and when the cut gets down to the last 2 or 3 passes, the wood snaps and destroys the cut.
I have tried standing there and holding a ruler over the letters to try and stabilize them, I have played with the tabs, and nothing works. What am I doing wrong??

I recommend using lots of tabs to keep the letters from moving about during the carve.

I also recommend using the tape and glue method of holding. This is where you apply tape all over your spoil board, tape all over the back of your workpiece and then glue all of it together prior to the carve. This should keep your letters from moving around and keep them from being lifted by the motion of the bit.

As Harry said. If cutting right the way through you need to tape and glue or use double sided tape to hold the work piece down.