Scaling issues can be quite common and vary from cutter to cutter or program to program. I would suggest using the pen tool to dial in the scaling and you'll also want to have a ruler handy so you can measure out the dimensions. In SCALP the first thing you'll want to is make a 1"x1" square and cut that out. Measure the square and determine by how how much it is off. Once you have an idea of the variance you can now begin scaling it properly. Go to Cut with Cutter the icon with the Paper and Scissors. That will open up the preview window and from there you will click on the Settings tab. A new window will pop up and in that window in the top left hand corner you should see X and Y Resolution. Make sure the units are set to inches. Most of the time these will be set to 1.00 and 1.00. So now you will adjust these numbers accordingly in order to resolve the scaling issue. For example: If you 1"x1" square measures 3/4"x3/4" when you cut it out, you will want to INCREASE those numbers by .250. So now you're X and Y Resolution should be at 1.250. Of course this will vary from person to person as far as how much your resolution is off but this will help dial it in as close as possible. You may have to do this a few times to get it close. If you notice this happening on larger projects you may need to scale your starting square up to a larger size.