Sounds like either SheetCAM or the import program is in the wrong "units" (inches VS mm) or there is a problem on the import side..
Make sure you have SheetCAM set to the same units as your Dynatorch software. Look at the G-code you get from SheetCAM. Are the numbers crazy? If they are what they should be, then there is nothing wrong with SheetCAM. You may have a format problem (they way the numbers are formatted with leading zeros maybe). The whole key is what the G-code looks like. The WAY the g-code is formatted is controlled by the POST processor in SheetCAM. Especially important is the way the arcs are handled in the G02 and G03 sequence between different controllers.