I have re-uploaded my STL file a couple of times, and each time, your system changes it dimensions. For instance the original height of my design is 8 inches but when it shows up in "my models" it shows up as 20 plus inches. What's up?
The dimensions at SW were inches 2.74 x 2.93 x 20.32.( I am a psychic). Scale it .3937(1/2.54) and upload as inch. Somehow the model was scaled by 2.54 which is a conversion of inches to cm.
You can use both Meshlab and Netfabb to determine basic dimensions which then scale if needed to coincide with the upload values you can choose for the size of the print . With trial and error you can usually determine the workflow needed for properly scaled,upload values to SW.
KeithHave any questions regarding Blender, and need fast answers, you are always welcome at the IRC Server Freenode, channel #blender. As a bonus, several there have experience in modelling for 3D prints.