Having set up Auto Save and subsequently lost some work due to an unexplained crash I thought that my work would have been saved. Initially despite my best efforts I was unable to locate the backup and sadly had to recreate the work.
On reading an earlier post on this subject with another version of TurboCAD I took the clues from another contributor and tracked the file to a directory at the following path: Library/Application Support/com.imsi.turbocaddsnESD/TC Backup.
I also read that other contributors thought that it would be helpful to move the directory to an alternative more simple location but quite rightly was advised that this was not a good idea.
My suggestion is that a link to the directory is created in the sidebar in Finder. This is easily done when the directory is located by going to File and in the list is the option to add to Sidebar. The link can easily be renamed and a simple click will find the backup files immediately.
To set up the backup check out TurboCAD preference and then Filing.
Hope this might help others.