The .LC extension means you have saved this file as a lazycam file. This is fine when you want to pick it up and do more work on it. To get a .TAP file of Gcode for Mach3 to run you will need to hit the 'Post Code' button at the top right of the Lazycam screen. When you get more into it you might explore posting options, but for now I hope this helps.

Cheers.

BTW I am currently using a Kress spindle with a relay for Mach 3 to switch it on and off. I have a Super-PID on my bench which I hope to fit soon. I plan to photo diary the project.