Most likely just a setting which was missed. Sorry you have had trouble this is frustrating. Many times in the past sometimes a person got on a machine and changed a parameter. Not changing it back the next guy on the machine would end up with a bad part first run. We would compare two machines in the parameters settings and match them.
It solved the problem. Can you get anyone to copy their settings off of their working machine identical?
If you've tried everything sounds like it's time to call Fryer. Maybe you have done this and found they are not helpful. If you haven't it's worth a try. Sometimes I'm pleasantly surprised at the help I reveive.
ok, I wanted to get back to this in case somewhere someday someone has the same issue I do.
This seems to be a bug in the 840D / SL machine.
The machine has two buttons. Cycle start and spindle on and off.
When you program the thread program you should just be able to back the tool off and hit cycle start. The machine starts up and goes to town.
However, if you do this, the feed rate runs at some multiple of your rapid based on what your feed overdrive is set to. Obviously it shouldn't do this but it does.
I stumbled upon the fix just by pure dumb luck after two days of pushing every button I could.
If you start the spindle first , and then push cycle start, somehow someway, the feedrate is actually accepted from the program and it will cut the correct thread.
I have no clue why. Its obviously a bug in the machine or firmware or something. Maybe this will help someone else someday.