Graphtec FC8600 cant hold calibration

[Bigfoot Graphix 0]

my fc8600 was just recalibrated to be spot on for cut lines less than a week ago, and its already drifting off by over an 1/8th inch. Is this common for these or is something going out on me?

[MZ SKEETER 4,708]

I own a FC7000-75 and a FC8000-75  never had a problem with cutting/tracking on either one.  I put my pinch rollers in  about 1.5 from vinyl edge and always prefeed my vinyl the amount of my order. I only use 50 yd rolls of sign vinyl.  My niche' is large/and long detailed designs. For something long and really straight, like a long set of stripes, I put my pinch rollers all the way, locked down.   I don't ever have problems with my design not cutting correctly. My cutting software is Flexistarter. 8.6 and Flexistarter 10.  I don't really understand what you are calling a problem.  The cutter is not going to start cutting at the X Y point. X Y is only the start of measurement. My cutter my travel 3-4 feet before it starts cutting, on long designs. but if comes back to the front to finish them. Cutters start the cut where the design was first created at. (I also have my media sensor and pinch roller sensors off). I also may have my speed slower than you.  I am not going to some race,  I answer questions here while cutting,  I have never had my speed over 6. I have never needed to run fast. Most people use the overcut in their cutting software for lines to be spot on connected.. Perfect cuts start with the the correct blade depth.  Too many people see to use a credit card or post it notes to set their blade depth and this is just wrong and about too much blade exposed out of the blade holder. Too much blade out of the blade holder will cause lines not meeting. You only cut with the very tip of the blade. This is posted hundreds of times on here and works. Too much blade will also cause your vinyl to move, and drift over. 

To start with, you should set your blade depth correctly, by taking the blade holder out of the machine, and firmly cut across a piece of scrap vinyl, you will be cutting. You should only be cutting the vinyl and barely a mark on wax paper backing, Adjust blade to get there, Then put the blade holder back in machine, and use the force of the machine to get there, same results, only cutting the vinyl and barely a mark in wax paper backing. You should barely see and feel the blade tip out of the blade holder. Regular sign vinyl is only 2-3 mil thick. You only cut with the very tip of the blade. When you think the blade is so far in the blade holder, that you think it would not even cut, that is probably correct. 

[Bigfoot Graphix 0]

What I’m saying is that I do a lot of contour cut work and instead of cutting on the line it’s supposed to cut on it has gone back to cutting offset of that. The reason this bothers me is it was just calibrated and cutting perfectly. So this is cutting into my printed graphic and leaving raw vinyl in places because it’s also causing it to cut onto unprinted spaces

[MZ SKEETER 4,708]

I don't do any contour cutting. Can't help with that. only make sure your blade depth is set correctly so that it doesn't drag your printed design. Same way as I explained above. 

[MZ SKEETER 4,708]

This thread is on a CE6000, but is it anything similar to what you are getting?  Part of his problem was the resolution, ( Steps). as well as his carriage was loose a little bit. And blade depth.