Serrated cut lines?

Sounds like the theta belt that turns the toolhead has lost some of its teeth and then, as a result the home position for the blade has also shifted. The blade then is constantly at the wrong position for a tangential cutter to provide a clean cut.

The solution is to replace the belt and reset the home position of the blade. It's a fairly common repair for Gerber tangential plotters.

 

maybe check for a worn out platen... could have a groove worn in it so the blad's not contacting the vinyl evenly

 

Turn the plotter off and back on and check the position of the blade after it does its homing routine. It should be in position to cut a horizontal line on the X-axis. If it's well homed, then look for excessive slop in the gear belt, a chipped blade, a loose blade, or a blade not fully seated in the tool holder. It is also possible to install a blade backwards in which case the tip would not be in the center.

 

Rotate the black shaft on the feed in side of the plotter that lifts and lowers the tool head to check for unobstructed contact when down and adequate clearance when up. When down look for about 1/10th" clearance between the lifting fork and the contact point with the tool holder. When up look for 1/10" or so between the blade point and the X-axis drum.

Do you have a teflon theta washer on the tool holder? When was the last time you lubed the throwout bearing inside the toolhead? It should get one drop of oil every six months.

 

Did you check the position when first turned on? The blade should home to that you can lower the blade and slew to the left and get a clean cut from an x-axis move. Try in with a piece of vinyl.

 

Yes that's as it should be. There is a black bar on the feed in side of the plotter that rotates to physically lower or lift the toolholder in the toolhead.

That the blade appears parallel to the sprockets is correct. If turn off the plotter while in that position and lower the blade by rotating the black bar you can then manually move the x-axis drum towards the feed out side with some vinyl in the plotter. You can then inspect the cut. If it is free of serrations then the problem most likely is not related to the initial homing of the plotter when you turn it on.

By eliminating this you narrow it down to 1) a malfunction that is happening most likely in the theta rotation of the toolholder, 2) the condition of the blade or 3) a bind somewhere in the mechanism ... usually from dirt & debris and/or a lack of lubrication.