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Ok, I just purchased a MH721 from uscutter. I could not get it to run straight at all. Bit of back ground. I have a roland pc60 and a pnc1000, the pnc 1000 has finally gave up for good, I ;ve had it since 1990. It also has issues with tracking but used all the tricks I've learned on the Rolands over the years and applied to the MH721 with NO LUCK AT ALL. I've also built my own CNC router table so I am not new to this stuff. So after trying everything with no luck I decided to check the carriage allignment ( top alluminum extrusion that the blade holder run on) with the knured drum that the pinch rollers run on. It was by more than a 1/6 of an inch causing the vinyl to always pull to one side. The fix. Open both sides loosen the belt on one side. You have to remove the stepper motor on the other side. There are 4 screws on each side that hold the carriage gantry extrusion to the end plates. If you loosen the screws you will see that that whole assemble can move. I had no calipers are precise measure tools with me SO I used a 24" level held agains the pinch roller wheels ( not lowered ) and adjusted the two side so that when looking down from the top at the edge of the platen where the knurled drum the distance between my straight edge ( 24" plastic carpenters level ) was as close as I could get by eye. I put everything back togather loaded some 24" vinyl. Now I can run about 10' and only run off about 3/16-1/4 before I did this I was off about 2". It's usable now.

Also have pinch rollers in the middle of the knurned drums cause it to deflect ( bend) and cause run off. I try to keep them as close as possible to the ends that are supported by bearing to minimize deflection.

I also allign my vinyl at about the half way point ov my cut, run it back and forth manually to check allignment and adjust if you have to.

I hope this helps some people on here. Some of you have gotten lucky with a plotter that was put togather with closer tollerances than others.For those that cant get tracking strsight no matter what check this out.

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Yep- Chinese low budget cutters do not quite have the QA standards of Roland or Graphtec- and this is also why they are priced much lower. The Chinese can be some silly little turds when putting these things together. I have even found mouse poop and chewed up wires on the inside of a new MH series cutter before. Glad you caught it, corrected it, and shared the solution!

Cheers!

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