I agree with @JaVelin that this is probably your problem. What you do to fix it depends on which tool you use to create the G-Code file. However, it’s very easy to add this manually to the existing G-Code file with a text editor.
Open the G-Code file and search for M3 codes. This it the command that starts the arc. After the arc is started, you want to add a delay before the code to start moving. Therefore, add a line after each M3 line that has “G4 P450”. This creates a 450mS dwell.
NOTE: this is 450mS ONLY if Mach3 is configured to use milliseconds for dwell. If this is not the case, then this command will delay for 450 seconds and you will burn out your workpiece, your cutting tip, and quite possibly your Plasma Cutter electronics. I highly recommend that you make a test run before you turn on your cutter!
How to change this is documented recently in this forum and would be a simple search.
You have to switch Mach3 over to milliseconds. Search “milliseconds” in this forum and there is plenty of directions on how to do it. You will get cuts skipping areas intermittently if you don’t. It is a windows /Mach3 glitch.
Also remember with our 625 ex machines Miller only makes drag tips, they do not make machine tips so you have to run the tips .032 off the deck to get a good cut,
I use a feeler gauge to set the height.
There is also a green loctite that is designed to be used on fasteners that are already assembled so you don’t have to unscrew your setscrews and possibly create another potential loosening situation. It wicks through the threads of a fastener that’s already bolted in and is similar in strength to the blue type.
@jamesdhatch is absolutely correct about the green version of Loctite. If you want something locked down, the green stuff will do it and, as he points out, will wick into the smallest crevices. Just be very careful that you don’t accidentally let this leak into a place you might want to adjust or have to move again - it won’t. DAMHIKT!
Along with all of the other great suggestions, make sure that the set screw is aligned on the flat part of the motor shaft. Ask me how I know there is a flat spot, lol I missed it when I originally put it together.
Well, the fact that the pattern is returning to its origin indicates that the axis are probably not slipping, losing count, or anything else that would distort the movement permanently.
That the left side is cut through and the right side is not probably indicates a small tilt in the torch (the tree ‘ziggies’ cut correctly when approaching from one direction but not the other). Finally, the small circles are almost cut out, but not quite so the dwell helped but not enough so… increase the dwell but not too much.
I have found with the Miller 625, when your not cutting through the heat is blowing back to the torch and you are eating your consumables up fast. When I am not piercing thoroughly I stop the run and figure out why as fast as I can.
If you have not changed your swirl ring recently do it asap. They last a long time but when they are not working 100% your torch will do some funky stuff. For $12 it can save you a bunch of cash in tips shields and headaches. I had my 626 for 2 years before I changed it and it solve a bunch of strange troubles.