Newbie here, looking for some assistance. I just received my Acmer P2, 33W and am trying to set up for a job I am doing for work. I’m using Lightburn and I’ve attempted etching a project from an .svg file and as a jpg file. The first pic is the jpg and the second is the svg. These were just test runs so ignore the wood but in each case things went well in portions and then something caused a shift or distortion. Pic 3 is what it should look like. I appreciate any suggestions.
That is called backlash. It is caused by loose pulley or coupling set (grub) screws. Get out the Allen wrench and tighten them all. Don’t stop when you find one loose.
Thank you, I’ll give it a try. Is this common on a new machine?
Yes, it is. Stuff shakes loose during shipment.
That’s not backlash, that’s losing steps.
Backlash is the play in the drive system. That thing is all over the place.
Did you hear a grinding noise during cutting? Was the laser head hitting anything?
I did not hear any grinding and the head was not hitting anything.
An additional problem: USB communication glitches trashing the G-Code commands moving the laser head.
These errors seem more common with higher-power lasers, due to the higher current drawn from what might be a marginal power supply.
One of the first steps is to get a USB cable with a ferrite core on each end, bought from a reputable supplier rather than the usual low-end Amazon / eBay seller of USB cables / beachware / lipstick. The USB cable packed with a new machine is typically the cheapest cable available and replacing it seems to produce more happiness than you’d think possible. 
To me that looks like a physical obstruction. check you have enough slack in your air hose and cable routing …
Thanks, I’ll investigate.
Pretty sure there were no restrictions but I’ll take a look after work. Thanks
Don’t take a look, check everything. Assume nothing is okay.
I check all belts and pulleys and swapped out the USB cable, also checked for any obstructions to the cables and air tube. I installed Lightburn on a different computer and tried a couple of different jpg files and still was not getting good results. The strange thing is that the first engraving I did well and then each one after that got progressively worse. I’m on a timeline so I sent it back and ordered something different.
Thanks to all for the help.
It was very likely a loose set screw on one or more shafts. That would explain why it got worse with use. It started snug and didn’t slip, but as it loosened up, the slippage got worse. I wouldn’t expect any better performance out of another machine. Manufacturing quality is sorely lacking on these machines in general.
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it’s helpful, if possible, to have the .lbrn2 file that you are using. We can examine that and ensure we know what you’re doing.
Makes a difference if you are scanning or running a vector, also the other values you use and scanning (if you’re scanning) along with top to bottom… does it start at the bottom and go up or top then down.
I don’t use USB with my Ruida as I get undependable data transfers and I blame that on the Ruida. However I use USB all the time with the fiber laser and cnc3018 I have, as there’s only a USB connection.
Contrary to most beliefs, USB work with differentiated data lines, meaning a change in state occurs when one data line goes high and the other goes low, respectively.
The USB chip differentiates it on transmit, the receiving chip integrates it back to it’s original state.
So, if everything is built correctly, it should be very dependable – at least the mode of communications.
Ferrite cores are used in the RFI and EMI roles. If you’re protecting from RFI, they need to be at both ends of the cable.
What really matters, according to the engineers, is the shielding of the cable and it’s connectors. One of the research groups advised the quality of cables was unpredictable even if they had ferrite cores on them.
They advised they had more consistency of good cables with the gold ended $30 or more cables. I would never pay that much and I have a ton of USB cables.
You might have poorly designed circuits, flaky connectors or a poor cable. You are limited to what you can change out. 
I agree with @thelmuth and think you have something like a grub screw that’s loose. Since we don’t know which is top or bottom or X/Y, we can only speculate.
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