On Tarkin last night I cut these circles and I get this gap/offset where the cut starts/ends
Is this a settings problem or an alignment problem?
Can this be fixed in my cut settings?
Dorian did this as well but much less so (but still noticeable.
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Thanks for being proactive about posting this… because I saw something similar earlier this week and then forgot to post. 
I’m curious about the scale and speed at which you observed this result. I had it set to moving fairly fast at a small scale – just scoring a hairline circle with 25mm diameter onto baltic birch with layer settings of 800mm/s. Since you were cutting, I’m presuming it was rather slower speed than that?
Anyway, see attached photos for the symptoms I observed – and a partially-formed hypothesis about at least one factor that contributes to the symptom.
Symptom: The one side of 25mm circles has a ~0.01mm “stretch” on the top hemisphere.
Hypothesis based on LB’s path preview: The notch represents a start/stop glitch, but possibly only when the start/stop point lies along a vertical tangent of an arc? I came to this guess based on observing that the lower two circles in my design came out perfectly – and those are the two where LB just happened to optimize the path such that the start/stop points are on a horizontal tangent of the circles. Note that my source vectors are perfectly clean circles (4 equal arc segments and closed). All of the circles are literally copies of each other – the only difference in the LB file is that they’ve been positioned and rotated differently.
Finally, just for reference, here’s the design and layer settings summary:
Oh, for good measure, I took a screenshot of LB’s optimization settings:
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3mm Acrylic - tarkin Cuts at 35/100, etch at 130/35
Circles are like 50-60mm
Gap didn’t seem to be entirely consistent but on Dorian it was at 3 and 9 o’clock
Mechanical issue with the X axis?
depending on which direction those circles were drawn, it looks like backlash in the x-axis drive
@dannym This issue seems to be a bit worse recently- we had similar problems when teaching Big Lasers yesterday.
For the record, between Noreyko’s reports and me looking back at other instances where I saw similar artifacts in more circles, I think my hypothesis of “only on vertical tangents” might not be solidly consistent. There might very well still be a case for “only at certain angles”, but not necessarily so clear that it points directly to X or Y axis issues.