X axis belt - how tight

I replaced the belt a couple of weeks back and it is mostly OK but getting occasional skips that ruin a full half hour cut. I can see where too tight would be as it would stick the screws into the belt, but how tight is tight enough?

Belt tightness is always a debated topic. In my experience, if I start experiencing skips, I just tighten the belt a bit.

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If it’s skipping by a tooth profile distance, it’s way too loose. If it’s loose enough to skip a tooth, you are probably also getting some backlash.

If it’s shifting by different distances that aren’t an even multiple of the belt pitch distance, you might instead be skipping steps. This could happen from the belt being so tight that it substantially increases resistance such that it sometimes is greater than the torque provided by the stepper.

(I’m not an expert here, but I think you should be able to see backlash by engraving a circle and seeing how well the ends meet. If you single-pass engrave a pattern like |◯| and the two | lines are the right distance apart, but the has a visible join where it starts and stops, that’s probably backlash. I’ve done similar tests on a 3D printer when I’ve suspected backlash.)