I’m getting poor cutting results on the extreme left and extreme right hand side of my bed (outer quarter on both sides). The middle portion seems to be fine. My mirror alignment also seems to be ok. Am I correct in assuming that perhaps my bed is ‘sagging’ in the middle and the sides are higher, thereby resulting in this? Thanks in advance.
The easiest way to test if you bed is not even is to move the head of your laser about in the working area and measure from the cone to the top of the bed in various places. Perhaps your laser came with a focus height “tool” usually a bit of plastic that you can use to determine your laser heads height, this would be especially useful to do if you generally use an auto-focus system.
If you bed is absolutely level, then I’d suspect that your alignment needs attention, perhaps the alignment from the final mirror (mirror 3 usually) in the head of your laser, but without a lot more info on your system, I’m making some very broad guesses.
Here is a quick alignment check that is super useful to do.
and a check of the alignment downward through your lens: