The upper Z-stop on the Precision Matthews mill has always been set somewhat awkwardly low. It had been set so that the hard upper stop left the table just below the furthest downward extension of the spindle quill. That sounds reasonable, but the safety is illusory, as it doesn’t prevent you from running the bit into the table or running the spindle into a vice, clamp, or your piece. Care and attention are always required when moving the table in any direction near the top of it’s range (which is where most work is done). And with the stop that low, you frequently had to lower the quill to bring your tool to the piece, sacrificing rigidity.
So I’ve raised the upper stop a little over an inch. Now, at the hard upper stop, the raised (default position) quill is just above the jaws of the Shars vises. I had hoped that this height would let users use the edge finder or the indicator at the soft upper stop, but they are still a bit short. Lowering the quill will still be necessary to do those tasks, but the distance is now quite small. And other jobs will now be possible without lowering the quill. Machine rigidity, and therefore precision, should be improved.
Just be aware that the upper stop isn’t where you may remember it to be, and that there are more collision possibilities as a result. Attention to your table movements is even more important near the top of the table range.