Here is my $0.02 about the water pump. After only a few hours of use the impeller jammed and starved the tube of cooling water. I was most fortunate that the tube did not sustain any damage (at least that I can tell). It seems imperative that a good pump (even a Harbor Freight pump is better) and a water flow indicator of some sort is required. I think I will set up a cut-out circuit to shut down the machine as well as an audible alarm just to make it more dramatic. Do you think flashing lights and a klaxon would be too… over the top?
A warning lamp and or an audible alarm would be useful. More important is the interlock to inhibit the laser when cooling is not present. A useful addition would be if the alarm latched on, this would draw attention to an intermittent flow which could otherwise be missed. Hth David.