Just managed to resolve the curve issue in the previous posting and machine doing perspex cutting jobs as usual. with perfect curves.
was on for maybe half an housr at %30 power and noticed power diminish rapidly to zero over the space of 2 minutes or so,
about to stop the job when bang, rattle of broken glass being pumped through laser tube, and water p*ssing onto floor.
so run to switch off mains and get rags to deal with water amid much swearing.
doesnt appear to have been any cooling problem - water about 20 deg C pumping as normal. the inner cooling coil cracked and the gas fill ,nipple' of the glass outer tube blown off.
any ideas what could have caused this ?
fortunately i have spare tube with which to complete a couple of jobs but the pain of aligning it is something i could have done without this week of all weeks!
cheers KPB