i use an SPT 45w tube.....for last 3 years....never run full power....i've cut up to 1/4 inch cast acrylic, end currently use to engrave self adhesive 2 color labels for friends business....have replaced mirrors, lenses, belts, limit switches....but not tube yet......hours? 5 hours week for 45-50 weeks X 3 years....watch your temps...dont run full power...has been great......soon as i have to increase power to compensate.....i'll buy another