I built one in my machine shop class nothing that resembled a c-n-c in sight. Ahhh the good times. Just a dying bread of real operators due to the all mighty computers.
Mine take a few min to warm up, but once warm Just like daylight. When you turn the off you ahve to wait 10 minuts or so before you can turn them on again. Bulbs are a bit expensive, but well worth it if you ask me