when I did this could not find the R40 bulb. Instead use a Sylvania 200Watt bulb
#S488. I have it inside a small aluminum cone and have the lamp attached to a pulley on the ceiling for convenience if I need to raise or lower the bulb. So far I have it set at 37 inches and it works perfectly. Times range from about 25-50 seconds for grade #2. Hope this helps....(also gives a great suntan)
Best, Peter