"Tim Lamb" wrote in message
news
In message , Bill Wright
writes
On 31/12/2019 16:52, Tim Lamb wrote:

I once discovered that British Rail carriage lamps fitted my Boxford
centre lathe work light!

On a school trip to London I stole all the bulbs out of the train
lavatories*. They fitted the light sockets in my mate's house where we
tried them but were a lower voltage and went off like flashbulbs.

*This was when I was a pupil, not a teacher.

:-)

A while back now so I have forgotten the detail. The lathe was originally
3 phase and I had fitted a 3/4hp single phase motor for domestic use. The
work light was transformer operated and possibly 24V o/p.

First rule of work lights for lathes and other tools that move: always use a
*tungsten* bulb or else a light that is *permanently on* (DC-powered
tungsten or LED with current-limiting rather than fast pulsing with
controllable mark:space ratio).

The reason for this is that you want to avoid the situation where the
rotating tool/work appears to be stationary or very slowly rotating because
the stroboscopic effect of the pulsed fluorescent or LED light at certain
work speeds and pulsing rates. OK, so an AC-powered tungsten will flicker on
and off like a fluoescent will, but the thermal inertia of the filament will
mean that the stroboscopic effect will be much less apparent, so even if
there is a stationary image of the work, there will also be a clearly
blurred version.

I remember my grandpa (who made model steam locomotives on his lathe)
telling me this: his workshop was illuminated by 5-foot fluorescents but he
had a 60W tungsten bulb as his work light.