Lighting

Accidentally deleted first post.

It was:

Is there a problem using flourescent light above a machine?

Edited By David Clark 1 on 22/09/2012 19:13:14

There's a 5ft flourescent light above my lathe and I don't have any problems.

Roy

There is no problem with fluorescent lamps only hearsay comment. I have an inverter fed lathe and there is NO strobing at all from RPM up to 2400RPM, you cannot make the chuck appear stopped, so no problem.

Hi again ME forum, Southern Sailor here. I posted the same query on Model Boat Mayhem forum and received very helpful and informative replies, one of which was:

"Actually it is a problem & can cause very dangerous situations around any rotating machinery. You should always in addition to fluorescent light also have an incandescent light as well where you have rotating machinery. As you will see most machines have their own incandescent light fitted, especially grinders & lathes. Fluorescent lighting causes a strobe effect & will make under certain circumstances spinning machinery to actually look stationary, very dangerous. As an aside in hockey rinks they nearly always have an incandescent light above the the net to eliminate the strobe effect on the puck so that it does not create an optical illusion on the goalkeeper. Mick B."

I have reproduced that reply here to pass on some good advice. I will, as a result of the mayhem suggestions use electronic balasts for my workshop.

Sail on sailor

Brian

As above - never seen this often mentioned phenomenon.

Even if the chuck did appear stationary, the whine of the motor and the fan on the inverter soon gives the game away that the lathe is under power...

I do know that there is a vast variety of tubes and particularly colours that will make a huge difference to your viewing experience.

I remember seeing a lathe chuck aparently run backwards slowly when in actual fact it was going forwards very quickly, but this was at high peak college in Buxton, 27 years ago...It was caused by the lighting for sure. I find it much better to use lots of low wattage energy bulbs in my workshop.

I believe there was more risk of strobing effects with older flourescent fittings - with more modern fittings and the even newer high frequency systems the strobe effect that makes rotating chucks appear stationary are more or less eliminated.

I posted a nice explanatory post but David deleted it.

Hi John

Post it again.

I deleted a couple of p[osts by accident.

regards david

Hi John

Post it again.

I deleted a couple of posts by accident.

regards david

Edited By David Clark 1 on 23/09/2012 11:20:04

Hi David,

This is an extract from Wikipedia which explains the problem and solution:

"........Even among persons not sensitive to light flicker, a stroboscopic effect can be noticed, where something spinning at just the right speed may appear stationary if illuminated solely by a single fluorescent lamp. This effect is eliminated by paired lamps operating on a lead-lag ballast. Unlike a true strobe lamp, the light level drops in appreciable time and so substantial "blurring" of the moving part would be evident."

Lathes at least in schools used to be supplied with a low voltage incandescent lamp which I was always led to believe were to overcome the possible stroboscopic problem but now most workshops are lit with dual lamps as described above. I use fluorescent tubes for general lighting but supplement each machine with localised Halogen lamps and my bench with a daylight simulated compact fluorescent lamp.

Terry

Edited By Terryd on 23/09/2012 11:49:30

Right try again.

Last place I worked at we had to grind very small drills and cutters by hand on freehand wheels, no rests.

The help us we had strobe lights fitted to the grinders that could 'stop' the wheel so you had a better chance of seeing what you were doing. They worked and worked well.

Later on as the grinding shop was dragged kicking and screaming into the 19th century some of these strobe units were discontinued and I 'won' one.

At a later date I had some deep bearing housing to bore down inside some skeletal pump housings so I set the strobe up to shine on the housings to 'stop' the housings so i could see thru the gaps into the bearing bore.

Because I had the strobe, which was quite bright, about 18" away do to the shape of the housings it didn't work. plenty of flicker but I couldn't stop the housing at any setting even though I knew the revs to a tight margin.

So after the job was done i tried again with the strobe set up 6' feet away, about the same distance as the ceiling lights. Again plenty of flicker, enough to be annoying but couldn't stop the chuck.

I can see why in theory it should work but given the average light is say 60W and a fair distance away I can't see it happening in practise. I certainly couldn't' get it to work with a strobe that had a massive adjustment range on it and not reliant of a set 50 Hz

For a strobe effect with flourescent tubes the light flashes have to be at the same frequency, inverse of speed, as the chuck or a direct multiple. In theory this could happen but in practice it is unlikely. I light my workshop with low Wattage flourscent tubes for general lighting and low Voltage halogen lights over machinery and have never seen a strobe effect.

Just to worry you, I recall an article written by someone who had looked at the strobe effect of incandescent lights. Surprisingly some effect was present with most lights and it could be significant. I think it was in The Model Engineer about ten years ago.