Thread: Auto darkening welding helmets

I'll echo the last post - be wary of cheap ones. They might be alright for occasional use - that is once or twice a day!! Not likely - but quite a few have been slow in their response so that the operator gets a little flash every time. Yours eyes are worth more than a few dollars.
Cheers

I have to agree, forget the el-cheapo's. I paid a bit over $150 for mine,(Toolex) it activates quickly, has adjustable shade and adjustable sensitivity if you are welding with low amps (the book says it will work with arcs of as little as 5 amps). The lens is a nice green shade when inactive and you can see through it OK under normal lighting. I love it.
Dennis.

'scuse my ignorance, but I am curious. Back when I was doing a welding engineering course, these helmets were very expensive (not much change from a grand), and so I never looked into them (sic). My question is this: Given the speed of light, how in the world do any of these helmets darken quickly enough for the operator not to get a flash in the eyes? Or do you deliberately blink just as the arc is struck to avoid the momentary burst?

Aaah, well, this is where it gets interesting. The light produced by the arc causes the photovoltaic cells to produce electricity. This electricity is used to activate a liquid crystal display panel which goes partially opaque, thus blocking the light from hurting your eyes.
The reaction time for all this activity depends on the quality of the electronics. Cheap electronics = slow reaction times, more expensive electronics = faster reaction times. The expensive bit is still the LCD panel.The PV cells are fairly cheap but the larger they are the better things seem to work.
Ain't technology wonnerfull?
Dennis.

Ok, but the arc flash, being light is travelling at, well, the speed of light, and hitting your eyeballs at the same time as the photoelectric panel. There is time then between the panel being struck by photons, the released electrons travelling along to the LCD panel, which then takes an amount of time for the crystals to align and darken. All the time the arc light is in the eyes. I'm quite happy that they work, that good ones operate quickly, that they are the bees knees when you are welding etc, but is it so fast that the brain doesn't have time to register the flash? Or do you notice the flash, but it is too brief to cause discomfort, and the next morning's 'sand in the eyes'? Or have I just answered my own questions??

Originally Posted by stuart_lees

'scuse my ignorance, but I am curious. Back when I was doing a welding engineering course, these helmets were very expensive (not much change from a grand), and so I never looked into them (sic). My question is this: Given the speed of light, how in the world do any of these helmets darken quickly enough for the operator not to get a flash in the eyes? Or do you deliberately blink just as the arc is struck to avoid the momentary burst?

I have used one of the helmets once for three days of metal fab work. (built new shed for work.) After long periods of continous use my eyes did get sore the the milleecond of flash that I got everytime. Personally I agree with journeyman Mick's suggestion of flipping your helmet. Its the only way to garantee no flash.

FWIW, my tafe teacher told me that you should wear a pair of UV protected safety glasses under your welding helmet. It stop the UV light from the welding flash from hitting your eyes if you don't get your helmet down in time. Apparently the UV part of the light does the worst damage.

I ran a few welds on the Syd-Melb gas pipeline, like a coupla k's of weld, and I never saw one auto darkening helmet amongst the gun welders. This is a good hint.

Cheers

Well, Stewart, I think that there must be an explanation for all of this.
I actually took notice of what was happening while I was welding today and what I think happens is that when you strike an arc there is an initial spark which is sort-of yellow in colour and this then becomes the blue coloured arc which does all the fusion of the metals. What seemed to happen was that I could see the spark as an ever so brief yellow flicker, then the lens darkened and then I could see the arc form and stabilise. With a hand as unsteady as mine that stable arc can be pretty brief at times but sometimes I get lucky!
Once again, my feeling is that the sensitivity of the solar panels to the amount of light produced by the initial spark, coupled with the fast switching speed of the LCD panel are the secret to success.
I think.
But I could be wrong.
Dennis.

Cheers Dennis- nice explanation. Given that UV is the real damaging light emitted from welding, and that the initial strike starts yellow, warming to blue and therefore UV, then that must be how the helmet gets away with it. It must react bloody quickly to the initiation of the arc, but it does so before too much UV is emitted.

Interesting to hear what Squizzy had to say too.

Originally Posted by vsquizz

I ran a few welds on the Syd-Melb gas pipeline, like a coupla k's of weld, and I never saw one auto darkening helmet amongst the gun welders. This is a good hint.

Cheers

Yeh, but what about the average welders?

Stuart, different types of welding yeild different light loads. My favourite lens is a No 13 gold film but doing some mild steel mig today I couldn't see diddly squat. (I'll get a No 12 tomorrow - or it could just be the years catching up )) I use the No 13 for flux cored low hydrogen mig, plasma cutting and tig root runs where I learned (Like Glock/Trevor) that some auto lenses cannot handle the instantaneous arc burst.

What I'm saying is that while I don't see heavy duty weldors using them I'm sure a quality unit doing some arc/stick or gas shielded mild steel welding for the home handyman should be OK. I'd look for some AS, Euro or Yank compliance spec on the helmet.

I do actually own an auto helmet (somewhere) but I like seeing.....
Cheers

Being only an average welder and only ever having used GP rods with a normal stick welder I would have to agree with Squizzy about the instant arc thing. A cheaper helmet may be too slow to react.
Odly enough though I was introduced to auto helmets by a bloke that was, at that time, a welder and fabricator as well as the owner of a welding and engineering supply business. What Ray didn't know about welding wasn't much. He used MIG for just about evrything and said that the helmet he was using was "the bees knees". The only problem was that the helmet was worth about $400 at that time. Out of my price range.
The auto helmet has saved me from quite a few flashes since I bought it though, and from that point I am really happy with it.
Pitty Ray sold the business, the new bloke knows SFA about welding.
Dennis.

Originally Posted by vsquizz

I ran a few welds on the Syd-Melb gas pipeline, like a coupla k's of weld, and I never saw one auto darkening helmet amongst the gun welders. This is a good hint.

Cheers

Never got my pressure pipe ticket, only got as far as the pressure plate.
Couldnt stand any more night school.

Al

Originally Posted by ozwinner

Never got my pressure pipe ticket, only got as far as the pressure plate.
Couldnt stand any more night school.

Al

Its a mugs game anyway. Glad I'm out of it full time.
You can teach monkeys to weld you know Al