lens longevity

[jud dinsmore]

60w hurricane laser. we mostly engrave in wood, but occasionally cut 1/4" plywood panels. we're using it (average) less than five hours a week.

i replaced my 2" lens with an inexpensive one from amazon a few months ago. we've been cutting a few templates from 1/4" ply and the cut depth has been inconsistent. it appears the lens is on its way out.

how often should i be cleaning the lens?

are better lens worth the money?

what can i do to increase the usage between replacing the lens?

[Kev Williams]

If the lens isn't covered with black char, which happens, and is only marginally scratched up, it's likely not the problem with the inconsistent cutting.
I say this because--
368563
THIS lens, with the cracks and dual halos left from cleaning black char (which caused the cracks), cuts and engraves exactly the same as any of my other lenses.

But $18 lenses are available on Ebay, no they're not very durable, they tend to scratch fairly easily, but for the price, they're a cheap consumable, and a new one will tell you if the old one was the culprit.

You may have a smudge or some other guck on a mirror or beam alignment issue-

How's your cooling water temp? As it's temp goes up, power density goes down...

[jud dinsmore]

kev,

my water chiller stays at around 19c. we make sure we turn it on 10-15 minutes before we run the laser.

i ordered two new lenses this morning and they should be here on wednesday. last time i switched out the lens (a few months ago), the difference was pretty night and day. i just figured i was operating from the old/original lens so i was surprised that this one seems bad already. maybe my expectations are wrong?

[Mike Null]

In 20 years I've never had to replace a lens. My current one is 11 years old. Keep the lens clean and use your air assist when cutting.

I have always declined jobs where cutting 1/4" plywood was necessary. I had issues with that as well but I was working with a 25 or 45 watt machine.

[Doug Fisher]

>>cutting a few templates from 1/4" ply and the cut depth has been inconsistent. <<

It might be your lens but it might just be the plywood itself. If you are using the cheap imported plywood at the big box hardware store, the plywood can be highly variable in how much glue is used and the type of glue used. Some of that stuff is really hard for a laser to cut through while other pieces can cut just fine. Throw in the fact that they often stock plywood from multiple vendors and you can have real issues with consistency.

[Robert Bonenfant]

Our lens average about 2 - 6 months but we are cutting atleast 40 hours a week per machine. You should be cleaning your lens each day before you start cutting, We clean ours each morning with some distilled water and cotton swabs and we are good to go all day. Cutting plywood is very messy and requires machine cleaning more often than most other materials. Try a few name brand companies and find a good lens that works for you, we have found after trying some of the ebay and amazon lens and mirrors there is a huge lack of quality and they dont last long at all. Make sure you keep your mirrors clean as well, this is just as important as your lens.

Trying cleaning your lens and a quick mirror clean each day you use your machine and it should show great results right away.

[jud dinsmore]

thanks for the notes. we've only cleaned the lens one time (yesterday) and have never cleaned the mirrors. i'll give that a shot.

our 1/4" ply is imported. is there something else that would work better for template material (and considering costs, i'm sure there is a better medium)? we're using 1/4" ply, cut on the laser, as a template to make a 3/4" mdf template. we then take the 3/4" mdf template and use it to make cuts in the wood.

[Robert Bonenfant]

The best wood we have found so fair for cutting and affordability is Russian Baltic Birch. We go through about 15 skids a month of 1/8,1/4 and 1/2" and it always cuts well. It has a solid birch core so its strong and cuts great each sheet. We use it for our laser cut parts and we make tons of cabinet components - Since it has a solid core there no voids and we dont often see hard spots. Most plywood wholesalers have it in stock or can order it.

[Mike Null]

I clean my lens 3 or 4 times a day if I'm cutting wood or a lot of plastic. Mirrors less often. I also do a lot of Cermark which is a dirty material.

I never use water. Always lens cleaner or in a pinch acetone.

[Robert Bonenfant]

Mike why so often ???

With positive air flow the lens shouldn't be getting dirty that fast - We have two shifts on our lasers today (16 hours) and will only be cleaning them twice on a bad day.

Just curious , Im sure trotec lens are alot more expensive than my $30 lens so I might have answered my own question :-)

[Doug Fisher]

I use quality eyeglass cleaner which is good at cleaning light gunk off. Additionally, I have a dedicated micro fiber cloth for cleaning the lens because many lenses are coated with stuff that you don't want to get on other stuff. The cloths are cheap at the glasses counter at Walmart and they don't damage the surface/coating of the lens. A good wetting, application of mild dish soap and thorough rinsing under the tap will keep the cloth clean.

[Mike Null]

Robert
Compare my replacement frequency with yours. Granted, I don't cut much wood but I do cut a good bit of plastic and do a lot of raster engraving.

My mirrors rarely accumulate any grime but I do not use air assist on raster engraving as I find no apparent benefit. As Kev says in the next post, Cermark can make a mess of a lens in a hurry and as a matter of habit I clean the lens after a couple of hours of using Cermark.

[Kev Williams]

Mike why so often ???

With positive air flow the lens shouldn't be getting dirty that fast
That's the trick, that positive airflow...

I don't cut wood, but I engrave and cut a lot of engraving acrylic.. that said--
My LS900 lens stays clean for weeks no matter what I engrave or cut. My mirrors hardly ever get dirty. GREAT airflow, NO smoke drifts upward.
My GCC lens and mirrors stay clean for a few minutes no matter what I engrave. It LOOKS like it has good air flow, but doesn't, and I'm working on that :) -- After engraving a square foot of anything on Romark, there's a haze buildup on the mirrors that highlight the red LED- a quick swipe with a dry Q-tip and the LED becomes almost invisible. And that's the mirrors, the lens gets worse, faster. I clean its lens and mirrors before any job, and especially Cermark, as a little haze can be the difference between being done or having to run a second pass.

[Joe Pelonio]

When I was running 8 hours a day I would clean twice a day, now only after a big cutting job. I have replaced all mirrors once, lenses twice, and that’s in 13 years. I still have and use the cleaner liquid provided by Epilog when I bought my machine, and Kodak lens cleaning tissues.

[Robert Bonenfant]

Mike that makes sense and im sure trotec lens are alot higher quality than the junk ones we use. We could run them longer but for $30 a lens replacing them after a few months make sense if we see any type of imperfection. For the cost of the trotec lens I would probably clean them more often as well.

[Mike Null]

Robert
It's more typical for me to clean twice a day if I'm doing a lot of cutting or engraving. When I did an order for several thousand pieces of wood I cleaned every hour or so.

I can't speak to the quality of the lenses you're buying but this company is the supplier to Trotec. http://www.iiviinfrared.com/CO2-Laser-Optics/mirrors.html

[Brian Lamb]

So what do the lenses cost from iivi? And what type of lens is it that we use in a CO2 laser? They don't list lenses per application on their website, i.e. Trotec, ULS, etc. so it's rather confusing... I suppose a phone call would get the answers I need, just haven't done it yet. I'd like to get a back up 2" lens and a 3 or 4" focal length one for some rotary applications.

[Scott Shepherd]

So what do the lenses cost from iivi? And what type of lens is it that we use in a CO2 laser? They don't list lenses per application on their website, i.e. Trotec, ULS, etc. so it's rather confusing... I suppose a phone call would get the answers I need, just haven't done it yet. I'd like to get a back up 2" lens and a 3 or 4" focal length one for some rotary applications.

Probably close to $150. You need to measure the diameter and thickness of your existing lens. Call them and they'll be able to work with that and determine the right lens.

I'm with Mike. We have 4 or 5 lenses of different focal lengths and they look perfect. I know one of them is 7-8 years old and not a spec or pit on it. I think we ruined one lens once, by having air assist off and the nose cone on. Other than that, depending on what we are doing, we'll clean them a couple times a day to a couple times a month. Having said that, we check them every day. No dirt, no need to clean it, dirt, clean it. It's worked this long, so we'll keep doing that.

I guess our ULS is 10 years old now and it has the original lens and mirrors. Not a spot on the lens.

[Barb Macdonald]

Fascinating thread, thank you all.
Dumb person, aka me, forgot to clean lens (mirrors and encoder strips yes, lens, no) for a very long time. Finally noticed it, cleaned it, and I have two half-moon black rings (tiny) off centre of the lens. Vectoring improved as soon as I cleaned it, duh... Will I harm the beam if I don't replace the lens? Seems to be working fine. epilog legend ext, mature model from 2006. Airflow has been the bane of my existence, but it's the best we can do.
Apologies for the stupidity of the question...

[Jacob John]

Fascinating thread, thank you all.
Dumb person, aka me, forgot to clean lens (mirrors and encoder strips yes, lens, no) for a very long time. Finally noticed it, cleaned it, and I have two half-moon black rings (tiny) off centre of the lens. Vectoring improved as soon as I cleaned it, duh... Will I harm the beam if I don't replace the lens? Seems to be working fine. epilog legend ext, mature model from 2006. Airflow has been the bane of my existence, but it's the best we can do.
Apologies for the stupidity of the question...

Post a few pics if you can.

[Rodne Gold]

The cheap lenses do not engrave etc as well as the OEM expensive ones..ours in a VERY harsh environment last about 6 months , but at the price , they are considered consumables .. we have 9 lasers running almost continually , 8 of them use lenses .. so we keep quite a few in stock
OEM lenses last a lot longer.. 2 years sometimes , but despite training my operators re cleaning , its pretty rough and ready (spit and the corner of a shirt) , so we hae moved over to the cheapy lenses for general work

[Barb Macdonald]

Post a few pics if you can.

A few, as in one? :)370939
Abigail cut amazing yesterday. Thank you for asking, sorry it took so long.

[Nick Hale]

If I am etching mostly wood my lens stays mostly clean, due to the air assist. I mostly etch powdercoat which I do not use air assist. So it will put a film on the lens and then the laser will burn the lens. I go through a lens about every two weeks. I use the cheap $30 amazon 20mm lens on my 100w CO2. I am not very good with staying on top of keeping the lens clean either.

[Jerome Stanek]

If I am etching mostly wood my lens stays mostly clean, due to the air assist. I mostly etch powdercoat which I do not use air assist. So it will put a film on the lens and then the laser will burn the lens. I go through a lens about every two weeks. I use the cheap $30 amazon 20mm lens on my 100w CO2. I am not very good with staying on top of keeping the lens clean either.

Could you aim some air across the path of the beam

[John Lifer]

Why with cutting powder coating on stainless steel would you NOT use air assist? It shouldn't really stick back to surface. Nothing like engraving acrylic materials.
I would expect even with no air you are having to clean somewhat.

[Jerome Stanek]

When I said to blow across the beam I didn't mean to blow down but sideways to move the smoke away from the lens

[Mike Null]

I don't use air assist on powder coat either. I do one pass and clean with a magic eraser. Air assist is of no benefit in this operation.

[Jerome Stanek]

I don't use air assist on powder coat either. I do one pass and clean with a magic eraser. Air assist is of no benefit in this operation.

We are not talking air assist just how to keep the lens clean using air perpendicular to the cut

[Mike Null]

Jerome
The exhaust on my machine is quite efficient at removing the smoke above and below the work. I do a considerable amount of laminated plastic which is fairly dirty with residue. The exhaust handles it pretty well. Keep in mind, my lens is 11 years old so something is working.

[Craig Matheny]

Trying cleaning your lens and a quick mirror clean each day you use your machine and it should show great results right away.
Robert we do the same thing but found cleaning them at the end of the day gives all night for any moisture to evap. Just a thought

[Chase Mueller]

In 20 years I've never had to replace a lens. My current one is 11 years old. Keep the lens clean and use your air assist when cutting.

I have always declined jobs where cutting 1/4" plywood was necessary. I had issues with that as well but I was working with a 25 or 45 watt machine.

I'm sorry... Did you say 20 YEARS??? That's impressive. Albeit, I'm no expert or anything, but 20 years.. that's amazing.

[Mike Null]

That is correct and on my last machine which was 11 years old, the new owner is still using the same lens. (and the original mirrors)

[Joseph Shawa]

Depends on:

Power. If you are running at 180 W 100% Which I have done trying to depth engrave then the lens can get hot and crack....probably wasn't enough air.
Dirt on the lens. Dirt absorbs heat and lens gets hot. Also can bake on and then the coating comes off when you clean if it isn't off already.
When you aren't centered down the middle of the cone tip then that can get pretty hot. I've always wondered if temp affects the lens. Usually have to use higher power anyway if you aren't centered .

I get my lenses from laserwd.com. Consistent high quality and not expensive.

[Kev Williams]

My old 1997 ULS that my BIL owns now is still on its original lens. The coating is actually looks to be in sad shape, but it still puts down a crisp readable 1mm. tall letter...

My 14 year old LS900 lens is original, and Gary will have to let me know if the lens in my 12-13 year old GCC is the original, although I suspect it is-- not sure who made that particular lens, but even after 3 years of my brutal cleaning the thing has nary even the faintest of scratches. My $20 Ebay lenses have more scratches fresh out of the box!

[Joseph Shawa]

But what's the power of the laser?

[Gary Hair]

Gary will have to let me know if the lens in my 12-13 year old GCC is the original, although I suspect it is--

yep, the original lens.

[Ian Stewart-Koster]

Plywood... interior grade glue lasers dead easily.
Exterior grade glues (most) can be harder to laser through than the wood itself, and vary in thickness and density.

[Meagan Britz]

What kind of mirrors please? I'm having horrible mirror issues, however I live in Fiji with high heat and moisture and I tend to buy cheap mirrors. I'm looking to find advice on long lasting mirrors and am happy to pay the price!