Vytek L-star series banding and lasering problems

[victor belfour]

Hello everyone. This is my 1st post here. Hope someone can help me

I work in an industry where we do laser etchings onto polished flat rock (mainly granite and marble, mostly headstones). We use a vytek laser, one of the L-star or LS series lasers (our model# is LS 4896) , it is a 35 watt machine.

About a week ago our laser started producing less than stellar results, banding started showing up in the white area's of larger etchings. 1st it was vertical. We cleaned the laser lens but now horizontal banding was showing up. Additionally now. After several laser lens cleanings the laser is not shooting well at all. Etchings come out "dark". Whites are not white and at the end of the image being burned, the laser looks like its fading the whole image away; as if its losing power. We've tried several old jobs that we have already lasered with good results but now are coming out faded. We are currently undergoing a thorough cleaning of the machine but are not sure this will solve the problem.

Additionally, after cleaning the laser lens we have noticed the lens has a thin coating that is peeling away on the surface. Vytek has never mentioned that their lenses deteriorate overtime and we are wondering if anyone else has encountered this problem. Please see attached photo of our lens.

http://i99.photobucket.com/albums/l2...35mm_dslr2.jpg

If anyone has any suggestions or has encountered similar situation i'd like to know how to resolve it. This is holding up our production in a big way.

Thanks

[Scott Shepherd]

Don't know anything about Vytek, but lens do get damaged and wear over time. I would guess that lasering stone products would do nothing but accelerate that process.

[James Stokes]

That lens could very well be causing the problem. Change it and see how the laser does. If that does not fix the problem you may have to have a recharge on your tube.

[victor belfour]

Don't know anything about Vytek, but lens do get damaged and wear over time. I would guess that lasering stone products would do nothing but accelerate that process.

Hey thanks for your quick reply!

I'm just unclear how lasering stone would deteriorate the lens that much quicker? We have the compressor running at all times when using the laser and I'm assuming that the debris from the etching is being blown away. Is there the possibility that some of that has come up into the lens area? The degradation looks more like peeling than abrasion.

[victor belfour]

That lens could very well be causing the problem. Change it and see how the laser does. If that does not fix the problem you may have to have a recharge on your tube.

Thanks for your input!

I've read mention of "tubes" in several threads here but i'm not sure what exactly this means. Is this the light source of the laser much like the light bulb in a video projector? I know those dim and burn out over time due to their high intensity and constant on and off use. Is the laser unit prone to this type of dimming and failure over time? Vytek had never mentioned this type of maintenance and had said this machine should be basically "maintenance free". Our model was manufactured in January 2007 so its just a year and 1/2 old.

[Neal Schlee]

How long is the Vytek warranty? Longer than a year I'd hope. Banding can also be caused by worn lense carriage bearings.

Neal

[Scott Shepherd]

I'd call Vytek's tech support and send them the photo of the lens and see what they say. Might be a defective lens, or might be what the consider normal wear.

Air assist certainly helps, but nothing is perfect and when you're chipping away tiny bits of stone and blowing air into those particles, it could cause some minor issues. Is that what's happened? I have no idea and I wouldn't speculate on the cause, I'm just raising this issue that any time you laser something abrasive, the wear possibility goes up (along with the maintenance to keep it clean).

[Dan Hintz]

I'm assuming this is an RF-powered laser. If it's not the lens, the RF section of the power supply could be going bad, or the tube could be in need of a recharge. It's not common for an RF-based tube to need a charge so quickly, but they do need recharging from time to time (20-40k hours should be a good average benchmark, though this is strictly an average and outliers do exist). It doesn't take much of an out-of-spec component in the RF section to trash the supply... a bad cap can lead to some nasty oscillations that can kill the FETs in a hurry.

[Jack Harper]

I have the big brother to yours. There are a couple of mirrors in the end of the head that need occasional cleaning and alignment. Get you book out and read up on aligning the beam. With all this said, I am in agreement that the problem is probably the lens. Vytek warned us not to clean too often and when doing so, clean very very gently to avoid wearing off the coating.

[Mike Ireland]

Regarding the banding: vertical banding usually has a mechanical cause such as worn belts, bearings, etc. Horizontal banding is usually caused by the laser tube. It could be failing, which would be indicated by the faded engraving caused by less power. Along with the lens, you should also check the output power of the laser tube.

[victor belfour]

How long is the Vytek warranty? Longer than a year I'd hope. Banding can also be caused by worn lense carriage bearings.

Neal

vytek only warranties its products for one year. considering the costs i would've thought it would be longer. Are its competitors the same?

[victor belfour]

I'd call Vytek's tech support and send them the photo of the lens and see what they say. Might be a defective lens, or might be what the consider normal wear.

yes. we've sent vytek support the photos. They have said that lens wear does happen.

Air assist certainly helps, but nothing is perfect and when you're chipping away tiny bits of stone and blowing air into those particles, it could cause some minor issues. Is that what's happened? I have no idea and I wouldn't speculate on the cause, I'm just raising this issue that any time you laser something abrasive, the wear possibility goes up (along with the maintenance to keep it clean).

yes we're thinking that too. after an engraving there is lots of particles left on the material and engraver bed that basically amounts to dust but courser. We also do a test run of our designs on glass before lasering on the material itself so i'm sure particles from the engraving materials are accumulating everywhere around the engraver. whether this is shooting up the lens that emits the laser is speculative. Our lens doesn't look scratched or sanded but more looks like a peeling of somekind is going on. but you might be right. We're not sure.

[victor belfour]

I'm assuming this is an RF-powered laser. If it's not the lens, the RF section of the power supply could be going bad, or the tube could be in need of a recharge. It's not common for an RF-based tube to need a charge so quickly, but they do need recharging from time to time (20-40k hours should be a good average benchmark, though this is strictly an average and outliers do exist). It doesn't take much of an out-of-spec component in the RF section to trash the supply... a bad cap can lead to some nasty oscillations that can kill the FETs in a hurry.

By RF i'm assuming you're meaning Radio Frequency? I'm not sure hot to tell what our power supply is, it plugs into 220volts here i'm assuming, my boss might be able to tell me more about that. It truly does feel like the laser runs out of "steam" so to speak, as the last couple engraves we have done started out fine but then white intensity starts dropping off and gets dimmer and dimmer towards the end. Who would we have to contact in order to recharge the laser? Can you elaborate: What is a "bad cap"? FETs? I'm not sure what those are.

Thanks for your input!

[victor belfour]

I have the big brother to yours. There are a couple of mirrors in the end of the head that need occasional cleaning and alignment. Get you book out and read up on aligning the beam. With all this said, I am in agreement that the problem is probably the lens. Vytek warned us not to clean too often and when doing so, clean very very gently to avoid wearing off the coating.

How long have you had your vytek laser for now? Are you operating it in a very "sterile" dust free environment? Yes, they warned us about the delicacy of the lens. It has not been cleaned on regular routine basis. I dont think it was our cleaning that wore off the coating, and vytek didn't accuse us of that either after they examined the photos i sent them of the lens.

[victor belfour]

Regarding the banding: vertical banding usually has a mechanical cause such as worn belts, bearings, etc. Horizontal banding is usually caused by the laser tube. It could be failing, which would be indicated by the faded engraving caused by less power. Along with the lens, you should also check the output power of the laser tube.

thanks for the suggestions. How does one test the ouput power of the laser tube? does it involve special equipment and a technician? Where can we find such a person. We're up in Canada.

As a test for myself. I created a solid white vertical line about 1" wide and 20" long in photoshop and put a fade to black on its edge so the image goes from solid white fading to black. I processed this through photograv and then sent it to the laser to shoot onto a piece of scrap glass spray painted with some flat black paint to show the etching better. The laser starts shooting the vertical line from black to solid white. As the laser moves down and continues to etch the line downwards though, you can see fluctuations in the white portion of the etching as if the laser was losing intensity. Please see photo. The white portion should be uniform in intensity.

I also flipped the design to the horizontal plane and ran it, there wasn't nearly as much fluctuation in the white as there was in the vertical burn previously and seemed to exhibit no banding, see photo2; but these were both small tests.

Has anyone seen this type of problem?