black spot on lens wont come off

[Harry Radaza]

hi all, new here.

have a universal versalaser VL300 50 watt machine. only 3 months old. recently was working on some locally available synthetic wood which apparently gave off a lot of residue. machine was on the job for 1 hour 15 minutes straight. After the project, we noticed a black spot on the lens. Tried cleaning it off several times with the lens clens that came with the machine but did not work. Could the residue build up have burned on to the lens due to the heat? Anyone had similar problems ?

been cleaning it now for 2 days and no signs of it coming off at all. it still engraves and cuts fine with no noticeable degradation in quality. however, I still would like to get this stuff off the lens. thanx for all your help.

[Kevin Huffman]

Hello Harry,
Welcome to the Creek.

I have seen this same thing with one of our M Series machines, we forgot to turn on the air assist while engraving some metal samples and the cermark went up and adhered to the lens. After that we couldn't get a decent engraving out of that lens to save our lives. We tried cleaning it for a couple of days and finally ended up replacing it. It was a $400 dollar mistake but a good learning tool. We keep the damaged lens in our demo room to show customers what type of affect not turning on the air assist blower can have on your optics of the machine.

The best way to stop this from happening is to not mess with that material any more. I know that is going to always be an option but it just creates to much debris. The next best thing you can do is get a higher CFM blower, it will pull more debris out of the engraving area before it has a chance to float around and get on the lens. Also make sure you have your air assist on at the maximium pressure allowed by your laser manufacturer. The air assist is designed to keep things like this from happening.

[Joe Pelonio]

Harry,

Kevin's the expert, but before giving up I have a product here made for removing vinyl lettering adhesive that does amazing things with removal of unwanted spots of various kinds, including the "shadowing" from the vector grid on unmasked acrylic. It's called "Rapid Remover" by RapidTac
and as far as I know available only at sign supply places. You'd dab it on with a q-tip and let it sit 1-2 minutes then rub with the q-tip. Maybe a local sign shop has some and will sell or give you a very small amount.
It's $30/gallon or $12/Qt where I get it wholesale.

www.rapidtac.com (http://www.rapidtac.com)

[Mike Mackenzie]

Harry first try cleaning the Len's with acetone. The spot was more than likely caused by having the air cone on and no air going through it. Be careful when using the air cone air must always be on and coming through the cone.

[Kevin Huffman]

Hey Guys/Gals,
I don't know about all that. Most of the time you only want to use what the manufacturer says to clean it with.

That is something you can try before you completely write it off but there is a protective coating that is usually on mirrors and lens that make it specifically for lasering. Once you take that coating off it isn't going to operate as the manufacturer intended it to work.

Just my thoughts on it.

[Joe Pelonio]

I don't know about acetone, I doubt that the coating would come off from the product I suggested, but anything's possible. I use it on painted surfaces and the paint doesn't come off. Still, this is a last resort so
if you ruin the mirror trying to clean it you would have had to buy one anyway if you didn't clean it. The fact that the laser still works means that the beam has not been focused on that spot yet, but when it does it will cause problems with your engraving, or like happened to a friend of mine, burn a hole in the mirror and cause additional damages to the machine.

[Harry Radaza]

thanx for the help guys...

1) I dont have an air assist just a standard exhaust blower which was ON at the time.
2) Lens still works well cutting and engraving so I'm afraid to put acetone or whatever to take it off. If it damages the lens that's one less lens I have in stock. Is acetone proven to be safe for lens?
3) Tho staying away from the material is the best thing to do, I wish I didn't have to. The material was really a big potential seller.

[Mike Mackenzie]

Harry,

We have used acetone to clean stubborn spots off of the Len's it won't hurt anything. Do not soak it in the acetone that will remove the glue holding it into the bracket..

It will not harm the Len's to try the acetone.

Also those systems are pre plumbed with air if you want to do that material you may want to look at adding the air cone and a compressor. You can use shop air as long as you regulate it and use a water trap and coalsing filter in line before the laser system.
This will most definatly help with keeping the len's clean and free of debris. It also helps a lot with cutting.

[Joe Pelonio]

Harry,

Also those systems are pre plumbed with air if you want to do that material you may want to look at adding the air cone and a compressor. You can use shop air as long as you regulate it and use a water trap and coalsing filter in line before the laser system.
This will most definatly help with keeping the len's clean and free of debris. It also helps a lot with cutting.
Without air assist I'd be surprised if you don't have a lot of flaming when cutting, especially acrylic when it's cutting near the edges. The air assist blows it out as well as blowing away the debris. I definitely agree with Mike on adding it.

[Lee DeRaud]

Without air assist I'd be surprised if you don't have a lot of flaming when cutting, especially acrylic when it's cutting near the edges. The air assist blows it out as well as blowing away the debris. I definitely agree with Mike on adding it.Flaming from acrylic?!? I've never seen that: at the correct power levels for my machine, it barely singes the masking.

[Kevin Huffman]

The acrylic we use flames up big time even if we have the right power/speed settings, we always have to run our air compressors.

[Harry Radaza]

tried acetone and still the black spot wont come off. any other ideas?

[George M. Perzel]

Hi Harry;
Can you feel the spot with your fingernail-is it a deposit or a pit?
Thanks
George

[Harry Radaza]

didn't try feeling it with my fingernails. Manual says to never touch lens. I wouldn't mind trying it if the lens was not usable, however, it still engraves and cuts just as good so I'm afraid to try anything that would make it a 2nd display for cracked lens (cracked my first one already). Is it safe to touch it with my fingernails?

[Bruce Volden]

Harry


I believe the touching the lens idea is so as not to leave any naturally occuring oils from your hands / fingers deposited (microscopically) on the lens. I had 2 of my machines serviced (Oct.) at the manufacturer and had a long and lengthy discussion about various laser concerns. I observed him just short of scouring, a lens on one of the machines. When I expressed my concerns he explained many things re: lens cleaning. Mainly always use a high grade lens cleaner-they were using a reagent grade acetone (much higher filtering, purity) and never touch lens with anything after cleaning--DUH!! Oh by the way the "scouring" had NO ill effect. I use a 10X loupe to check things. I draw a .003 hairline on the vertical, about 1/8" in length. Engrave @ 30 pwr, 40 spd, 300 DPI and observe how the dots align and apper in uniformity.


Bruce