Problem with Laser Not Engraving properly

[John W. Love]

Hey all,

We've been experiencing a problem with our Laser not engraving properly, and I thought maybe one of you would have an idea or suggestion as to what might be causing it and or how to fix it! We've been working on quite a few granite and marble pieces lately and it seems we are having a loss of power when we get to the bottom of a 12" x 12" tile. Our laser has a 18" x 25" bed, and we have been engraving either in the top corner (home position) or 2" from the top corner on each side. It seems that John read where one or more of you suggested the engraving would come out clearer if we made a jig (I think that's what he called it...it's a piece of mdf cut to make a new corner 2" away from the top and left side). Anyway, I made a rose on granite with text beneath it and the text did not engrave correctly...the heavier lines came out okay but the finer lines did not engrave at all. I was using a fancy script font (Edwardian Script) but still feel that the fine lines should have engraved without me having to run the laser over them repeatedly then finally get frustrated flip the picture 180 degrees, flip the tile 180 degrees so the text was now at the top edge and run it again. A similar problem occurred with Onur's chessboard we were trying to make for our son's birthday present. It engraved beautifully but one edge barely engraved at all. We tried to flip that around like I did with the text but that didn't work because somehow it was off just a little and messed up the piece. So, I'm wondering if anyone has any idea what would cause this? These are all 12" x 12" tiles and I would think we shouldn't lose that much power that close to the home position especially since we have a bed so much larger than that. I wonder if it could have anything to do with running the machine below recommended temperatures...it's been cool in the evenings when we usually laser anywhere between 40 and 55 degrees outside...and our laser says recommended temp is 70 degrees or above. However, our laser is inside the garage and we have the door closed so I'd guess it's at least a little warmer in the garage than outside. I also wonder if there's some maintenance that we need to do that might fix the problem. Any ideas or suggestions would be great!

Thanks

Alicia Love

[Scott Shepherd]

Hi Alicia, there could be several things going on. If you could post photos of the problem and tell us what machine you are using, it would help us a great deal.

One thing that comes to mind is you mention thin lines several times, I think. think vertical lines can be a real problem for some lasers, especially at higher speeds. The laser has to turn on and off to burn the line and it's on and off so quickly for those thin vertical lines, it can made for tough times. If you can tell us the make, model, the speed and power you are running at, or even include the file in corel format, I'm sure we can help you two work it out.

Also, the cold can certainly be an issue.

[Darren Null]

Beam alignment would be a first guess. The mirrors from your laser all have to be lined up to put the beam -insofar as is possible- through the middle of the lens. If just one is out, the beam can drift as the head moves. You can test by removing the lens, putting a bit of paper in there and giving it a quick zap with the head in different positions on your table. (say corners and middle). If the burnhole varies in position on your bits of paper; that's alignment.

Fix: Adjust the mirrors, again using bits of paper to find out where the beam is going.

Also, if you're losing power on the right hand side as well, it could be cack on your mirrors.

[John W. Love]

Ok, info on our machine. It's a Pinnacle M series 40 Watt machine. Our manual says to run both granite and marble at 100 speed 60 power unless you are doing photos on marble then it says 100 speed 10-15 power...we used the 100 speed 60 power on both of these. I will attach photos of the items...but keep in mind on the granite piece I flipped the item 180 degrees and also the picture/text so that I reran that part close to the home position. I will have John add pics when he gets home...I can't seem to figure out where they went when I tried to download them off my camera lol...

I will also try that test that you mentioned, Darren...maybe that will help!

Thanks all :)

Alicia Love

[John W. Love]

Ok here are the pics of the items...keep in mind I fixed the granite text by flipping the tile and the cdr 180 degrees but you can see the type of text I was doing. It was having problems on the lower right corner on the word "You" in the thinner parts of the text.

I'm going to try testing the beams today...but how do I "zap" the paper? Would I do this by making a new corel document with say a dot in the different locations I want to test? And assuming it's off I'm guessing that directions for adjusting the mirrors would be in my manual? Lol I have gotten a lot better with my skills on the laser but when it comes to doing anything to it besides cleaning the mirrors and the lens I'm still a newb...

Thanks,

Alicia Love

[Scott Shepherd]

Lower right problem in the "You" is probably too fast a speed for that thin line, in my opinion. Some machines allow you to tune them, which can correct that problem. Others don't. Not sure about yours. I'd try slowing it down to 80% and seeing it gets better.

The rest of the issues, looks like a focus or beam issue. Either the table isn't level or the mirrors are off.

Just my best guess, and that's what it is, a guess.

[Dan Hintz]

John/Alicia,

Love the pattern you're using around the edge of that board. My father is sending me a chess kit that he has had since he was in college... very detailed pieces, but I would like to create a new board for it on granite or marble. Your design has given me a few new sparks :)

[John W. Love]

Dan,

We can't take credit for the design on that chessboard...that is Onur's design. He sent us the file so we can make it for our son. We loved the design when we saw it on his thread about the art show he showed his stuff in :)

Alicia

[Bill Cunningham]

A lot of what they call laser grade marble is not marble at all.. from the look of the 'marblng' in the stone you are working with, I would guess that it's 'real' marble. In which case, I would try 100% power, and 30-40% speed.. Real marble takes a lot more power than some 'laser grade' stuff which I usually etch at 100% power, and 90-100% speed.. this combined with a alignment problem might be your problem.. Just a thought

[John W. Love]

Thanks for the help and advice. I am going to run the diagnostic tests on this tomorrow evening when I get home. I will let you know how it works out.
Thanks again,

~John and Alicia~

[John W. Love]

Well, we did a thorough cleaning of all the mirrors and that helped a lot. We also checked our beam alignment and it is slightly off. However, our manual gives very confusing directions as to how to fix that. It says "There are 5 screws on the back of the red beam mirror. The allen head screw is NOT to be touched at all." They are ALL allenhead screws so we left it alone. Our machine is 2 years old so I'm not really sure who we should call to get clarification lol. We purchased it from Sign Warehouse... I want to adjust the beam so that it is in alignment across the entire table. Funny thing is it looks to me like it's actually further off the closer you get to the home position.

Any suggestions?

Thanks

[Gary Hair]

Beam alignment isn't very difficult - the second time you do it... The first time is only difficult because you aren't sure exactly what you are doing. I have a Pinnacle/GCC Explorer ZX so it is similar to yours, but not exactly the same. There are documents and videos on the signwarehouse website that will explain the process in pretty good detail. Even though your machine is probably out of warranty, they should still help walk you through alignment if you run into trouble.

Alignment is something you need to know how to do, it will definitely help with the problems you are experiencing.

Gary

[John W. Love]

Thanks Gary, I went to the SW website tonite and did find a video on how to do the alignment. In the past it was done by the tech that came down here. All of the screws are allen heads, but from the video I was able to ascertain the two they kept emphasizing "DO NOT ADJUST" and adjusted the other three. Although the beam wasn't off by much in the beginning, I was able to tweak it just a bit to get it dead center at the farthest reach of the table. I am guessing that "lil bit" that it was off makes a big difference throughout the table.
The good news is I know how to do that now, so the next time shouldn't be so bad at all.

[Rodne Gold]

There is one key element to obtaining alignment with the mercury - and that is the alignemnt of the red dot pointer with the beam.
If you can use the red dot pointer as an accurate indicator of where the beam will hit , it makes life 100x easier to align the machine cos you can actually SEE what is happening in real time as you adjust instead of adjust/fire/adjust/fire etc.
There is only one way to check the red dot/beam alignment and that is to shoot the beam DIRECTLY from the tube over a long distance , say 10-15 ft and then align the red dot pointer to be EXACTLY dead centre on the burn mark , thereafter its realtively easy
A few tips , take the top cover off the machine when aligning, and make sure you are consistent with the torque or pressure you apply to the little thumb screw that holds the mirrors in place , cos if you apply more or less than usual , you WILL put out the alignment - tighten em up during and after alignment to the SAME pressure - always.
The mirror mounting bracket of the GCC are deplorable - silly thin stamped steel thing that can and do flex , If I were the laser designer , I would have machined these in solid hard grade aluminium and provided vernier type adjustment mechanisms
At one stage we considered doing this , but never got around to it.
A beam expander is actually useful for maintaining alignement as it widens the beam and makes sure diffraction when hitting the final lens is minimised, IE
---!------
will bend more than
--!!!!!----
If that makes sense at all.

[Frank Corker]

Is it possible that there is a difference in height of the beam at the top left side of the bed and the bottom right? I would measure the distance from bed up to the beam carrier, then move it to the bottom right and measure it again. If the two are different you might be able to adjust that.

When I first got my Epilog I somehow managed to get mine messed up. On autofocus the bed rises up until it hits the plunger, that's when the machine stops. My plunger missed the workpiece and went through the cutting table, then the bed was stuck at the top and wouldn't come down. It had to be manually wound back down. I noticed similar problems to what you are having. When I measured I found that I was actually much lower on the right than on the left. A few tweeks and it was right as rain.

[Steve Clarkson]

My plunger missed the workpiece and went through the cutting table, then the bed was stuck at the top and wouldn't come down. It had to be manually wound back down.

Hehe.....glad to hear I'm not the only one that has happened to!

[John W. Love]

Lol, it's me with my questions again... guess I'm a typical inquisitive woman :)

We performed a minor beam alignment last night...and were able to get the beam lined perfectly with the hole burned in the tape by our laser. However, I am curious why the beam being misaligned would affect engraving. I thought that the beam was simply a guide to let you know hmmm I don't know what I thought lol just some sort of guide to use when using the center command for engraving. The laser itself does not ever touch the beam mirror...so why does the beam alignment affect the actual engraving when not using commands such as center? We are engraving the granites with the pieces jammed up in the upper left corner of the machine so that if we need to remove them and re-engrave it's easy to get them in the exact position we originally had them in.

I haven't run another job yet...well I re-ran the text on a piece we are doing for a memorial plaque since originally it came out faded on the right edge near the bottom of the piece...and that did come out better, but I haven't run another job yet. However, I suspect that the beam alignment will have helped because we did the test where you cut 4 squares at the 4 corners after we did the alignment and the 4 squares actually cut out on the first try lol. I had made a template the other day for our roses so we could engrave multiples at the same time and had to print several times before I got all the squares to cut even though I was only cutting 1/4" mdf and followed the settings in our manual which says we can cut up to 3/8" so I assume that's what the settings are supposed to be for.

*crosses her fingers*

Thanks guys, y'all are the best!