Laser engraver newbie.

[Ron Whiter]

Hi, we just got a laser engraver at our comany, chinese model 9060 (manufacturer unknown) and I've been tasked with learning everything about it and figuring out how to get it to do what we need to do (which honestly isn't much, mostly cutting out acrylic parts for computers) I've learned about as much as I can about it, I've adjusted the laser path, etc. and I'm looking for a bit of advice if anyone cares to chime in to post some commments on the following bits:
1. The red beam and the co2 beam don't seem to line up at all, I know the co2 beam has a decently clear path (tested path with acetate sheets) but I haven't had any luck with both of them coinciding, is this typical?
2. the beam when cutting seems to have an exceedingly large path that it cuts I've tried moving the table up and down to see if it's the focal length, but it doesn't make a whole lot of difference, any ideas would be greatly appreciated.
and lastly, I've tried engraving and cutting 1/4" plexi and it seems that the edges the unit cuts are always rather bevelled, I was hoping to see a "laser fine" cut and I'm not sure what I was to expect doing it. Is this how it usually cuts? Should i do multiple passes with a lower power or is there something wrong with the focus that I should look into.

Thanks to everyone who takes the time to reply to a noob. Your comments are appreciated.

[Edward Brown]

Possibly the lenses, make sure everything is clean. Sounds like a focus issue, some machines are more sensitive than others. Moving it up and down will narrow the focal point, do you use an auto focus or a focus tool?

[Gary Hair]

Ron,
You have two issues that are related. You have an alignment issue. You must get the two beams aligned first then you can work on the angled cut. The angled cut is because the beam isn't hitting the lens in the center and is actually coming out at an angle. Technically this is alignment as well, but not exactly.

I have no clue how to adjust it on your machine, but I can almost do it in my sleep on my machine. One of the problems with the Chinese machines is the lack of support from the manufacturer - you'll have to find support from other users. I guarantee that others have had to do an alignment, you just need to find them. Try searching "chinese laser alignment" and see what comes up.

Gary

[Ron Whiter]

Edward, As far as focus, the only tools I have are my eyes and hands :D I was given no other information other than what came with the unit and all the instructions are in Engrish. I've already replaced the focus lens and cleaned all the mirrors with isopropyl. I had noticed after the first couple tests that the focus lens was shattered in 3 (alot of smoke being produced too) so after replacing that, it actually started to cut again and that's when I encountered the wide/bevelled cuts.

Gary, I was responsible for doing the research and I encouraged the company to go with Epilog, but apparently budgetary concerns of 6K vs 35K were the issue.

So far, I've got the co2 beam going perfectly from the source to the head, then there is a downward mirror that shoots the beam down into the focus mirror, then another piece that attaches onto that is just a cone shaped piece of metal with no apparent purpose,

new question is, should I got back to the start and tinker with all the mirrors so that both the co2 beam and the red dot are striking dead center on all the mirrors? Or if the beam is making it to the head, is that just a cosmetic thing? the red dot and the co2 beam don't seem to strike the same place on any of the mirrors, but seemingly seem to end up in the same general place.

[Dean Novakowski]

Sent you a pm

[Dave Lock]

Hi Ron,

All the Chinese machines seem to be very similar in their construction. You may find this video useful regarding beam alignment.
http://www.hxlaser.com/support/home.htm and look at the video link for the Rabbit SE Type

This shows the correct beam alignment for the CO2 beam. By the time you have gone through this process you'll have a pretty good idea how to go about setting up the red laser.

Regards

Dave.

[Mike Null]

I suggest a search here on lens cleaning. Do not use isopropyl alcohol. It contains water. Better to use lens cleaner specifically for your lenses. If you can't find any use Everclear alcohol--you can get it at the liquor store. In a pinch you can use standard acetone and cotton swabs.

[Tim Bateson]

...then another piece that attaches onto that is just a cone shaped piece of metal with no apparent purpose,...

That sounds a lot like the manual focus tool I use with my Epilog. Attached you raise/lower the table until your work piece just touches it, then you remove it.

[Todd Suire]

This sounds like it's possibly an air assist cone like the one I have with my Versalaser. I've been told it's only used when cutting, to protect the lenses.

I've had issues making sure it's lined up correctly so the laser and red-dot pointer fire all the way through.

The smoke on the lenses issue sounds like you're not getting enough air flow across the material that's being cut; in that case the smoke and heat could damage the lense.

Just my newbie .02 worth.

[Ron Whiter]

Ok, I retract my comment about the cone having no use. I did not see the air tube that was hooked into it until I had to replace the focus lens because after about 30 seconds of cutting at 100% power (80w) I head a crack and found the focus lens had turned white and was broken in 3.
So the cone shaped device is screwed onto the focus lens holder, it's not something that would be taken on and off, compressed air blows through it while the laser is operating. I'm assuming to clear debris off the workpiece while lasering.
Is there a surefire way to tell that you're at the exact correct focal distance?
I'm going to re-do all the mirrors starting from the back and working my way forward.

[Ron Whiter]

This sounds like it's possibly an air assist cone like the one I have with my Versalaser. I've been told it's only used when cutting, to protect the lenses.



In that case, I won't remove it :D Although I did take notice that the tip was a little bent, I should probably flatten that out.

[Larry Bratton]

I suggest a search here on lens cleaning. Do not use isopropyl alcohol. It contains water. Better to use lens cleaner specifically for your lenses. If you can't find any use Everclear alcohol--you can get it at the liquor store. In a pinch you can use standard acetone and cotton swabs.
Also good to drink in VERY small amounts (do this when you can't figure it out or translate the Chinese) Good Luck! :)

[Dave Lock]

Ron,

If you watch the video in the link above all will become clear. At around 24 minutes you will see the final alignment of the beam and how to centre it to the air assist cone.
Then you will see the correct method of setting the focus.

You should have been supplied with an acrylic square (setting gauge), place a piece of paper on the bed, set the height from the cone to the paper to about 20mm. Test fire the laser using the test button. Note the size of the dot. Raise/lower the table until you achieve the smallest dot from test firing. When the dot is at it's smallest the focus is correctly set. Offer up the acrylic square to the cone and note where it aligns.
From now on all you need to do is set the focusing using the gauge prior to each job and you are good to go.

Regards

Dave.

[Gary Hair]

Is there a surefire way to tell that you're at the exact correct focal distance?

The best way is to use a 6" x 1" piece of black anodized aluminum, it will engrave with the best resolution. Place the aluminum with one end on a 1" block and the other end on the bed - tape it in place. Raise or lower the bed so that the point where you think the laser is in focus is about the halfway point on the aluminum. Laser a line from one end of the aluminum piece to the other. The point where the line is at its narrowest is where the beam is in focus. Measure that height from the bottom of your cone and cut a piece of acrylic, aluminum rod, dowel, etc., to that length. You could do the same thing with a piece of wood, cardboard, paper, etc., but the aluminum will laser much sharper and you can be assured of it being truly in focus.

Don't bother doing this though until you have the two beams aligned and you also have them both dead center on the lens. If you are off center you won't be focused at the right point and when you finally do get it centered, the focus will be off.

Start from the start and end at the end...

Gary

[Gary Hair]

You should have been supplied with an acrylic square (setting gauge), place a piece of paper on the bed, set the height from the cone to the paper to about 20mm. Test fire the laser using the test button. Note the size of the dot. Raise/lower the table until you achieve the smallest dot from test firing. When the dot is at it's smallest the focus is correctly set.

Dave - with all due respect, that's a horrible way to try and determine focus. If you test fire for a millisecond longer or shorter you will get a different sized dot. There is no way in the world you could consistently test fire and compare dots.

Gary

[Dave Lock]

Dave - with all due respect, that's a horrible way to try and determine focus. If you test fire for a millisecond longer or shorter you will get a different sized dot. There is no way in the world you could consistently test fire and compare dots.

Gary


Gary,

I have been using the test fire button for this every time I've had the head apart for cleaning. Firing multiple shots at the same height has always produce consistently sized dots.
However, Your method does present a good idea, I'll certainly be giving it a go.

Thanks for the tip.

Dave.

[Ron Whiter]

I think my main issue here is that I can't see the focusing lens, it's inside a housing so I can't exactly tell where the beam is firing on the lens (if I have it centered) and of course the red dot is just shy of useless, not even sure why it's there (I suppose to center the air assist cone on the item being engraved, but really how accurate is that?) The laser itself is perfectly bounced from mirror to mirror, I'm quite certain I am getting the full power of the beam (putting acetate on each of the mirrors/holes in turn and taking note of where the hole burns) but there's no possible way with the reflector mirrors configured the way they are that the red beam can make the full journey from the back of the unit to the to the laser head. It never manages to hit the second mirror no matter how I wiggle/bend, curve the weak aluminum piece that the red dot's main mirror is set on. So I gave up on the red dot for now, cutting results are looking pretty good on some scrap 1/8" plexi I found laying around, the actual cut is fairly straight, but there's still some melting on the top. I guess the only other question I have is, will the laser ever have the precision of a vinyl cutter blade for example, with no collateral damage to the product being cut?

Thanks to everyone with their ideas and assistance.

[Dave Johnson29]

I think my main issue here is that I can't see the focusing lens, it's inside a housing so I can't exactly tell where the beam is firing on the lens


Ron,

Are you using masking tape over the mirror windows? Set the power to low and make a quick zap and see that the burn is centered in each window. If the burn is centered in the final window then it should be hitting the center of the focus lens.

Start with the mirror closest to the laser output, then the next, then the carriage at the closest end of travel and the carriage again at farthest end of travel and finally the mirror to the lens. Adjust at each step to move the burn dot in the center.

[Ron Whiter]

I wanted to report that I managed to get almost razor fine cuts without bevelling, however in order to do so I was forced to remove the air assist nozzle because the length of the nozzle (total of 2.5" from the focus lens) made it impossible to EVER achieve a perfect focual point, the focal point needed to be a full half inch closer in order to achieve the precision it should have. I have no idea how to make the nozzle fit and make the focal point correct, I took measurments of each piece and no matter how I adjust the locking rings or how many or how few turns I tighten each piece, there's no possible way to achieve focal point with it on.
So I took it off the the time being, I suppose I can make a metal tube that will blow air accross the workpiece in a a more useful manner, and I still can't get the red dot to match the co2 beam, but I no longer care that much about it.

Anyone know how to measure or determine the exact focal point on a 21mm plano-convex lens? (63.5mm was written somewhere in the documentation which is 2.5" which produces terrible results.)


Thank you everyone, fyi this is a chinese model 9060 from Shenhui in case anyone else needs to reference similar issues.

[Dave Johnson29]

Anyone know how to measure or determine the exact focal point on a 21mm


As has been stated here, black anodized aluminum is ideal. I use a 2" x 6" piece laying flat on the table. I draw 1-1/2" long straight line at about the middle at around 3" Move the table to the 2.5" start point.

I burn the line then move the line 1/8" and drop the table 1/8" and burn again. repeat until the line is visibly fatter.

Move the line back to 2-7/8" and raise the table to the start position. Repeat above process but raising the table.

Examine the burns with a magnifying glass and find the optimum line quality. That's focus.

[Ron Whiter]

@Dave
Thanks for the input, I was hoping there was a more simple method other than the fallability of my own eyes. Either way I think I got it as close to perfect as possible. Just need to rebuild an air assist for it.