Mirror 3 alignment

Cut this out of acrylic, put tape on it and stick it on the nozzle :slight_smile:

Beam Checker 2.lbrn2 (12.2 KB)

Yes, it’s from Russ…

where can i purchase acrylic at?
I bought a .25" 2x2 sheet of birch plywood from home depot to try and do the file cards.

From everything I can tell, everything is square. Lens is curved side up like all the videos say…and its flat with the ring on top.

How do I fix a crooked tube? Order a new tube?
I really appreciate ALL of the help and replies. This has been a frustrating experience all the way around and disheartening as well. I get anxiety from it and just don’t touch the laser for a month…I read and read and read…and watch videos…and have a lot of great ideas on things to make…but it seems I can never get to THAT POINT to where everything is working as it should.
Is there anyone that does house calls to set everything up properly so I can focus on just learning LIGHTBURN and make the projects I want to make? Again, this has been a frustrating process and I wish I had either A) Bought a more refined laser or B) not purchased one at all.

again…I truly appreciate all of the help and advice.

I think the answer to both of those depends on what part of the world you live in.

If you give your aproximate location maybe there’s someone “in your neighborhood” that can help.
Or sell you some acrylic.

Amazon sells acrylic and Tap Plastics is where I get a lot of mine.

I’m in SE North Carolina.

I’ll check amazon for some acrylic? Any particular thickness?

You can get 0.093" (about 2.4mm) acrylic at Lowe’s can’t remember which. It’s about 9 bucks a sheet and is good to get started with. Make sure you get acrylic, there’s lots of other products out there at these places that sell sheets of plastic that shouldn’t be cut with your laser.

:slight_smile:

3mm or 1/8" is handy for lots of stuff so that’s probably a good choice. For that focus doodad it doesn’t much matter.

No advice for help in NC. That’s well out of my service area. :slight_smile:

Atlantic Ocean is nicer than the Pacific…LOL

This is important advise here.
Some plastics don’t cut well at all and some produce extremely nasty fumes that eat lungs and metal parts of your laser.
Genuine acrylic (methyl methacrylate or “MMA”) is what you want.

I watched the video posted about mirror alignment. I think it’s a bad approach technically. The idea is to align the beam produced by the tube to come out the lens to do the work. Align the tube to the mirrors sequentially from 1 to head. Once mirror 1 is aligned to mirror 2, it will never have to be touched again.

When you align it from the work to the tube, any adjustment in mirror 1 will change mirror 2s point and of course, the heads mirror. This seems bassackwards to me. Of course he never did show it working or show how to align the tube.

It might be good to watch Beam Setting for Beginners Part 1.

Here’s Boss Laser Mirrors Alignment Instructions

They also start at mirror 1. Maybe it’s not as aligned as you think…?

:smiley_cat:

I watched the beam alignment video part 1 and part 2. That did make a lot more sense…he didn’t touch his screws for mirrors at all! Here I’ve been doing the screw adjustments the whole time!

I just gotta figure why my beam is not perpendicular or vertical…

I adjusted screws to get me back to a nice small Dot instead of the half moon arc I was having.

I did a ramp test and found my focal length to be exactly what Omtech sent with the acrylic focal gage.

But I do see double arcs in the circles of the file card. I still have to get some acrylic to do that other test.

Thanks again everyone. Keep replies coming

If you go up to post 25 I showed a picture of a little lump of clay that I use instead of the acrylic thingy.
I just press a little flat piece to the table, run the nozzle down until it touches the clay, plus another mm or 2 down so the nozzle makes a good imprint. Hit the pulse button and you can see exactly where the beam hits relative to the inside of the nozzle.

Ok…gotta either get clay or acrylic…

But if it’s off (which it probably is)…how do I fix it? Do I adjust the screws on Mirror 3…or re-align the beam from the laser tube by adjusting it?

You need to check the alignment at the inlet hole for mirror 3 with some tape and a pulse. If the beam isn’t hitting very near the center of the opening then you need to adjust #2 until it is… If it is hitting near center then you need to adjust #3 mirror to get it pointed straight down the nozzle.

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Most of us don’t disassemble the entire optical path like he did.

When you have gotten mirror 1 set, it should not need to be touched again, if properly aligned. Same with mirror 2. Never go backwards, that affects every mirror from there onward.

My machine was off vertically in the Y axes from the factory, much further than yours in the photo. I cut and built a bunch of stuff with it off kilter. It showed no signs of the ‘crescent’. So in my novice opinion, I think you have an issue elsewhere.

Hanks idea or something similar might help rule out z axes alignment issue. On that machine it’s difficult to really adjust the head properly.

I use targets that I cut out of paper and just stick them in the hole for mirrors 1 & 2. Used the same idea for the target head. Make yourself something like this 18.5mm-tabbed-targets.lbrn2 (112.8 KB) for targets. Just cut then out of drawing paper and they stick in the hole, no adhesive or anything… I just cut it where is doesn’t quite make it thought the complete cut.

Russ’ method is a more logical process, at least to me. He’s got a ton of videos out there. I just ordered his ‘rack and pinion’ belt system. I have gotten good results in a very short period of time. I can pretty consistently produce 0.1 mm dots using Russ file dotSize.lbrn2 (4.8 KB). I use it to run on test material for engraving. It’s pretty small in size, so use the ‘zoom to frame’ icon. You also need to enable ‘pass through’ in the cuts layer.

Take care, good luck :slight_smile:

Heh, thanks for posting that. I forgot about those little Russ targets.
I just swiped a little stack of small “post it notes” off the wifes desk and been using those for a while. :slight_smile:

And of course when you do this you will also note the shape of the burn mark on the target to see if the problem appears to be “upstream”.

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Takes about 2 minutes to make them up in Lightburn. :slight_smile:

Yeah, but it only took 10 seconds to steal a stack of post it notes from the wife. :smiley:
Next time I’m set up for doing paper stuff I’ll burn a sheet of them while I’m at it.

You can take the nozzle off, get the bed to the tube. Use a pencil to scribe around the tube. Fire it and see where it lands :slight_smile: At least a cheap look. You should be able to tell how far off you are.

Do it at the front right and at the back left, min and max laser beam travel distance.

I got this today from Lowes. IS THIS SAFE?

I definitely don’t want any toxic fumes…or to mess up my laser. It’s only .080" thick…

Says Acrylic…