Laser firing 2 dots out of the brand new tube

New 80w laser machine and 3 new tubes from the manufacturer and it’s making 2 dots out of the tube. I don’t get it, why is this happening. I’ve read several places and people having similar issues just ordered new tubes… this is the third tube and I installed this one this morning

Edit: it really looks a circle split in half.

The lens / window of the laser tube (the small glass lens on the end of the tube where the laser beam exits) could be dirty or damaged.

It’s a really careful process to attempt to clean that lens. Denatured alcohol spritzed on to it and air dried is a start. But visually inspect it first.

However, if you’re saying that this is the third tube that has done this, there’s a better chance that your lens in the lens holder of the gantry is cracked or damaged.

We did buy a new lens and may have had it in upside down.
However it still takes 2 passes to cut anything.

If I put tape directly on the first mirror it’s still putting 2 half circles on the tape rather than a pin point dot in the center. I’ve noticed that the beam doesn’t pass through the brass end of the tube, just kinda dances around the edge of the opening.

Could a bad connection or low power from the power supply cause any of this?
If so
I can re-do the connection, but how would I test the PSU?

I’d love to get to the point that I can just align the mirrors, run a ramp test and be be done. Seems like we’ve been dialing this thing in since we took it out of the crate 3 months ago.

My wife wanted to do it and I think she has bit off more than she can chew, and maybe for me too. Little to no direction in the packaging on how to operate it and nothing is cut and dry.

I feel like I need to go take a CNC course at the local vo-tech center in order to get my head wrapped around it

Where are you getting your tubes? What brand?
If you have a split beam coming right out of the end of your tube then it’s faulty. Does it look like image 01 in the attachment instead of 00?

Transverse modes:


Looks like the 01, like 2 half moons. But one side will burn through the tape on a pulse test, the other side will just make a mark (at 15% power). We can get it to cut but we have to turn it up to 80% power to get it done, this 1/4 wood we’re dealing with

The tubes are being shipped from Tennessee but the unit itself came from eBay with a terribly misspelled manual also with bad punctuation and grammar

We have been reaching out to the seller and they have provided both replacement tubes so I am unsure of where they are coming from other than the shipping label says it’s coming from Tennessee.

Does it make difference when you focus teh head up/down? It looks like you have the beam out of the nozzle center. The beam reflects from the copper border of the nozzle and makes a “shadow” dot. When you are moving the head up and down, the shadow moves far/near from the original dot. Maybe you have incorrect beam setting, that is not perpendicular to the surface (and parallel to the nozzle/head). Or at 3rd, it could be too narrow nozzle for the beam - this indicates that you have wrong focal length or the lense is upside-down.

He says that’s what the beam looks like coming right out of the tube, BEFORE any mirrors.

That should not matter - the lense should “center” the beam to the focal point. The problem is, if the nozzle is in the way. At the focal point ALL the parts of teh beam come together to one point, so there’s no reason for the beam to be splitted.

Edit: I’d try to focus the beam, what does it on the surface. If both of parts are parallel, they should meet at the focal point anyway. Of course it’s not good, if the new tube makes weird beam.

The beam is split at mirror 1, 2, and at the nozzle. If I remove the tape I get wide and burnt looking cuts. I’ve ran a ramp test and set the distance from the table to the nozzle, raised air pressure on the air assist, got an in-line fan to remove the smoke, still takes 80% power to make a cut. If I don’t do that it looks like it engraves

If I align the mirrors, I can successfully put the 2 dots in the center of mirror 1, 2, and the nozzle. I even set the mirrors in the housing to make sure it’s centered out of the nozzle, then ran a ramp test to find the cleanest cut. On 35% it just burns the wood during the ramp test as opposed to cutting, so really I can’t even perform a good ramp test.

If I go to cut a project I don’t see the split beam on the wood, but it’s just a wide burn as opposed to a clean cut.

Is there a certain distance the nozzle and lens should go into the piece that holds it??

I keep thinking I have a connection issue.
I should note that the machine is running off a 75ft extension cord because I haven’t ran electricity to the out building yet.

It matters. A split beam coming out of the laser tube is trash and negates one of the basic expectations of a “laser beam”.

It is certainly a billboard sized message indicating that something is wrong.

With this being the third laser tube displaying the same symptom, I would be willing to wager $1 that the problem is something else.

My guess or at least the place I’d start with now is the laser PSU. Maybe it is failing to strike the tube adequately and the ignition is only partial.

Is there a testing procedure for the PSU?

What gauge is your 75ft extension cord and what all are you plugging in to it?

That extension cord is asking for problems and could very well be the culprit.

I run my machine, chiller, compressed air, extractor, and air dryer on 4 separate branch circuits all no more than 20’ from my main breaker.

You have to be getting some major voltage sag especially if that extension cord isn’t 12 AWG.

12 gauge cord

Running a 3 way splitter, 2 surge protectors, machine, blower fan, air compressor, computer workstation, and a light.

My fear is that sag in power has done damage to the PSU.

Sometimes low voltage can do damage to electrical circuits.