Alignment or something else driving me crazy!

I’ve got this issue with my laser and cannot fix it.

Image is rectangles, the Left one is the back left of the machine, the right is the Front right.
Image if circles correspond to the position in the machine, as you can see the back left is a terrible cut.

You can also see single pulse dot tests and how it varies across the machine.

I have leveled the tube, checked alignment like 10 times, putting tape over the mirror the pulse dot hits same spot front and back, left and right and in all 4 corners of the machine at the head.
The front left is lovely and clean and cuts right through easy, closer I goto back left cut gets worse and worse and doesn’t cut through.

I would assume alignment issue but I’ve checked and checked, now I don’t know what to do.

It sounds like your machine bed is not flat.


It is, I checked that also. all 4 corners just touch the height setting block. the bed is on 4 adjustable sprung bolts so is easy to set it.

Then there is something with your focus anyway that does not fit, and it is very wrong, judging by your image

1 Like

Yes something is very wrong but I have no idea what. everything checks out apart from the cut.

Even doing a ramp test, the front right is a nice thin line, the back left is like a double thickness line (15% power)

What is ‘level’…?

It appears there is an alignment issue from the image…

Why did you mess’ with the tube?

I don’t know your machine, but I have a ‘blue’ one that’s 50 watts. The tube isn’t ‘level’ it rests against the frame for square… is this what you mean?

Just trying to clarify the chain of events…

The both images open to the inside of the machine and the ‘break’ is always furthest from the ‘end’ in the Y direction. At the rear it’s closer to the front, at the front it’s closer to the rear.

I’m assuming that laser is firing as it makes the rectangles…

I would think this means a major miss alignment to effect the optics that severely.

How close is the beam at both extremes at m3?


I levelled the tube to the machine, the machine sits 0.1 degree out of true on the floor and the tube is now the same.

reason I messed with the tube was it was hitting the mirrors very low and the final mirror was impossible to get aligned, so I raised the whole tube as well…Just to be clear this problem was before I moved the tube, this was my first step in aligning everything.

I don’t get why the closer I get to the tube the worse it gets, I would have thought the further away would cause an issue.

i have a red/black laser 1200x900 100w. tube at the back firing in the back right corner.

I cannot see what could be so far out to cause this. just checked again, pulse hits same place on the head (at mirror 3) in all corners of the machine

Unfortunately, this is not always the right way to do it. It is correct IF the whole gantry is 100% in level, but it is unfortunately very rare. I can well imagine that with your big machine, the problem is proportionally bigger to the smaller ones.
But next to that, when you write that you just hit the spot on mirror no.3 all over, then in this case there is only the nozzle left.
It is very mysterious.

1 Like

Have you measured distance from laser head to material at all corners?

It’s indicative of the beam not square in the 3d space. I guess as long as you can raise it square, you should be ok…

Before you moved the tube, the same issue existed? My reading is that you raised it before the tube replacement… and it was working before.?

Sorry, I’m suspicious about rotating the tube length wise by the 0.1 deg…

It being square to the ‘floor’ may not be true to the frame… but we’ll assume that’s ok for now

I would assume that’s the most mis aligned…

Have you done a vertical alignment check?

You might see it that way. It appears that the beam is not hitting the lens in the same spot.


1 Like

Yes, Measured from the gantry to the bed and from the nozzle tip to the bed/material.

I did a job the other day that used the whole bed and noticed the cut was really bad towards the back left, so I started to check the alignment. going back to square 1 with checking the tube was aligned with the machine case was my first check. I moved the front end up about 1mm, nothing much changed here.

I changed the mirrors and put in a new lens, problem is still there.

I’ve checked bed for level with the head. checked mirrors with tape and pulse over and over again, they are as close as possible, dot is almost exactly on top of the close dot.

I also just removed the nozzle and did some circles…

I don’t get it,

Oh and yes vertical check on head also, and spot check through Z axis

Question for me then is when do you first see evidence of the problem in the chain? Assume you won’t see variation at mirror 1. What do you see with dot test at mirror 2 between short and long distance? If no variation, what do you see at mirror 3 at 4 corners?

The first break in the chain should indicate source of problem or at least lead the way.

1 Like

The claim is that it is aligned…

The results seem to indicate differently as you question.

The obvious issue is the back/left and front/right

Shots at both of these would be most beneficial. Same target, two shots.

I don’t mess with tape for targets. I draw them up in Lightburn and cut them out of watercolor paper.
They fit snug into the hole in front of the mirror… the tab is to remove them.




I agree completely, the results do not agree with the spot testing.

I will take photos of the tests.

Not sure if I can post a video???

You can’t generally unless it’s small. I put it on google drive and post the link here.
Ensure you have the links access for ‘anyone with link’…

I ‘cut’ out a bunch of targets and keep them around… Make one and use the ‘array tool’

We’ll stay ‘tuned’… :crazy_face:


The Machine

MIrror 2 close to tube

Moved back for 2nd mirror 2 spot

2nd spot on mirror 2 furthest point from tube

Mirror 3, closest spot
Uploading: 20220315_172455.jpg…

Moved for 2nd mirror 3 spot
Uploading: 20220315_172542.jpg…

2nd spot on mirror 3
Uploading: 20220315_172623.jpg…

4 corners

Uploading: 20220315_172702.jpg…

These are from my 50 watt, and I’d expect your’s to be a little larger, with a more powerful tube… Mine are smaller, I think…

The following are all two ‘pulses’ near and far…

Left is m2 close to front and close to back,

next is m3, closes left and max right.

Third is on the ‘down tube’ same as m3 left and right…

Can we get you to give us a ‘light burn’ or spot on m1, straight from the tube?

I’d like to see the beam ‘layout’ there I’d like to determine a mode.


this is the mirror 1 straight from the tube…

should it be a ring? or solid. only a short pulse at 20%

checked alignment again, all 4 corners are pretty much spot on. even checked with old mirror in and tape on the actual mirror, hits same spot front right and back left corners…

Truly lost now!

If the tube is producing a ring then the lens can’t generate a high energy focused beam no matter how hard you try to focus it.