Cannot align my new laser

Community Laser Talk
1

Hey everyone,
I am having a nightmare. I had a K40 and loved it. I had to align it once or twice and it was easy, however, I bought a bigger laser.
It’s 600 x 400 so not enormous but gives me lots more room than the K40 I cannot align the laser.

If I explain what I have been doing it might explain so someone can help me solve this issue as I want to pull my hair out (what’s left of it) and scream.

So if I call the mirror nearest the laser M1, the Mirror on the X-Axis M2 and the Mirror on the head M3 I will hopefully be able to explain my issue.

The laser to M1 is approximately in the centre so I move to M2, place tape over the mirror and fire a pulse, I use the controls on M1 to align the beam to the centre of M2.

I then move the X-Axis rail to the rear so M1 and M2 are as close as they can get and fire a pulse, they don’t align, not even close so to make the adjustments I am supposed to use the adjustments on M1 again. This means that the alignment at the bottom left is now not centred so I go around and around in circles adjusting and testing until I realise that I am completing the same actions and hoping to get different results which I believe is the actual definition of madness.

What am I missing, this worked on the K40 but there was far less travel distance so I guess the misalignment was not as evident.

Any help is greatly appreciated and if someone can explain why making adjustments to the same screws would have different results based on where the Rail is I would genuinely like to know.

Cheers
Minki

2

Split the alignment process for M1->M2 into 2 operations:

  1. getting the laser to fire at the same position of M2 for both near and far placement
  2. getting the laser to fire at the center of the M2

Changing angle of M1 can accomplish the first. It could give you the illusion of accomplishing this for one position of the second. However, you can’t accomplish both using the controls on M1.

Basically the first operation is about getting the light beam parallel to the motion of travel of the M2. You won’t be able to both center and make parallel using the same controls since they’re independent goals.

So I’d suggest:

  1. Get laser light parallel to motion of travel using M1 controls. As long as the laser hits at the same point both near and far parallelism has been achieved.
  2. Get laser light centered to M2 by physically moving M2 until the laser is centered.

There may be some back and forth on this as adjusting one can impact the other but you should be able to creep up on it.

3

Thank you very much. I managed to, kind of, get the laser aligned. I cannot get the dots in the center when at the bottom left and back left or at the bottom right at the moment but I did have them hitting the same spot briefly before I had to stop testing so now I should be able to start making adjustments to mirror 2 when I get time to get back out there.

4

So, I have the laser fairly well aligned, I think, I have the first mirror to the second mirror almost hitting the centre at both points front and back. I have mirror 2 to mirror 3 which I can’t quite centre but both points are reasonably centred near and far.

The problem is that the laser isn’t cutting evenly over the whole bed, at some points the 60W laser cannot cut through 3mm birch ply at 92.5% power at 8mm per second. It gets close but it just doesn’t make the full cut.

I am not sure what to do or how to move forward. Do I need to get every point fully centred?
Thanks for any help and suggestions.

5

Is the burn dot at the same spot both near and far? If not, this is problem. Burn dot must be exactly colocated, and ideally centered.

Make sure that distance from material to lens is exactly the same at all corners of the laser. You may need to relevel the bed.

This could likely also be due to the M2->M3 alignment issues you’re having causing the light beam to shift at different positions of the machine. If the issue is most obvious between left vs right side of the bed then issue is likely in the M2->M3 alignment.

You also need to confirm that M3->lens alignment is perfectly straight down the lens tube. This is where centering M2-M3 alignment is helpful. Note also that the location of the M3 mirror may not actually match the opening in the laser head.

In practical and simple terms, yes. There are of course nuances to this but not really valuable diving down when you’re just trying to get your laser working efficiently.

6

Thank you so much for your swift reply. I will try and get the points fully centered tomorrow and report back.

7

So, for love or money, I cannot get the laser aligned. I have had Mirror 1 to 2 aligned, then I thought I would just take a look at the mirrors.

I hadn’t done it because the laser was new, however, they were filthy, tarnished and had scratches so I replaced all three with Copper mirrors and replaced the focus lens just to be sure.

So that explains why the power was so down when there was some alignment but I can get M1 to M2 to hit the same spot the whole way down the rail but I cannot centre the point. I can get it to the same place but then when I try and centre the spot it separates again.

Then when I try to work with the spot slightly off centre but hitting the same spot the length of the rail, I go from mirror two to mirror 3, lets say that the first spot is too far to the right and as I move the rail further away the spot drifts right.

I don’t understand how I get the beam back to the left (I know I can loosen the right screw but that would adjust the position of the beam at the front) other than the diagonal screw so I adjust that and then the top screw for down and can centre the spot at the front.

After I move the rail to the back the spot drifts to the right again which means the beam is not travelling in a straight line. The problem I cannot seem to understand is once the beam is centred at the front and still drifts to the right how do I adjust the beam to the centre?

I have watched at least 15 youtube videos about alignment and no one seems to be having the same issue in that the beam is off, you centre it at one point and its off, you centre it at the other point and its off.

Could I have an issue with the physical alignment of the mirrors?

I often work out where the beam needs to go by holding my arm out and every time I end up here I feel like I need to move my shoulder which is essentially where the second mirror is like the mirror needs to turn.

Also on YouTube someone says you do not need to centre the mirrors until mirror 3. I think this information is wrong based on the other videos I have watched and what I have seen here so should I discount his tutorials?

Sorry for so many questions and my inability to explain what is happening. I will try and film the process tomorrow and perhaps that may help explain what I am not able to.

Cheers
Minki

8

How are you trying to center the laser? Are you physically moving the location of M2 or possibly M1? If not, you won’t be able to center. The angle adjustment screws on M1 can only change the angle of the beam, not the centering.

The mechanism is the same. Screws for getting the dot to hit at the same spot, but physical repositioning of the mirror to center.

I’d suggest starting over. Reposition all screws so that they’re roughly at the center of travel for each screw. Going forward, never touch the diagonal screw. Use only up-down and left-right adjustments.

To reiterate, use screws to get light parallel. This will result in laser hitting same spot at front and back mirror positions. Then physically relocate mirror to place the mirror along the laser line, positioned at center. This is no doubt finicky.

Not exactly following. This is exactly what you have. Mirrors are not physically aligned. Or if you mean somehow that the mirrors are somehow situated in a way that they cannot be aligned it’s unlikely or at least unproven at this point. Usually physical problems would result in bed level issues.

Will it work without centering? Yes. The alignment is somewhat achieved. However, you’re likely to have reduced power and at larger risk of clipping the beam.

Don’t distress. This is not an easy process and is very very finicky with lots of frustrating adjustments… many times being 2 steps forward and 1 step back. Many times you’ll make progress but then realize you’ve hit a roadblock because of a physical limitation of the adjustments. The good news is that physics tends to win out and you should be able to creep into an acceptably tuned setup.

9

Thank you so much. I think I lost patience today as I felt like I was going round in circles. I will start from scratch tomorrow at mirror one and get the mirror moved if necessary then move on.

Yes its incredibly frustrating and not knowing what I don’t know I tend to second guess most of my moves.

Thank you for your help and advice I really appreciate your patience.
Minki