Mirror alignment – the ultimate guide

Mirror alignment – the ultimate guide

Welcome to the ultimate alignment guide for your laser machine.
This guide has some tips and hints regarding the popular K40 machine type, but this can be used for any laser machine on the market as the science behind movement of a laser beam is the same on all of them.

90% of the errors in laser machines are not skewed or non-square gantrys, it´s bad alignment of the three mirrors in the machine not lining up with each other.
Some of you will have a machine of that 10% with a skewed or non square gantry, but follow trough this guide to the end anyway and you will find a link my other guide how to fix gantry problems. But first, you have to identify the problems by following this guide.

Please read trough the preface about this guide before you start to avoid doing it wrong.
In my old guide i had numerous examples of readers who skipped some parts and ended up doing the alignment backwards. I know it´s tempting to skip a step or two, but please, read everything and let me know if something is not clear 🙂

Did you know! You can hire me for personal one-to-one support trough Facebook messenger/Skype to help you align your machine – click here for more information!

Introduction

This guide will help you align your laser machine to perfection.
It is very important that you follow each step and not jumping around, you will miss important information or details how to identify your machines problems.

Tools you need to complete this alignment
– Any tools needed to adjust the mirrors on your machine.
– Screw drivers, sockets or wrenches to adjust mirror holders.
– Painters tape, labels or paper with adhesive backing for covering the mirrors when test firing.
– In rare occasions, files and drill bits to adjust the holes where mirrors are mounted.
– A pint of beer, wine or a good cup of coffee 😉

How to interpret the results
This guide has a lot of test-firing and looking at the tape/label what the beam does and where it moves. Some parts need you to identify if the beam moves up, down, left or right – when doing this the direction is always as if you remove the tape and hold it in front of you, if the dot has moved right when you look at the tape – you choose right in the sections below.
It does not matter wich way the tape was mounted – just keep it horizontally the same from the mirror to where you look at it.

Preparations
Adjust the tube if needed so you hit aprox. center on mirror 1.
Also, familiarize with the three adjustment screws on the mirrors which screw moves the mirror in what direction. This will help later in the alignment.

Machine locations and centering the beam
Here is a picture of different position i will refer to in this guide, please have a look to see what is what.
When i mention centering the beam, this has nothing to do with quality or power of your machine, it´s just a easy position to remember. You do not have to be exactly center – keep it close to center so it´s easy to see where the next test-fire will go.

Now, are you ready to align your laser machine? Let´s go!

Important details!
This guide has the main function in centering the beam on a mirror – this is super important!
After each adjustment of a mirror, plate or gantry part, always, always move the gantry to the furthest position, adjust the mirror until you hit center and then move gantry up close to test fire.

If you do not do this after every adjustment, you will get the old error + new adjustment as a total error and it will throw you off totally.

Part 1 – mirror 1 and 2

This part identifies the movement of mirror 1, moving up and down (from rear to front) of your machine. Follow each step of the instructions and lick on the button corresponding with your problem to find the information how to solve it.

Step 1 – first fire

– Move the gantry to bottom as the first picture shows
– Do a test fire and have a look at the tape on the 2nd mirror.
– Adjust mirror 1 until you hit center on mirror 2 in bottom left position.


Step 2 – upper axis

– Move gantry to top right position
– Do a test fire and have a look at the tape on the 2nd mirror.

By looking at your tape – did your beam move up or down?

Click on the answer below to see the solution.

Your 2nd mirror is too low.
Make sure the bracket holding the mirror is square and not bent.
Remove the two screws holding the bracket, mark the position so you can put it back and add some shims between the bracket and the gantry so the 2nd mirror is lifted some.

Start over with the alignment and re-center the beam in furthest position and adjust more if needed.

A alternative solution is to lower mirror 1, but do not go that route until you tried the tips above first.

Visual example of movement up.

Your 2nd mirror is too high.
Make sure the bracket holding the mirror is square and not bent.
The solution for this problem is to bend down the bracket a bit if its bent up, which is the most common issue. Second solution is to lower 1st mirror but almost never needed.

Start over with the alignment and re-center the beam in furthest position and adjust more if needed.

Visual example of movement down.

Sweet, your vertical movement is already aligned. You can now go to the next step.

Visual example of perfect alignment.

By looking at your tape – did your beam move left or right?

Click on the answer below to see the solution.

Your 2nd mirror is too far to the left. Loosen the two screws holding the white plate and move it slightly to the right.

Start over with the alignment and re-center the beam in furthest position and adjust more if needed.

Visual example of movement to the left.

Your 2nd mirror is too far to the right. Loosen the two screws holding the white plate and move it slightly to the left.

Start over with the alignment and re-center the beam in furthest position and adjust more if needed.

Visual example of movement to the right.

Sweet, your horizontal movement is already aligned. You can now go to the next step.

Visual example of perfect alignment.

Part 2 – mirror 3 and laser head

Half way there! This part helps you align the laser head in square line with the 2nd mirror. We know the 2nd mirror is in line now since part 1, and now it´s time for the laser head.

Just remember, after each adjustment – re-center the dot on the laser head before test-firing up close to mirror 2 to see where the beam moved.

It´s important that you do not touch the alignment at all from part 1.

Step 3 – bottom right

– Move the gantry to bottom right position
– Adjust mirror 2 until you hit center on mirror 3 (hole in the laser head) in bottom right position.



Step 4 – bottom left

– Move the laser head to bottom left and do a test fire and have a look at the tape on the 3rd mirror.

By looking at your tape – did your beam move up or down?

Click on the answer below to see the solution.

Your laser head is too low.
Mark the position of the three screws on the laser head with a pen or small mark, remove one screw at the time and insert a washer between the standoff and the plate holding the laser head.
Doing this will not ruin the location of the plate, confirm with your marking and adjust if it moved.

Start over with the alignment and re-center the beam in furthest position and adjust more if needed.

Visual example of movement up.

Your laser head is too high.
This is not a common problem and is mostly due to a low 1st and 2nd mirror.
You can try to lower the laser head if possible, but i would suggest shimming mirror 1, 2 and the laser tube with 1-2mm thick washers and start over with the alignment guide.

Start over with the alignment and re-center the beam in furthest position and adjust more if needed.

Visual example of movement down.

Sweet, your vertical movement is already aligned. You can now go to the next step.

Visual example of perfect alignment.

By looking at your tape – did your beam move left or right?

Click on the answer below to see the solution.

Your laser head is too far away from the gantry. Loosen the three screws holding the bracket and move the plate up (if you look at your machine standing in front of it – looking down on the work area). Up – away from you.

Start over with the alignment and re-center the beam in furthest position and adjust more if needed.

Visual example of movement to the left.

Your laser head is too close to the gantry. Loosen the three screws holding the bracket and move the plate down (if you look at your machine standing in front of it – looking down on the work area). Down = towards you.

Start over with the alignment and re-center the beam in furthest position and adjust more if needed.

Visual example of movement to the right

Sweet, your horizontal movement is already aligned. You can now go to the next step.

Visual example of perfect alignment.

Laser head centering

Aligning the machine in horizontal and vertical plane is almost good enough. The last little part is the laser head. Hitting the hole centered is often not enought but close.

Easiest to do this is to use my tool, cut it out from 2mm acrylic or wood and put on the laser head, test-fire in each four corners and look at the tape to make sure your beam is hitting well inside the lens. Too much movement between the corners needs attention.
As you have perfected the alignment between the mirrors i suggest you add small pieces of paper between the mirror and holder for the laser head if you need to do any smaller corrections.

Conclusion

You have now aligned your machine by all means possible. If you still have problems it´s time to look at the gantry if it´s square, level and in line with your bed and machine.
Click here for the old article about aligning, where i go in to adjusting the gantry a bit more.

If you still have problems you cannot solve, consider hiring me for remote help with your machine, or join the facebook group to aquire help from others with similar or same problems.
I´m sorry to say it, but if this guide cannot align your machine, it has some bigger issues and a general guide like this will not cover the problems it might have if i want to keep it quick and helpful for 95% of the users.

Feel free to comment below, contact me or join the Facebook group to learn more!

The old version of this guide is archived – it can be found here if you still want to read it!

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Comments (5)

  • Andrew Reply

    Hello, thanks for your guide. It has proved very useful!
    However, after following all of your steps and getting the laser to hit dead center all the way through to the end of your guide, when I move the laser head to the top right and fired the laser onto the tape then moved it to top left to fire again, the beam moved down and to the right.
    I know this is not part of your guide to check top left but surely it should be firing on the center on top left too? Or is this ok?
    Thanks!

    4 June, 2018 at 15:17
    • HP Persson Reply

      If you upper right corner steps up on the mirror, the gantry is leaning down in this corner. Add some washers between the gantry and machine case and test again.

      5 June, 2018 at 15:45
      • Andrew Reply

        Thanks for that, I’ll try that out and see what happens.

        8 June, 2018 at 14:30
  • Andrew Reply

    Worked like a charm. I also had to carefully bend the gantry in the same manner as you recently suggested to someone on the Facebook page, seeing as the right side of the gantry was too close to the tube. Everything’s lined up perfectly now in every position. Thanks heaps!

    10 June, 2018 at 16:04
  • Ian Maxwell Reply

    It worked a treat. I spent 4 days trying to align my mirrors without any success. Following this I am now up and running in a little over 2 hours.Many thanks.

    19 July, 2018 at 00:26

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