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 through 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 through 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 🙂
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!
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.
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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!
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Owner and main author of this website. I´m also the inventor and engineer making up all the crazy custom products for sale.
Comments (50)
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!
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.
Thanks for that, I’ll try that out and see what happens.
Please i have the same problem, i align the mirrors and when I move the laser head to the top right or left the hit is not in the sender is up and right, What should I do? move the gantry?
Thanks!
Look at my earlier reply, you need to shim the gantry between the floor and gantry to lift it a bit.
Hello. I got same problem. Top right corner laser point move up and left. I lifted gantry at this corner but no success. Please help me. What else i can do?
Lift more, remember to zero out the alignment after each shim you add, if not you get old error + new lift as total error. Move to bottom right and center before testing top right.
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!
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.
Followed all the steps and then right at the end the laser quite high instead of in the middle.
I’ve tried everything, am I doing something wrong?
If the beam is high in the bottom left position, your 2nd mirror needs to be lifted, or the laser head lowered.
Hi Thanks for the help , got it aligned but it does not seem as powerful , wont engrave at all and laser I have to turn up to almost max to get anything , please help if you can what I’m doing wrong
Check out the article about proper focus. If you are out of focus the power will go down very hard. Also make sure you are hitting inside the mirror and lens in all 4 corners. Move the gantry around and test-fire to make sure you hit inside the mirrors, and the lens.
Hakan,
I have been following you for quite some time, you have helped me in many ways.
Your website is coming along brilliantly and this new format is alot easier to follow.
I come back here every time i need to realign.
Un beatable. You should be proud.
Hello,
Your article was loads of help thank you! But I have an issue I’m hoping you can help me with.
I bought my machine last week, I had to have a new laser sent out as the first filled with water, I installed the new tube and set the alignments, it worked fine for a few test items yesterday but today I went to use it and it wouldn’t cut. I thought maybe the mirrors needed tweeking but when I tested the first mirror I have two dots on the tape not one like I did when I first tested it. Is is another faulty tube? Thank you
Increase the power if you get two dots. The tube is not in a energized state and can be instable and create two beams. If the two dots doesnt go away on higher power the tube is bad.
Second time using this guide, now with new mirrors and lens I bought ages ago! Thanks Hakan!
Thank you, thank you, thank you! My old K40 has never cut so well! I had a laser head that was about 1.5mm too high which made for a tiny window of steady power throughout the bed. I simply ground down the stand-offs that hold the head to the gantry a bit, realigned, and it working great!
I have watched many videos etc online on mirror setting etc…This is by far the best and easiest if you follow instructions properly. by far the best , will save you alot of time and most of all, FRUSTRATION..\\\\awesome, Thank You for the instructions..
Great info, got every line up, but have a problem: ok lined up all the mirrors,here the problem 3rd mirror at bottom right corner, (furthest point) spot on, when i move it to top right corner, the spot is 2mm to the right. any ideas?
The X is not 90 degrees. You can loosen the coupler holding the axle between the both sides of the drive system, and move the right part a bit down – towards you. and then re-align bottom-right with bottom left again – and then test top right again.
Hello! I have a similar problem. I can follow your guide and do the alignment without any difficulty. However, after adjusting the head in the lower right corner, if i move the head to the upper right corner the beam goes up 2mm.
I already tried to moove up the gauntry in the upper right corner, but when doing this and after repeating the alignment, the mirror 2 follows the movement and continues all the same (up 2mm).
I do not know what to try more …
Only solution is to lift the gantry in top right corner. Lift it more without re-aligning the beam.
Haven’t tried yet, but I’m a bit confused about the head adjustments. It seems to me like moving the head would be tricky. I would think that as long as you are centered on mirror 1, adjusting mirror 1 angle would be sufficient. All other mirrors could be aligned w.r.t. mirror 1. Could you explain why moving the laser head is a more desirable way to go?
You cant bend light. No matter how much you adjust a mirror, you can never resolve a laser head not beeing in line with the mirror, or the 2nd mirror in line with the 1st. The laser head have to move left to right in the same 90 degree angle as center on the 2nd mirror, if not the beam will wander all over the mirror and in the end – miss the lens or hit inside the head 🙂
This is the best guide I’ve seen so far, but for me, one thing is still missing. I still haven’t entirely figured out how the knob screws behave in adjusting the mirrors.
I’d sure like it if you could describe which knob to turn in which direction to get the desired movement.
So, for example, “If beam moves up, turn knob #3 half a turn clockwise.”
Also, I’m wondering if it’s possible that the gantry might be unevenly, imprecisely or improperly set, will it them be impossible to accurately alight the laser beam?
HP, thanks for this guide!
Beam was hitting my 3D printed air assist nozzle when mirror 3 is in certain position causing double lines.
I’ve successfully adjusted my mirrors and now beam hits center of third mirror no matter where it is at.
I have a few suggestions to make this guide better:
1. Please make the first image showing which mirrors are which larger. I know you can click it to make it larger, but IMHO it is critical to convey which mirror is which it should not require reader to click.
2. When explaining how to adjust the mirrors, please include a photo/diagram as to which screw does what.
3. Under section “Part 1 – mirror 1 and 2” in this sentence “Follow each step of the instructions and lick on the button”, I’m sure you meant click instead of lick 🙂
Thanks again Håkan!
Good ideas! Thanks
I am having an issue that I have spent about 12 hours trying to fix with no luck. I will try and explain it properly here.
So… First I aligned Mirrors 1 and 2 that went off fairly well. Then I aligned 2 and 3 in the bottom right and left positions. Took some fiddling but got it to track back and forth and stay in place on the laser head. Here is where the problems start.
Next i moved it up to top right and it is shooting about a centimeter above the previous dot in the center on the bottom right. When it is in top left the position on the head is good but goes way outta whack in the top right and it moves up really fast after about moving up in the y axis about 6 inches the dot shoots up. I have tried correcting it by bumping the tube up and down. If I get the top right fix the bottom right is way out expect a cm too low. It almost seems like there is a twist in my machine but I check the corners and they are square, the rails run level to each other. I have been pulling my hair and getting nowhere. Any ideas would be greatly appreciated. Thanks
Only adjust the tube to hit inside mirror 1, after that you should never touch the laser tube again. If the dot moves up in top right position, that corner is lower than rest of the gantry.
Shim it with some washers, about half of the movement you see, aprox 5mm. Then re-check so the beam is good between mirror 1 and 2, and from 2 to head in bottom position, and lastly test top left-right positions again, use the data you get to shim more or less in that corner.
Hi there,
I’ll start by saying your guide is amazing and I wouldn’t be where I am now without it. When I do the alignment for mirror 3, I can get it in the center perfectly but it is clipped and looking like a half moon when positioned on the bottom right. When positioned on the top right is worse and actually barely left a mark. I’m now nervous to touch either mirror 2 or 3 because I don’t want to make it worse. Any suggestions?
Take a piece of paper and put in front of mirror 1, then mirror 2 and see where it hits the edge. If it clips the edge on mirror 2 you need to adjust mirror 1.
Thank you for replying back!!! I was able to get it centered perfectly! Lots of patience.
I now face a different problem and I’m hoping you can point me in the right direction. I did a test with a square that was 100mm by 100mm. After I cut the square I measured 100mm (x) by 97mm(y). I did contact support for my Laser cutter but all they said was to tighten up the coupler in the rear. I didn’t think that would help and it totally didn’t, I still have the same results.
What software are you using? Some are cutting on the line and the width of the beam sometimes makes parts smaller, and if its only one axis i also think its a belt issue. But try making the box 150×150 and one 50×50 and see if it keeps the error ratio, choose engrave on something just to get lines to measure.
Hi! I have adjusted the alignment on my old Red Sail multiple times. I have a new blue Chinese laser, and I’m stumped. When I pulse without any mirrors covered with paper it will mark my bed material. When I put paper on any of the lenses to try to align it the papers will not mark at all. I’ve adjusted the power of the pulse, I’ve put a whole sheet of paper up in case the beam is majorly off…but nothing…help?
Start with the 1st mirror, put a piece of paper in front of it and try to mark the paper, move on to 2nd, 3rd and then the bed to see where you lose the beam, there´s where you need to check more what is happening.
Thanks for this guide, from mirror 1 to 2 , needed 4 washers, then needed longer screws, then needed more washers to compensate for the screws being too long and not tightening, and its not even perfect yet, still 1-2 mm above and left.
What im saying is this is a very tedious and time consuming, wish ther was a Prusa version of this price/quality
Brilliant guide thanks. My issue is, mirrors 1 and 2 aligned but when i fire at the head it doesn’t even mark the tape. How can i bring mirror #2 to hit the centre of the laser head?
Put a piece of paper in front of mirror 2 in both top and bottom position so you are sure the beam hits the mirror.
If it does, take a larger sheet of paper and start close to mirror 2, pulse the laser and move the paper to the right side to see where the beam goes – and adjust mirror 2 until you hit the laser head. Keep your hands out of the beam and look away when pulsing to prevent any flash backs.
Have a problem with alignment. Have all mirrors align so that all 4 corners hit same spot on laser head. The problem is when I cut it ghost in the middle right side. When I check with tape on head all 4 corners are still right, but about 8″ up on the right side the beam drops about 4mm. Very Confusing. Thanks for any ideas.
You are probably hitting inside the laser head, or the edge of the lens or some mirror.
In the download section on this website, you can find a tool to see if the beam hits in the middle of the lens or not, try it out! Go to FAQ in the menu and then downladable files.
Hi,
many thanks for that perfect guide.
I hit every mirror perfect in the center. But when I move the laser head to top right, the laser spot is 2-3mm left from the center??
Any ideas, what I can do?
Thank you very much
Jochen
Try moving the gantry with the software, if you push it by hand you might move the right side more than the left. It might be a small skew in the gantry too making this, but try with moving the gantry with software jogging first. Second to try is to loosen the coupler on the motor and move the right side 2mm and then tighten the coupler again. (motor and coupler between left and right side)
Many thanks for your help! But how do I loosen the coupler on the motor? Are that the round things left and right of the motor in the middle/back of the machine?
Sorry for stupid question!
Between left and right side there is a axle connecting both sides to the stepper motor. The axle is held to the motor with this coupler, small torx or socket head screws, if you loosen the screws you can turn the axle for one side a bit to compensate for any skew in the movement. Mark the position with a sharpie so you know where “zero” is if you need to go back, or the other way.
ok, i will try!!
Many, many thanks!
AMAZING write up on how to align the machine! Like you stated at the beginning I thought my frame was WAY off. Then I found your site and went through the steps and it was easy as could be. Thanks a bunch!
My stock Blue/White K40 tube hits the first mirror quite low– down by about 4.5mm. I can’t lower the bracket the mirror is mounted on so I assume I need to move the tube itself upwards. The large plastic brackets that hold the tube don’t appear to have any up/down adjustment. Do I unseat the tube from the plastic brackets and place shims under the tube? Or rather, I should ask “What is the correct way to up/down align the tube?”
1st mirror is not that important, the 2nd is though. But if you want to lift the tube – put some shims between the metal and the holders of the tube, use acrylic or wood. Then start over aligning it on the 2nd mirror and go from there.