Welcome to the ultimate K40 mirror alignment guide for your k40 laser cutter machine.
This guide has some tips and hints regarding the popular K40 laser machine type, but this can be used for any laser machine on the market as the science behind a laser mirror alignment 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 about K40 laser alignment 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 🙂


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.

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!

Time for a new set of optics for your laser machine? Lens & mirror kits starting at €49
Quick delivery in EU with stock in Sweden!
Check out Hawklaser spare & upgrade part store here!

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.
k40 mirror top top

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.
k40 mirror top bottom

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

Visual example of perfect alignment.
k40 mirror center

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.
k40 mirror 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.
k40 mirror right

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

Visual example of perfect alignment.
k40 mirror center

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.
k40 mirror top top

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.
k40 mirror top bottom

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

Visual example of perfect alignment.
k40 mirror center

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.
k40 mirror 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
k40 mirror right

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

Visual example of perfect alignment.
k40 mirror center

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.


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.

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

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

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Andy Frost

Thanks for the great article. I was getting stuck on adjusting the mirror 2 bracket, I couldn’t move it any further to the right. I read another post about checking the tube placement. I could see the tube wasn’t aligned with the frame/gantry. I easily adjusted the laser to be straight and that put the laser in the correct range of mirror 2. Just wanted to mention this in case anyone else is chasing their tail like I was.


I did the Alignment and everything is done! But Still i hitting in the front of my laserhead. How do i get it to move to back of the nozzle. Left and right i do with the screws on the right.. But to move forward and backwards?

Last edited 15 days ago by Harold

Hello Sir,
I tried to align the mirror as I saw here.

The first problem was that from tube beam was hitting into the mirror quite low, so I raised mirror 1 about 4mm.

Then it was quite easy to align with mirror 2 but I had also to race mirror 2 now.

Then ofcourse I need to race laser head and I did but beam hits it in a corner, and also at top right corner it is few millimeters to high.

I have put laser head on I angle (raised left side) so beam hits center of lens, for engraving it works fine, but for cutting I can see its cuts on a angle.


Last edited 23 days ago by Renatas

thanks for responding 🙂

I have changed quite a lot, so I will repost the steps I took.

  1. 1 I noticed that the beam from the tube hits the first mirror quite high, so to not mess up with the tube I raised the mirror 1 about 4mm, now it’s dead center.
  2. comment imagecomment image

  1. 2 the main thing from the youtube guide was when align mirror 1 to mirror 2 first align horizontal and vertical to gantry axel witch I did. Moving mirror 2 to top and back to bottom, both test shots were dead center. And also I raised mirror 2 because I raised mirror 1.
  2. comment image

  1. 3 Then it was the turn of mirror 3. I adjusted mirror 2 so it goes parallel with the bottom x-axis and both left test shot meets right test shot dead center than I moved to the top right and top left. The top left was in the same spot as the bottom left and right, but the top right was 2 millimeters too high.
  2. comment image

    I found that I can lift the gantry top right corner with few metal washers which I did but it didn’t make any difference.
    The main problem is that beam from mirror 3 to the lens is hitting in a corner.
    This image shows the laser head raised and regular height shots of the focus lens burn from the bottom of the laser head.
    not raised laser heads lens shot look better, but mirror3 shots are too high.comment image

Last edited 21 days ago by Renatas

Hi ,

I was having a problem in my gantry that was not standing straight in the bed. Took out the gantry and fixed the problem. But know the right side of the gantry does not run smoothly. And when tensioning the left side to tide I won’t run. What is the best way to tension the Y belts


Hey there, I am having an issue aligning my laser after changing my tube. I have went through and aligned it 6 times or so I thought, First couple times I had a shadow. I reset the tube and it appeared center no more shadow. I then adjusted the other 2 mirrors assuming again it was centered on all four corners. On my laser I have a circle frame in front of mirror 1 and mirror 2 so I went off that to set this time and put the tape there? All looked good cleaned mirrors and tried again this time I can not cut through 1/8 wood at even 18 it is a 100w laser with a brand new reci 100w tube.
I am a single mom and was part of the deep freeze in Texas and both my laser tubes cracked with no power of water for days, Bought now 2 tubes first one arrived cracked. I have been down for almost a month now and am running out of ideas. Please help.


Changed my laser head holder. Have good alignment at all positions on the table. But unit will no longer cut with the power that it had prior. I was cutting 6 mm pine at 8mm jog and 18 percent power. Unit now will fail to cut 3mm into same material at given settings.
It extremely frustrating.
Any ideas


How would that happen. Bad alignment on head mirror ?


I have two issues. Beam hits center on laser head mirror. Burn is off center. Mirror was shimmed originally but I changed brackets for the head to one that wasn’t bent from the factory. If you turn the laser head mirror left or right does that effect where it will hit on the lens ? Almost changing the angle of the head mirror?

It’s brand new and I already broke it I have another one I used for like ever. And I bought this one because it was nicer.


It appears that I have gotten the laser fixed and focused. Do you have a suggestion for a new laser head. With screw adjustable head mirror that is short enough to work on the k40.

The lens ended up needing shimmed . It was shimmed when I took it apart. And I would like to be able to just turn screws to adjust it not paper shim it.

Thanks for the help btw.

Your knowledge was excellent

geoff Fischer

I tried to follow your guide but am having problems. Mirror 1 is centered, by mirror 2 I’m getting 3 small holes and by mirror 3 I’m getting nothing. Mirror issue? Laser bad? Laser is pinkish purple when firing but the power is diminishing or very poor for some reason. Only has this like 2 weeks, worked fine out of the box but now this 🙁 any help would be appreciated!

Steve Lee

Thanks for these instructions, I was chasing my tail until I found them.

I think I am close just not quite there.

Mirror 1 is in the middle, mirror 1 to mirror 2 is square, mirror 2 is is the middle.

Bottom right is correct, bottom left is correct. But top right is off, 1mm left and 1mm up. Top left is halfway between the placement of the top right and being centred.

Also, when the laser passes the lens, it also comes out to the right by 2mm (opposite side to when the beam enters).

Any advice please?


Steve Lee

Thanks for getting back to me.

Im now even closer but not there yet. I raised the back right by 1, 2 and 3 thick washers. 1 wasn’t enough, 2 brought the top left into line, but 3 made it go out again.

So with two washers, the 1st and 2nd mirrors are aligned and in the middle, bottom left is centre, bottom right is centre, top left is now centre, top right has come down to be level with centre vertically, but 1-2mm to the left.

I have attached a pic, the 3 centre dots are on the right, the off one (top right) is on the left.

Any more advice please? Thanks very much.



Firstly thank you for the guide, have used it myself multiple times, as well as advising others to check it out.

On the current machine I am working on, the everything is spot on as above, except the drift to the left when in the Back Right Corner.

I have identified the bar and coupler (original bed is stripped from this machine, but am unsure what you are referring to move etc.

Are you able to advise further?


Thanks for the great guide, I did everything as instructed but I didn’t get a good result. Namely, the laser does not cut up to the right and it cuts perfectly on other parts. I checked the mirror settings and
Bottom right: centre
Bottom left: centre
Top right: centre
Top left: up from the center by 1mm
I didn’t try to adjust the beam because I will disturb the other sides. What can I do to fix it? Thanks in advance. I Sorry for the bad English.


So I have a perfect dot on my mirrors all where stated. Mirror 3 perfect same dot in the centre

but when I move the mirror 3 to the top left or right the dot is quite off centre for both tests. Does this mean my gantry is off?


had to replace my lens. did your test i had to move my 1st mirror in so the laser tube would be center.(i believe this might be my mistake) continued to line all the other two mirrors up and finally at the head assembly my bottom left mark is dead center but when i move the head to the bottom left it goes up and becomes double

Julia Kosir

So i have all my corners alligned except for my top right. I aligned all my mirrors parallel, not to the center. I also just re aligned my bed to 0.1mm difference on all ends so it is very straight and i raised all the other 3 ends to make the top right lower (as suggested everywhere online) but it did not change where the beam was hitting. I also tried shimming 4x the distance i needed but i still did not make a difference where the beam was hitting so the shimming is clearly not the problem. I do not know what do now. If i align the top left corner and the top right corner, than the bottom left corner hits too low (essentially the same thing as above but reversed), so i am truly confused as to how to fix this problem. Any help would be extremely appreciated as this issue has made me pretty upset.

Julia Kosir

Thank you for the speedy response, it means a lot

Bottom right: centre
Bottom left: centre
Top right: below center
Top left: centre

Attached is a picture showing how the beam hit the tape on the laser head. The middle beam is darker cause all the other 3 sides of the machine hit at about the same spot, but you can see that the top right is sitting too low for some reason

Julia Kosir

Thank you very much for the assistance, I will see how well it cuts as soon as I have the time, and if it is not adequate I will try the above. One last thing. my 30mA Current Meter that came with my k40 (analog version) does not appear to work when the laser is running. I can get it to work if I tap the top but then in a few seconds it stops again. Any idea on how to fix this? I know this is not directly related to mirror alignment but someone else on here may also encounter a similar issue.

Julia Kosir

Also to note, those 4 red dots around the circle are just an indicator for me to see approximately how close I am to the centre (not actua laser burn marks) because my eyesight is a bit poor and I have trouble making out the circle else wise


This is, by far, the easiest tutorial to follow. Thank you for putting so much work into it!
I have a quick question, if you don’t mind. I’m having a hard time aligning mirrors 2 and 3. I need the beam to fire down and left more, but I can’t seem to get the top left and bottom right corners of mirror 2 close enough to the back plate because the screws come apart from the front plate. Am I missing something? Is there a way to remedy this issue? I appreciate any help yours willing to offer.


Nice guide, thanks. Even if everything in K40 regulation is pretty much evident, I am facing problem that is currently breaking my head in two.
I brought home K40 from public workshop for some laser cutting. I noticed that it does not operate at the power it should. After disassembling the head the problem was evident – third mirror (that brings the beam vertically down) and focusing lens should be better replaced.
After receiving both mirror and lens from aliexpress I assembled the head together, but now the beam does not hit anymore into the center of the bottom hole. Putting a piece of paper or two under the third mirror does not help – now the upper edge of the mirror is to be lifted about 1.5 mm to direct the beam vertically down! And such deviation is far from “fine adjustment” term.
I just totally do not know what happened. It worked fine previously. I believe I did not lost any parts nor anything seems to be missing from the assembly. Overall geometry seems to be fine for the first two mirrors, and in fact this have nothing to do with the current prob 🙁
I just can’t figure out… 🙁


Hello! Your guide is great and much appreciated. I have an issue I didn’t see in the comments and previous answers, I am sorry if I missed it. I have aligned my test fires and they line up but when test firing with the head at front right (closest to me, right side) through about halfway up towards the back right, I get no dot. As I get closer to the back right, I start to get the burn mark and at the top right it’s aligned with my back and front left dots fine. But that whole front right quadrant seems to get no power in the test fires as it won’t mark the paper on mirror 3.
I should add that if I repeatedly fire in bursts I may finally get a tiny dot which does seem in the correct place, so it doesn’t seem that the bean is out of place there just very weak
Any ideas on the cause?

Bruce Garoutte

Here is a little trick that I learned on my K40. To help ensure that the thumb screws do not move while tightening the lock nut, I use a pair of 8″ curved Hemostats to hold the thumbscrew. Now, as I tighten the locking nut, I can securely hold the thumb screw and keep it from turning. This really helps cut down on the errors incurred by trying to hold it by hand while tightening. Also, the Hemostats can get in those tight places where my fingers do not like to go.

razvan constantin

First theank you very much for this isntructions .I do all the steps but one i can not get it wright .STEP 3 dont matter what i do the beam move 2 mm up …i try to put something onder to elevate the head but still i get the twoo mm diffrence .Do you please have any ideea what can be .
Kind regards


Hello, I am having an issue aligning my mirrors. I’m stuck on the first step. After I adjust the screws on mirror one so that the laser hits the center of mirror two in the far position, I move mirror two to the near position and test the laser again. There is no change vertically, but horizontally the laser is firing several mm to the left of center. The guide says to adjust the white plate that mirror 2 sits on to correct for this. However, I can only adjust the plate 1-2mm before it is scraping against the side of the frame and prevents the gantry from moving. And, I don’t notice any difference in results when I make this minor adjustment and then start over from the beginning. Is there something else that could be causing my 2nd mirror to be in the wrong spot? And, is it normal to have so little room to work with when moving the white plate?


Thanks for the help. I ended up moving the whole gantry (and consequently mirror 2) as drilling new holes for the first mirror would have been a lot more work. When I moved the gantry as far to the right as the pre-drilled holes allowed, I was able to get everything aligned in a matter of minutes. I’m guessing it had shifted during shipping.


after did all of this and 3rd mirror is centered and i try to cut my wooden piece but unfortunately it is not like before.power is very lower and why is it?

Jacob Smelt

My laser is hitting the edge of the lens how do I fix this please

Jacob Smelt

Thanks I will try this


Thank you for the excellent guide. you made my alignment an easy task to do.


I love you man. 3 days of work and nothing. 30 minutes with your guide and everything is perfect. Thank you very much


Thank you for the mirror alignment instructions. I have my mirrors aligned, but when I start my engraving project, there is a shadow. I’ve had this problem before and fixed it, but I cannot remember how I did it. My mirrors are aligned and clean. Any suggestions?


got a question. in the beginning of the guide it says if the test fire it to low or too high at the second mirror, then the bracket for mirror 2 maybe to low or too high. what about any adjustments to the screws on mirror one. do they ever come into play?
im having an issue where i cant really cut anything on the right hand side of the cutting platform. lens and mirrors are clean. i dont appear to be hitting the inside of the air assist nozzle.


Hello You say to add a shim on the mirror to raise it ?? what is a shim ? how do i do that ?

Thank You


Hi there, first let me say thanks for the articles, very helpful. I have just bought one of these machines and your alignment advice is great for me, the only thing that I am struggling with is the lens adjustment using the tool – would it be possible to add a photo to show the tool in place to help understand the usage?

I am trying to get my machine to cut MDF and acrylic, and so far test pieces show that with the 40w tube I can only cut a maximum of 1mm deep in one pass, and to get any deeper requires many (15+) passes, so am suspecting that something is up with the lens alignment. Of course, I had to follow many of your tips to get the machine to that stage! They are cheap, but you get exactly what you pay for!

Gary hunt

Amazing guide had to shim up second mirror and shim up right side of my tube now my beam on all mirrors are centred cuts like a dream!!!!!!

Ryan Pacheco

How much to have you help me align? I can’t figure it out. Mirror 2 hits center and mirror one is off to the far left and down. About to the rim of the mirror.

Wayne Erney

ha if all mirrors are in alignment but the laser beam is hitting on the inside of the air assist head what is the fix for that?


Have followed Your guide mirror 1-2 hit centre target but not dead, Moving to mirror 2 – laser head, at the bottom right target hit centre at bottom left target hit centre but not dead, moving to top right target hit up to the right. Please help with solutions.


URGENT!!!! in your mirror alignment guide you said we should place mirror 2 at the far end before setting, you now mentioned ADJUST MIRROR 1 UNTIL IT GET TO CENTRE OF MIRROR 2, my question now is, are we to adjust the mirror with the knob behind mirror 1 or adjusting the mirror itself to get the dot to the centre of mirror 2.


After the centring from the bottom left of mirror 1 to mirror 2, moving mirror 2 close to mirror 1 the DOTS are beside each other with the use of the 3 knobs behind mirror 1, in your guide you said we should loosen the mirror 2 and slightly move it to the right and start all Again.
My Question is, DO WE NEED TO UNSCREW THE 3KNOBS TO IT ORIGINAL POSITION before starting allover with the alignment and re-centring.


is there a guide pr can you tell me how to adjust my x axis belts? there are two philips that adjust tension, but i cant tell which way to adjust. im getting curved lines where there should be straight lines. Im very frustrated over something that seems so simple! Thank you


Hi, I have aligned all the mirrors, but nothing comes out of the head. I have placed a small bit of card between the 3rd mirror and the lower lens. There are burn marks on the card, a bit off center but they are there. I just don’t know what to do next. I have polished all the mirrors, turned the lens around so much I now don’t know the correct way, is it the oval face facing up or down. I thing that it must be that somehow the beam is just not hitting the lens center, but how do I adjust that.?…

Bernd Uthoff

Hej HP,
1000-Tak for dit fantastisk fine styke arbejde!, det har sparet mig for mange timers arbejde.
Har det rigtigt godt



Thank you for your work preparing this tutorial.


My 2nd mirror when its far from the first mirror its perfectly in the middle but when it gets close to the first mirror it goes to the upper right corner only for like two and a half millimeters.I wanted to ask if you can tell me a way to solve this problem.and get it perfectly in the middle in both ways.When its close and when its far.i already tried to adjust it but it didn’t work.


I’m centered on step 3 and step 4 but when I put the leaser in home position it’s high right

S.C. Haywire

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?”

Chad Shumaker

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!



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


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!


ok, i will try!!

Many, many thanks!

Larry Ross

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.


Hi Great guides! I am a little confused by the .txt intructions supplied for your aligntool download.

when you say glue the pieces together in what orientation? stacked on top of each other like playing cards? and is the tool fitted over the beam input hole going to “mirror 3” or under the lens at beam output from laser head as it exits the lens?

Maybe a few pictures added to the ultimate mirror alignment would help clarify?

Many thanks


thank you for the reply… I am setting a kh 3020 at the moment to replace my old windows XP only K40 so your guides have come in very handy. Ammeter fitting next on the agenda.


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?


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


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?


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.

Shannon Morgan

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?

Jason B

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


I’m having this exact same issues except only my front right position shoots about 8mm to the right. All other positions hit the same spot.

Hari Wiguna

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!

Joel Brondos

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.”

Joel Brondos

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?

Aaron Birenboim

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?


Thank you very much! Best guide!! The laser Bible! ?

Perry Thompson

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?

Telmo Carquejo

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 …


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..

Bob S

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!


Second time using this guide, now with new mirrors and lens I bought ages ago! Thanks Hakan!


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