Adjusting laser's light way

[notexpert]

I have some problems to adjust my laser's light way. I've tryed to focus the beam as middle of the mirrors as possible. Still, when engraving for example
some bigger photo on plywood, the results of engraving might change very much > from start everything goes nicely but in the middle of the photo it
might go very uneven and in the end the beam seems to be so strong that
it burns the picture very badly. My own opinion is that the position of the
side rails are not equal...! Have anybody had samekind problems than mine ?
I've tryed to figure this problem in my head () and I thing that once you
have adjusted those mirrors to the right position, the beam should hit always
in the same place if the rails are exactly in the same direction !
My laser is chinese made and otherwise it works very nicely ( when working
on smaller areas ). For some reason I can't reach my dealer from US, so I hope that here is somebody who could give me some advices !

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[dvdlock]

Hi and welcome to the forum.

Most of the Chinese made machines are very similar to each other but some are quite different.Can you tell us which machine you have. Then someone who is familiar with this machine may be able to advise you.

It could be something to do with the side rails but it's more likely to be badly adjusted table height. If your beam becomes out of focus because of the workpiece being too high or two low, you will get some burning and loss of detail because the spot size changes.

However, it wouldn't hurt to check y-axis I-beam alignment.

My machine is a LaserScript which is the same as a Rabbit Laser by HX Laser. I have a belt each side of the y-axis driven by a shaft along the back of the machine. The same principle will apply on any of these machines. Turn the power off and unplug the stepper motor for that axis from the control board. Push the y-axis beam to the back of the machine as far as it will go. Now at each end of the beam measure the gap between the beam and the shaft. Make sure you do this next to the shaft bearing block. It should be the same measurement each side. If it's not, loosen off one of the belt tensioners until the belt is slack. Hole the belt off the toothed pulley and adjust the position of the beam. Lay the belt back on the pulley and re-tension.
Pull the y-axis beam all the way to the front and then to the back again. Take your measurement again. It should now be parallel. Replace the motor plug and you should be good to go.

You will also need to check your table height to ensure it is level to your laser head. Un-plug both x and y axis motors. Push you laser head to one corner of the table. Use your focusing gauge and set the height. Now push the head to the opposite side, measure with the gauge. It should be exactly the same. Repeat on all corners. If these are no all exactly the same you will need to adjust your table.

Hope this helps.

Dave.

[notexpert]

Hi Dave,

Thank you for your advices and I'm sorry about my delayed answer!
My laser machine is Rabbit Laser HX 4060-SE, 60W

I did all of those measurements as you adviced and I found all of those measures quite similar. After that I measured the distance between the rails and I noticed that the measure in the end of the rails was 0,65mm wider than the front of the rails. So my first thought was that I've found the reason () and I started to do remounting for those. After mounting I measured it again and now those rails was equal from front to the end. I started to refocus the light way and as you can guess... no change - I couldn't adjust the light way to the middle of the mirror's so that it keeps the position around the table. Now I was quite helpless what to do. After a little moment of thinking I desided to unscrew those prisms from the aluminium holders and check them. I noticed that the prisms was under a lateral force which was twisting the prisms out of the aluminium holder. The reason for this seems to be the adjusting of the linear bearings on the laser beam. This
was the next step I started to check out but I couldn't get it done because
the "mighty forces" commanded me out of my study !

I'll let you know if this was the reason ( as I hope and assume ) after I've
got the permission to continue my research ! As my nickname tell's, I'm not
any expert with the laser machine, so I have to ask about the light way;
If the beam of light doesn't go exactly through the middle of the lense, how
much it will take off the laser power ?

Also, I'm very sorry about my bad English - hope you'll understand !

Best regards from Finland
- Hannu

[dvdlock]

Hi Dave,

Thank you for your advices and I'm sorry about my delayed answer!
My laser machine is Rabbit Laser HX 4060-SE, 60W

I did all of those measurements as you adviced and I found all of those measures quite similar. After that I measured the distance between the rails and I noticed that the measure in the end of the rails was 0,65mm wider than the front of the rails. So my first thought was that I've found the reason () and I started to do remounting for those. After mounting I measured it again and now those rails was equal from front to the end. I started to refocus the light way and as you can guess... no change - I couldn't adjust the light way to the middle of the mirror's so that it keeps the position around the table. Now I was quite helpless what to do. After a little moment of thinking I desided to unscrew those prisms from the aluminium holders and check them. I noticed that the prisms was under a lateral force which was twisting the prisms out of the aluminium holder. The reason for this seems to be the adjusting of the linear bearings on the laser beam. This
was the next step I started to check out but I couldn't get it done because
the "mighty forces" commanded me out of my study !

I'll let you know if this was the reason ( as I hope and assume ) after I've
got the permission to continue my research ! As my nickname tell's, I'm not
any expert with the laser machine, so I have to ask about the light way;
If the beam of light doesn't go exactly through the middle of the lense, how
much it will take off the laser power ?

Also, I'm very sorry about my bad English - hope you'll understand !

Best regards from Finland
- Hannu

Hi Hannu,

Don't worry about your English, it's a million times better than my Finish

I'm pleased to hear you got your rail alignment set. up.

It is important to get your mirror alignment as accurate as possible. The hole that the beam enters in the laser head is not very big. You need to have that beam entering hole dead centre. If you can achieve this the beam will be hitting the final mirror in the middle and you will achieve optimum focus at the focussing lens.

You should have received some dvd's with your machine. One of these has a video of the mirror alignment and is well worth watching. If you didn't get it you can download it from here http://www.hxlaser.com/support/home.htm

Good luck

Dave

[notexpert]

Hi Dave,

After two weeks serious work of adjusting laser prisms, I've finally reached a point where I've got the spot centered almost middle of the mirror. It has been a long way to do with several different measure equipments, but I'm quite happy with the result - I'm not anymore sure is it even possible to adjust the spot 100% middle, but I'll try to find out. The results of cutting and engraving are totally better than 2 weeks ago ! Thank's to you for your advices and kind
help with my problems and I'll let you know, if I'll reach the "absolute" point of
centering > Now I can start to utilize the famous Finnish wood !

Best regards
Hannu