Need Help!- newbie needs help with laser alignment

[dominic gailgan]

Hi I have a k40 chinese laser engraver and I have been trying to align the beam as I got new reflective mirrors. I can't figure out how to align the second mirror. When it's closets to the tube I set the beam to the centre of the mirror but when I move it far away the beam is now off the mirror bracket to the left. If I set the beam here and move it faward the beam is no longer in the middle. How do I align the mirrors? Any help please.
Thanks Dom

[herby08]

Hi dominic
first prepaire you for a while of twiking.
what you have to do is like my system: i cut out of 1/8 pressboard squares in the size of the outside of the holder ring, then I put two stripes of tape on the piece and stick the hole thing on the holder ring and tape to the back, ( this prevents the mirror from damage because I dont remove the mirror)
the first wher you do this is the mirror right next to the laser tube and shoot a beam the brown point should be around the middle of this mirror .I marke the middle of the press board with a compass.
then you go on the Y axis and put the press board on this holder ring and move them to the back ( closest to the tube ) and shoot a beam put the settings on about 6 to 8 % shoot just as much that you can see the brown spot it shoud be somewhere around the middle and marke it
then you slide this mirror ( gantry mirror) to the front of the machine
( the farest from the laser tube) and shoot another beam see where it lands
now comes the tricky part you have to adjust the 1st mirror closest to the laser tube to get right on the on the first ( marked spot)
now go back and forth and see if the spots are allway on top of each other.
this way you have alligned the Y axis and take the pressboard off
now you take a piece of tape and put it right on top of the laser head opening move the Y axis to the back and shoot a beam and see where it lands if you dont see any brown spot take a 2inch stripe about 5inch long and hold it just in front of this openeing and shoot a beam maybe shoot a second time this way you see where it lands now come the fiddleling what could take a long time.
to adjust the laser head mirror you have to use the set screws on the second mirror ( gantry mirror) but be carefull dont turn to much just play a bit to see how it works the brown spot should be here around the middle of the openeing on the laserhead, marke it
then move the Y axis to the front of the machine and shoot another beam.
if you are lucky it the two spots are exactly on top of each other if not you have to use the gantry mirror setsrews to bring the second spot right on top of the first one
after they are right on top of each other ( just be paitient) then move the laserhead to the right rear corner and shoot a beam again this should be exactly on top of the other two if not you have to use the gantrymirror setsrews again bit just very little ( on some machines a turn of 1/16 is allredy to much)
now you have to go back after adjusting this spot to the first position left rear and check the spot if it is still there
after all this matches you have to go to the front right corner and try the spot there and do the same like on the other spots .
like I said be patient you will get it right.
my first time took me 4 hours. but now I do it in 20 min.
I hope this helps
greetings
walt

Originally Posted by dominic gailgan Hi I have a k40 chinese laser engraver and I have been trying to align the beam as I got new reflective mirrors. I can't figure out how to align the second mirror. When it's closets to the tube I set the beam to the centre of the mirror but when I move it far away the beam is now off the mirror bracket to the left. If I set the beam here and move it faward the beam is no longer in the middle. How do I align the mirrors? Any help please. Thanks Dom

[Exsecratio]

Hiya Dom,

If the beam is striking mirror one in the centre then mirror two in the centre but off centre as mirror two moves away then the tube isn't aligned.

To get spot on alignment the tube has to be @ 45 degrees to mirror one when the mirror is @ 45 degrees to the slideways.

Basically you are looking to have the tube at the same level and paralel to the cross slide (the left to right slide) to get perfect alignment.

The machine will work and will cut over the entire table if the tube is out but you will always be chasing your tail.

get the tube correct then alignment becomes so much easier in future.

best wishes

Dave

[dominic gailgan]

How do I align the tube? I can't see any way of moving the tube. The beam does move off centre as it moves away. But how to fix this I'm not sure of. Help please.

Thanks Dom

[Exsecratio]

Hiya Dom,

I'll write it up in detail with pics in the morning for you

best wishes

Dave

[dominic gailgan]

Any help will be good. Just had another look at this. I can set the first 2 mirrors but when I go to set the laser head I have a 40mm difference between the closest and the far away movement. I don't understand how to set set the beam in the same spot at all y axis extremes. It's not the mirrors, just put new ones in. I'm beginning to wander if this machine is fatally flawed as so many people complain about the poor build quality of the machine. And as there's no manufacturer's name on it I can't ask any body for technical support.

[dominic gailgan]

I have just noticed that the second mirror and the laser head are not in the same line. The head is 7mm closer to the tube than the mirror? Is that a problem? There's no more adjustment in the laser head. And there's no front back adjustment in the mirror bracket. Can I use a visible laser light to set the beam? If so how do I use it?

Thanks Dom

[Exsecratio]

Yup thats a big problem Dom, it means you will have to move the tube, could you take a picture of the tube clamps and their bases as the entire clamp is going to have to be moved.

I've been writing up some stuff on this today but I am concerned that over movement of the tube could result in the beam going just about anywhere and the last thing I would want is for somebody to end up blinded by instructions I post.

Most of all you will need eye protection suited to the 1064nm wavelength of the laser you have. This is one case where shortcuts can proove very nasty.

best wishes

Dave

[herby08]

Hi dom
what di you mean by 7mm closer to the tube as the second mirror?
if you have adjusted the second mirror in the way that the beam is the same place in the front and the back of the Y axis thats ok
then in order to make sure that the laser head is in the same line as the second mirror ( that the beam is exactly in the mittle of the laser head mirror opening) you should take out the mirror from the head put a 10mm round with a perfect tip thru it and measure the distance from this toward the gantry it must be exactly paralell and the tip of the round needs to be in the center of the second mirror.
if the round shows that is not paralell then you need to losen the head holder ( pair of chanel plier to unscrew) and twist them that its perfect paralell, if the round tip is out of the center of mirror 2 then loosen the 3 screws on the head carrier plate and adjust it towards toe front or rear .
only then if this is is still out of any of the critical points then you have to move the tube , but in most of the cases what I had this was all what needed to be done
greeitngs
walt

Originally Posted by dominic gailgan I have just noticed that the second mirror and the laser head are not in the same line. The head is 7mm closer to the tube than the mirror? Is that a problem? There's no more adjustment in the laser head. And there's no front back adjustment in the mirror bracket. Can I use a visible laser light to set the beam? If so how do I use it? Thanks Dom

[dominic gailgan]

Thanks for the replys. Look at the photos. The one shows what I'm talking about the mirror and head not being lined up.

[herby08]

Hi dave
I have to disagree with some :
first it is right that the beam needs to be exactly in the center of mirror one
but then the beam on mirror two would be adjusted with the setscrews of mirror one in direction gantry rear and front head on the left side.
then the head would be adjusted with the setscrews on mirror two the gantry to rear and front head to the left side then gantry to the front and rear and head on the right this takes a while like described before.
thats the way how the industrie adjust the beam .
the tube only needs to be moved when:
the hight of the beam is completly of center on mirror one
thats the best way to adjust the beam
greetings
walt

Originally Posted by Exsecratio Hiya Dom, If the beam is striking mirror one in the centre then mirror two in the centre but off centre as mirror two moves away then the tube isn't aligned. To get spot on alignment the tube has to be @ 45 degrees to mirror one when the mirror is @ 45 degrees to the slideways. Basically you are looking to have the tube at the same level and paralel to the cross slide (the left to right slide) to get perfect alignment. The machine will work and will cut over the entire table if the tube is out but you will always be chasing your tail. get the tube correct then alignment becomes so much easier in future. best wishes Dave

[herby08]

hi my friend
you can not measure this way you have to put a 10mm rod in the opening of the leaser head and then see if the tip is center with mirror two the mirror surface is what counts not the holder.
the beam burn what you show is pretty much perfect now it only needs to be the same point if you move the laser head to the rear then front then right front - then right rear if the brun mark is every where the same you got it if not you need to adjust with the set screw on mirror two it takes a bit of fine feeling especially with the right side a 1/8 turn could be already to much
with the settings make a test engraving ( a picture or so)
and post it
then we can see how it works

greetings
walt

Originally Posted by dominic gailgan Thanks for the replys. Look at the photos. The one shows what I'm talking about the mirror and head not being lined up.