need desperate help aligning gweike laser engraver/cutter

[tadici mihai]

Hello everyone...

I got a new laser, LC1290 from Gweike with 100w RECI, and i had to dismantle the top parts, not the rails, to be able to get the monster in the office.
now i have a biiiig problem aligning the beam.
so, i'm coming with some questions and begging for some experts help and reply's
1. at a table of 1200x900, the beam can be set to hit the same place, on all the table surface, or it's just a myth? I can make the beam hit left up, left down and right upper corners on the same place, but, as I go to the 4th corner, down right, the beam is going on a down path.
if I get the beam to be on the same point on left up, left down, and right down, I will get the beam too high in the right upper corner, on the moving head...
what I am doing wrong?
2. is a must to center the beam on all 3 mirrors?
3. how can i check if all mirrors are on the same level?
4. is anyone have a tutorial to allign the mirrors from the point of mounting, not just fine details?

please help me!
thanks for reading and for possible answers

[Michael Reilly]

You should be able to get it very close, but perfect is probably not practical.

I don't have that laser, but typically you have a set of alignment guides that fit into holes in front of each mirror. They may have a metal + shape that you can slip paper behind so when you fire the beam, you can see where it falls relative to those marks. A trick I learned is that you can use labels from thermal label makers which are highly sensitive so you can run at low power and get very sharp marks. If you have a laser pointer you can rely on that as long as you confirm that when you fire the beam at a piece of paper, the mark is in the same place as the red dot. If it isn't, you need to adjust the laser pointer first.

The process is to use a target to center the beam at the first mirror, then center it to the next mirror, and so on. This is very rough alignment.

Then, assuming your laser points to the left, you move head to top-left and using the first adjustable mirror after the laser, get beam centered at the target before the mirror on the gantry. Then move the head to bottom-left. Use the second adjustable mirror to adjust until beam is centered there. Move back to top left and use first mirror to re-adjust. Go back and forth many times as it gets closer and closer with each pass.

Once it's reasonably close, then you can use the third mirror on the gantry arm to adjust the beam going across the table, to center on the mirror just before it goes down through the lens. Keep the arm at the top of the table and move the head left to right.

If your last mirror is adjustable, then you adjust until the beam is centered in the nozzle if you have a nozzle.

If your system is mechanically true, then the bottom-right corner should be in alignment when the other three corners are good.

Especially when things are way out of alignment, it can take an hour or more to get it back in shape. But from there it should be a tweak here and there. Keep in mind if you remove a mirror to clean or replace it, you'll have to re-align. Even if it goes back in the holder without touching the alignment screws, it can be off enough to make a difference.

[Dave Sheldrake]

http://www.rabbitlaserusa.com/Manuals/BeamAlignment_FlyingOptics.pdf

By Ray Scott of Rabbit Laser USA

(I have no connection with Rabbit other than having purchased parts from them and being VERY impressed with Rays assistance and knowledge)

cheers

Dave

[tadici mihai]

thx a lot for info...
that's exactly what i'm doing for the last 16 days... i think there is something wrong with my laser, becouse i simply can't make it hit the mark in the last corner... it's like my beam is going down after i go far from margins... if i rise the second mirror to hit the last burn, if i go in other corner from the 4th, the beam will be be higher than the last time... i think i'm going to sell it, becouse i'm really pissed off. the problem is i can't find someone in romania who can calibrate this machine (i've knew that when i've bought it, but didn't thought it will be imposible to do it...)

[Jerome Stanek]

I had that problem and it was my tube was on an angle had to adjust all the mirrors to the same height and level the tube now it hits the same spot at each corner.

[Rich Harman]

I had that problem and it was my tube was on an angle had to adjust all the mirrors to the same height and level the tube now it hits the same spot at each corner.

Tube being level is irrelevant. My tube is purposefully at an angle to better evacuate air bubbles (as recommended by the manufacturer). Height of the tube is critical, it determines the height of all the mirrors.

[Pete James]

This could be as simple as your table not being level. Have you carefully measured the distance from the lens or lens mount on the gantry to the table at all four corner points and seeing if they are equal?

[tadici mihai]

ok... problem almost solved
i have the beam on the same place, with little error... and it's in the middle of the 3rd mirror... but my beam is coming with a little angle that i can't fix with the screws from the 3rd mirror

[Rich Harman]

ok... problem almost solved
i have the beam on the same place, with little error... and it's in the middle of the 3rd mirror... but my beam is coming with a little angle that i can't fix with the screws from the 3rd mirror

It is possible, even probable that your laser head, the assembly that holds the third mirror and your lens, is not exactly perpendicular to the table. Mine wasn't.

[tadici mihai]

It is possible, even probable that your laser head, the assembly that holds the third mirror and your lens, is not exactly perpendicular to the table. Mine wasn't.

Rich, if that is true, how can it be fixed?
one more thing... today i saw my machine is a little up on the back side, and lower on the front side... could that be a reason for my beam to be on a angle?

[Rich Harman]

Rich, if that is true, how can it be fixed?
one more thing... today i saw my machine is a little up on the back side, and lower on the front side... could that be a reason for my beam to be on a angle?

I don't know how GWeike mounts their laser heads. On mine I was able to loosen a couple screws, move and retighten for the fore/aft alignment. For the left/right alignment I had to use a more primitive method - I simply forced it into position, bending the mounting. To check that it was perpendicular I used a large carpenter's square.

One side of the machine being higher won't affect alignment. However, if one corner is taking more weight than the others it may be introducing some twist to your machine and that will make a perfect alignment impossible.

I also had to shim up the back end of my left Y axis rail in order to get it as perfectly straight as possible.

My machine did work right "out of the box", but there were a lot of things that needed to be improved. I think they quit tuning the machine the moment it works.