LaserUser.com Forum (formerly RDWorksLab)

Thats the thing - 1-2-3 mirrors are perfectly aligned at position 3 (longest beam path, bottom right), but as soon as i drive gantry all the way up (pos4) beam walks away vertically. And pos4 is not longest distance to travel. If i align perfectly to pos4 (top right) beam walks away vertically at pos3 (bottom right). But ONLY vertically. No diagonal travel of any kind...

You have 1-2-3 tunnel vision. If the spot moves on #3 when the gantry moves in Y, then you are not quite right on #2.

Maybe, but only because i got fair understanding of how geometry works.
I will try it, but i'm pretty sure adjusting #1 to fix #3 in only one Y position will do nothing to fix the situation.

At the moment i'm thinking doing string test for parallelism of Y rails and possibly over-jacking one foot on the machine to untwist it.

So plan of action:
1. Reset the tube position to back and floor of tube compartment;
2. Reset mirror swivel plates same distance from base;
3. Remove shims from left top rail foot (will increase misalignment by quite a lot on TR);
4. Realign #1-2-3 to BR position (TR position WILL be out by 5-6mm vertically);
5. Crank up the TL corner of the machine to see if any effect on TR misalignment;
6. Mess with #1 as per suggestion;
7. If all that doesnt work, cry into pillow... as i'm out of ideas
8. Check parallelism with string test...

About right ?

I agree with Pete - get yourself a a laser level that will project a plane of laser light (it appears to be a line, but it's really a plane). Then you can use that to see if you X and Y axes are straight and planar. If they aren't, then fix them. If they are, then align the laser beam properly, as per others' suggestions.

There was a thread here where a fellow posted a few videos of how he tested the planarity of his machine using a laser level. It'll probably take some effort to find it; I'm sure it was in 2021.

Yep, i would like to see that. Help me find it.

Ignas Kaz wrote: Sat Aug 21, 2021 Yep, i would like to see that. Help me find it.

Okay: viewtopic.php?p=29667#p29667 .

-Jeff

Well, many more of ideas were tried now.

I specifically unleveled the feet of the machine until it rocked on 2 points only, no deformation in chasis whatsoever, no effect on beam alignment. Tried to "lift" the left back corner of the machine (where we shim to lessen the vertical walk) - no effect.

I've rechecked all motion components for loose parts, nothing rattles, nothing's loose... Gantry, idlers, rails, gantry-to-rail blocks, etc...

Then, as per many, many, MANY suggestions i straightened the tube to within a millimeter of the tube compartment (51mm from bottom, 19mm from the back wall), then strike mirror1 and go from there... No effect to the problem.

Then we received a video-call from an American Photonics gentleman, who, after receiving all the information confirmed that the machine is twisted. I also was assured that, really, the positioning of the tube doesn't really matter (as i suspected all along, unpopular opinion ) as long as 1st mirror is struck in the center properly. With this in mind he gave me an idea on how to raise the beam without raising the tube higher than the mounts will go. It made a bit more difficult to steer the beam in diagonals, but it is fairly simple, if tricky. None of this helped to alleviate the problem.

In the end i put the machine with ~2mm vertical misalignment back as good as i could with 4mm shimming on TL rail, aligned perfectly at middle of right rail (instead of bottom right as i usually do) to spread the error a bit better throughout Y and left it there.

Now, ALL of the attempts to align the machine ended with the same and CONSISTENT result - TL perfect, BL perfect, BR perfect, TR high. Tube nice, tube crooked, unshimmed (error ~6+mm), all the same result - TR high.

This is proper tube aligned and 1st mirror strike:
Then there's this - mirror1 holder plate (not the holder itself) mounted off 45deg at the factory. QC my butt, someone just eyed the installation of that. I corrected it before starting the tube position experiments:
I was thinking of getting the reverse alignment tool from American photonics, but upon thinking on it all it would do in this situation is prove decisively that there is twist in Y, but show up on the left side (instead of right).

At the moment i'm at a complete loss here...

Dave- Russ has a new Vid posted on the 4th corner problem. I an still struggling with this on the 1800x1300 laser [ along with the beam spread [cannot think of the term right now- it usually comes to me in an hour or so- divergence maybe?]]. I may give this one more shot- then I am going to stick to my 6 yearold 1300x900 with the original EFR tube still working well. I am too near the end to devote years to something I don't really need.

Gene Uselman wrote: Tue Sep 06, 2022 Dave- Russ has a new Vid posted on the 4th corner problem. I an still struggling with this on the 1800x1300 laser [ along with the beam spread [cannot think of the term right now- it usually comes to me in an hour or so- divergence maybe?]]. I may give this one more shot- then I am going to stick to my 6 yearold 1300x900 with the original EFR tube still working well. I am too near the end to devote years to something I don't really need.

Russ Video adjusting mirror 4 https://www.youtube.com/watch?v=nY6czB6ygFM
Cliff notes to Russ's video - position 4 is tied t the alignment of Mirror 1

Recommended action: perform a normal alignment of alignment of 1,2, and 3
then work on alignment of 4 by adjusting Mirror 1 (iterative process)
then work on alignment of 3 by adjusting Mirror 2 (iterative process)

I actually started doing that this AM and was so tired that I burned a nice mark in one fingertip. I have not burned myself in the last 5 years...
I have severe sleep apnea and am tired all the time, I decided that my brain was not functioning well enough to be at work and went home.