Serious alignment issues, twist in Y ?

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Ignas Kaz
Posts: 45
Joined: Wed Jun 19, 2019 5:39 am
Location: Coalisland
Country: United Kingdom
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Home Position: TR
RDWorks Version: v8.01.18
Windows Version: 10

Re: Serious alignment issues, twist in Y ?

Post by Ignas Kaz »

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...
Dave Vigness
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Re: Serious alignment issues, twist in Y ?

Post by Dave Vigness »

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.
Ignas Kaz
Posts: 45
Joined: Wed Jun 19, 2019 5:39 am
Location: Coalisland
Country: United Kingdom
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Laser Machine Make or Type: Chinese 9060
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Home Position: TR
RDWorks Version: v8.01.18
Windows Version: 10

Re: Serious alignment issues, twist in Y ?

Post by Ignas Kaz »

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 ?
Jeffrey Aley
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Fire extinguisher (for big fires)
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Re: Serious alignment issues, twist in Y ?

Post by Jeffrey Aley »

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.
Ignas Kaz
Posts: 45
Joined: Wed Jun 19, 2019 5:39 am
Location: Coalisland
Country: United Kingdom
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Home Position: TR
RDWorks Version: v8.01.18
Windows Version: 10

Re: Serious alignment issues, twist in Y ?

Post by Ignas Kaz »

Yep, i would like to see that. Help me find it.
Jeffrey Aley
Posts: 387
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Location: Folsom, California
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RDWorks Version: 8.01.24
Ruida Controller: RDC6442
Accessories: Spray bottle with water (for small fires)
Fire extinguisher (for big fires)
Windows Version: Win10 Enterprise

Re: Serious alignment issues, twist in Y ?

Post by Jeffrey Aley »

Ignas Kaz wrote: Sat Aug 21, 2021 12:45 pm Yep, i would like to see that. Help me find it.
Okay: viewtopic.php?p=29667#p29667 .

-Jeff
Ignas Kaz
Posts: 45
Joined: Wed Jun 19, 2019 5:39 am
Location: Coalisland
Country: United Kingdom
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Laser Machine Make or Type: Chinese 9060
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Laser Bed Size: 9060
Home Position: TR
RDWorks Version: v8.01.18
Windows Version: 10

Re: Serious alignment issues, twist in Y ?

Post by Ignas Kaz »

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 :D ) 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:
20210823_120733.jpg
20210823_120449.jpg
20210823_120438.jpg
20210823_115441.jpg
20210823_115427.jpg
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:
20210823_133741.jpg
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...
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Gene Uselman
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Re: Serious alignment issues, twist in Y ?

Post by Gene Uselman »

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.
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Pete Cyr
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Re: Serious alignment issues, twist in Y ?

Post by Pete Cyr »

Gene Uselman wrote: Tue Sep 06, 2022 8:53 am 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)
Location - VA
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Gene Uselman
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Re: Serious alignment issues, twist in Y ?

Post by Gene Uselman »

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.
If the Help and advice you received here was of VALUE...
Please consider making a donation to maintain the RDWORKSLAB Forum.

BT48 Alpha Shopbot and 1300x1800 130W Laser

The days that I keep my gratitude higher than
my expectations, Well, I have really good days.

Ray Wylie Hubbard
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