Serious alignment issues, twist in Y ?

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Ignas Kaz
Posts: 45
Joined: Wed Jun 19, 2019
Location: Coalisland
Country: United Kingdom
Nickname: baronpork
Laser Machine Make or Type: Chinese 9060
Laser Power: 80w
Laser Bed Size: 9060
Home Position: TR
RDWorks Version: v8.01.18
Windows Version: 10

I need a validation or rejection of my theory that this machine has a twist in Y, non-parallel rails.

Trying to sort out a 900x600 80w rdc6445 machine. Spent 2 full days trying to align and shim it with no success. I've done quite a few of lasers, but this one throws me for a loop.

Location index looking from the front of the machine, beam comes in from top left:
1 - top left
2 - bottom left
3 - bottom right
4 - top right

The person who got this machine explained to me that doing usual alignment he's getting beam travel between location 3 and 4, while 1-2 and 2-3 are perfectly centered and spot on. For me its a clear sign of twist in Y, non-parallel rails.

So i went to see myself. I, foolishly, assumed tube set from factory would be more or less ok (on that later).
Upon trying to align it I, as well, would get perfect alignment in 1-2-3 locations, but 4 would always strike high, by quite a lot (~5-6mm). And no matter mirror twisting i couldn't get it out.
So i resorted to shimming. Tried all 4 rail mount locations, but the only location that made any difference was top of the left rail (position 1). So i started shimming it up by sticking ~1mm thick shims under the mount foot. By sticking 4 shims i reduced travel between pos3-4 by half (to about 3mm). At this point the work day was at an end, so i made machine workable, tightened down and left it as is.

Second try involved me completely rechecking all beam components (bar mirror1). What i discovered was that tube mounts were wayyyyy off parallel to the machine in both vertical and horizontal positions, by significant margin. So i re-spaced tube to strike center of mirror 1 and tried realigning again (after removing all the shimming, to put machine the way it came from factory). Exactly the same thing happened - pos1-2-3 perfect, 3-4 walk away by ~5-6mm. So i shimmed it again to make the machine somewhat workable again (walk of ~2mm), as it was close time...again... The only thing i never moved was mirror1, its still as it was set in the factory.

By my estimation i would need to shim 8mm (total, +-), but i cant do that for tube mounts don't go high enough and i can't adjust mirror2 and 3-head vertically. So now i'm just scratching my head and trying to figure out what next steps i should take.

Machine is sitting on concrete floor, feet had been leveled.

All of this is pointing at machine being twisted, or rails not parallel. I need someone else to either confirm or deny my thinking. With constructive criticism...

HELP :D

Some pics:
20210817_191851.jpg
As the machine sits now, with 4 shims in...
20210817_165939.jpg
The gradual shimming test result, gap gets smaller more shims i add, all the shot columns are of pos3-4, then tape moved over, shimmed up and nex test.

Next pictures illustrate how badly tube mounts were set. Note screws in the foot and gap between base and vertical adjustment difference. Effectively tube was sitting looking up and towards mirror1 (looking from back of the machine).
20210817_100228.jpg
20210817_100221.jpg
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Gene Uselman
Posts: 2180
Joined: Thu Jul 07, 2016
Location: Suburban Minneapolis, Minnesota, US
Country: USA
Nickname: Gene
Laser Machine Make or Type: QC
Laser Power: 130W
Laser Bed Size: 900x1300
Home Position: TR
Control Software: LIGHTBURN
RDWorks Version: RDw .19 & Lightburn
LightBurn Version: Latest
Ruida Controller: RDC6442
Windows Version: Win 10 Pro
Accessories: I have a combining lenses, pin tables [homebuilt], honeycomb tables , wireless remote, Modifed Ultimate Air Assist, home built non-powered rotary device, PrusaMK4 and Mini Prusa printers.

It is early and my mind is fogged but I think I have a similar problem [still to be fixed] on my new 1800x1300 machine. Russ had a video that I think may be relevant - I just tried to look it up but Youtube has done another revision and I can't find my subscriptions. It was a month ago and called something like the fourth corner... something. He claimed he fixed it by slightly adjusting the #1 mirror- altho that has not worked for me [yet]. I got so sick of chasing the problem that I took a couple months off and have just been using it- it works... imperfect but it works. Good luck
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Dave Vigness
Posts: 526
Joined: Sun Dec 15, 2019
Location: Kansas City - Rural
Country: USA
Nickname: Dave
Laser Machine Make or Type: Chine Red and Black
Laser Power: EF RF2 80W
Laser Bed Size: 20 x 26
Home Position: TR
Control Software: RDWORKS
RDWorks Version: 8.01.54
Ruida Controller: RDC6445
Windows Version: 7
Accessories: Power Switch for air assist / exhaust blower, Ma meter with switch for external digital, dual digital temp gauge, LED lights under gantry and and and.

Pics and a list here. https://drive.google.com/drive/folders/ ... sp=sharing

As long as the laser hits the #1 mirror near center, the 'position' of the laser tube to the #1 is irrelevant. The #1 is your first stable point to align from. Doesn't matter if the laser is left, right, up, down, or any other angle to the #1. The #1 takes what it gets from the laser tube and then YOU align it to the path you want.

After a LOT of trial and error, I discovered a neat way to make sure your #1 to #2 is spot on... don't put the target on the #2 mirror. Put the target on the #3 and put the head at the furthest travel from #2. That extra distance acts like an amplifier for both showing and correcting the error. You still run up and down the Y axis and adjust #1 accordingly, but when the dot on the #3 no longer moves when you move the gantry in Y you have it dead on. I fought about a 3mm jump in X for over a year and lived with it until somebody passed this trick on to me.

After that, aligning X is a breeze.

Hope this helps.
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Gene Uselman
Posts: 2180
Joined: Thu Jul 07, 2016
Location: Suburban Minneapolis, Minnesota, US
Country: USA
Nickname: Gene
Laser Machine Make or Type: QC
Laser Power: 130W
Laser Bed Size: 900x1300
Home Position: TR
Control Software: LIGHTBURN
RDWorks Version: RDw .19 & Lightburn
LightBurn Version: Latest
Ruida Controller: RDC6442
Windows Version: Win 10 Pro
Accessories: I have a combining lenses, pin tables [homebuilt], honeycomb tables , wireless remote, Modifed Ultimate Air Assist, home built non-powered rotary device, PrusaMK4 and Mini Prusa printers.

Dave- that is what I always thought about Mirror #1 too- I did not have any luck with making this adjustment as Russ suggested, but his brain is much sharper than mine apparently. I will try your alignment trick as soon as I stop having so much fun using the laser and need to punish myself further with the alignment. Thanks Gene
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The days that I keep my gratitude higher than
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Ray Wylie Hubbard- unfortunately deceased
Ignas Kaz
Posts: 45
Joined: Wed Jun 19, 2019
Location: Coalisland
Country: United Kingdom
Nickname: baronpork
Laser Machine Make or Type: Chinese 9060
Laser Power: 80w
Laser Bed Size: 9060
Home Position: TR
RDWorks Version: v8.01.18
Windows Version: 10

That's the thing, i can get pos1-2-3 absolutely spot on (longest beam path), but never pos1-4 (top left and right), it walks away by ~6mm (~2-3mm with 4mm shim). No amount of watching videos, reading articles or scratching my head works.
Ignas Kaz
Posts: 45
Joined: Wed Jun 19, 2019
Location: Coalisland
Country: United Kingdom
Nickname: baronpork
Laser Machine Make or Type: Chinese 9060
Laser Power: 80w
Laser Bed Size: 9060
Home Position: TR
RDWorks Version: v8.01.18
Windows Version: 10

... also i watched that video about "fourth corner" and its not that. beam is not walking away at adiagonal, its straight up on vertical axis.
Dave Vigness
Posts: 526
Joined: Sun Dec 15, 2019
Location: Kansas City - Rural
Country: USA
Nickname: Dave
Laser Machine Make or Type: Chine Red and Black
Laser Power: EF RF2 80W
Laser Bed Size: 20 x 26
Home Position: TR
Control Software: RDWORKS
RDWorks Version: 8.01.54
Ruida Controller: RDC6445
Windows Version: 7
Accessories: Power Switch for air assist / exhaust blower, Ma meter with switch for external digital, dual digital temp gauge, LED lights under gantry and and and.

Pics and a list here. https://drive.google.com/drive/folders/ ... sp=sharing

Okay, let me try this another way.

With the head the furthest away from the gantry, AND THE TARGET ON THE HEAD.

If you get movement as the gantry comes forward, adjust your #1 and see what happens.

If it is strictly rise / fall, that's simple. If it's left / right, the corrections are reversed as the beam turns at the #2 mirror.

I fought this nearly identical thing for over a year, not realizing how a minor error between #1 and #2 was amplified across the gantry to #3. It appears as a head scratcher, until you realize that for as much as you think you have the #1 to#2 dialed in, you are out just enough to think you are crazy. And the wider the bed, the more the amplification. I chuckle at guys that are 'experts' using a K40, and think their new pretty 5070 is cursed.

It wouldn't seem like it should make much difference, but boy does it. You may not even be able to see the difference visually on the #2 target, that's why the 'amplification' going across to #3 is critical.
Pete Cyr
Posts: 1964
Joined: Sun Nov 27, 2016
Location: Suffolk Virginia
Country: United States
Laser Machine Make or Type: Boss 1630
Laser Power: 100w
Laser Bed Size: 16"x30"
Home Position: TR
Control Software: RDWORKS
RDWorks Version: v8.01.18
Ruida Controller: RDC6442
Windows Version: Win 10
Accessories: roller rotary attachment

https://www.amazon.com/Self-Leveling-La ... 208&sr=1-7

On big machine I would recommend a laser level to get everything roughly in the same plane - it beat the heck out of the burn move burn move burn move technique when things are grossly out of alignment. (and they are relatively inexpensive and had other uses.) I did not check availability in the UK via amazon but you can I am sure.
Location - VA
Equipment - Boss Laser 1630
Power - 100W
Laser Bed Size - 16" x 30"
Home Position - TR
Full RDWorks Version - v8.01.18
First name - Pete
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Gene Uselman
Posts: 2180
Joined: Thu Jul 07, 2016
Location: Suburban Minneapolis, Minnesota, US
Country: USA
Nickname: Gene
Laser Machine Make or Type: QC
Laser Power: 130W
Laser Bed Size: 900x1300
Home Position: TR
Control Software: LIGHTBURN
RDWorks Version: RDw .19 & Lightburn
LightBurn Version: Latest
Ruida Controller: RDC6442
Windows Version: Win 10 Pro
Accessories: I have a combining lenses, pin tables [homebuilt], honeycomb tables , wireless remote, Modifed Ultimate Air Assist, home built non-powered rotary device, PrusaMK4 and Mini Prusa printers.

Dave, I think you may be onto the solution- I have been mulling this in what remains of my mind since I read it, so I tried it quickly this morning and I think it may be the answer. I am a couple months from moving the machine to the next building [renter is moving out and the sign company is expanding] so I am not tough enough to suffer thru this twice so I am returning to my main pursuit of having fun till then. If it works as it appears I will pass it on to Russ to see what he thinks- crediting you of course. Gene
If the Help and advice you received here was of VALUE...
Please consider making a donation to maintain the RDWORKSLAB Forum.



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

Ray Wylie Hubbard- unfortunately deceased
Dave Vigness
Posts: 526
Joined: Sun Dec 15, 2019
Location: Kansas City - Rural
Country: USA
Nickname: Dave
Laser Machine Make or Type: Chine Red and Black
Laser Power: EF RF2 80W
Laser Bed Size: 20 x 26
Home Position: TR
Control Software: RDWORKS
RDWorks Version: 8.01.54
Ruida Controller: RDC6445
Windows Version: 7
Accessories: Power Switch for air assist / exhaust blower, Ma meter with switch for external digital, dual digital temp gauge, LED lights under gantry and and and.

Pics and a list here. https://drive.google.com/drive/folders/ ... sp=sharing

I've mentioned it to him, but no real response. If you can back it up, all the more to you and him. I can't take full credit, I spotted it somewhere, may not have even been a laser video / web site. But by placing the target on the #3 instead of the #2, you are effectively creating a longer beam path to detect errors. If you have a nice tight beam, it may not be as significant, but I have a QC reject tube still, and the edges of the burn spot aren't well defined. That extra 700mm across between #2 and #3 allowed me to fine tune the #1 to #2 alignment.

Of course I discovered all this after I made some custom #2 targets... Only used three out of the full sheet...
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