Issue is 2mm alignment delta when pulsing only on the Y-axis.
Transom rails and side rails are square,
Axis of travel and the X-axis is right on top of each other, and this delta is the same on both sides of the Y-axis left to right.
Belts are tight.
Rails are lubricated.
Has to be some kind of adjustment? Is this a motor adjustment?
30x40 Omtech Red and Black CO2
It took me a long time to understand what you were showing here so let me make sure I’ve got it. It seems you’re not able to reliably get back to the same physical position on the bed after making moves of the laser head.
So in your diagram you’re saying that in Pulse #1 you’ve moved first to the upper right, then came back to “center” and did a laser pulse? Then on Pulse #2 you went to the Upper Left, came back to “center” and pulsed again? And you repeated the same for #3 and #4?
And the problem you’re highlighting is that the laser doesn’t seem to be getting back to “center” especially on the Y-axis.
Can you confirm this is the situation? If not, please clarify.
If this is correct this seems like it could be an issue with backlash. Check that the pinion on the steppers are held firmly to the stepper. Recheck the grub screws there. Manually move the gantry back and forth along the y-axis. Is there a lot of “slop” before the stepper are engaged?
Another thing could be if the stepper is not staying engaged that it could be “relaxing” and losing position.
What kind of controller is this on?
Simply, I align the system and that diagram is shooting in sequence all 4 corners as shown in the diagram. The head is aligned along the axis of travel like normal. But I orient my work in the upper right and it shoots fine but when it gets toward the bottom is is out of focus by 2mm. Thats the confusion, if the axis of travel is established you would think the distance would be the same as it travels in the Y axis no matter what. here is 2 pulses 1 in the upper right and 1 in the lower right
Where are you burning this to? Is this attached to the laser head? So this question is about mirror alignment?
Not really. This image is on the head, but the mirrors are aligned perfectly. Next is is a series of pulses from the gantry centered in the Y axis and pulsing from right to left 3 times. [the red glow is the center. I use a photon alignment tool with tape over it to give me my center mark consistently and I have Parkinson’s and drawing a centered dot is a challenge to say the least. :)]. First far side,
and then close to mirror 2.
Okay. I’m now with you.
Can you indicate position of laser, m1, and m2 in your diagram?
Also, is X your vertical axis or is the diagram rotated 90 degrees compared to the actual laser?
By the way, it’s great that you’ve found tools to allow you to keep lasering in spite of the Parkinson’s.
Here is a new diagram that may help. The issue is so hard to explain. The diagram is looking down from the top but the images are of course looking at the head
You’d laugh at what modifications I have had to make to accommodate for my PD. I call it Banjo machining, but it has worked well. I have been dealing with this issue since I got the machine a year ago. I’m not sure if I dare show you the changes…you brave and open minded?
Haha. If you told me you built the whole laser around you I wouldn’t care.
I’m carefully considering your symptoms and the available evidence. I know you’ve done a laser alignment but I’m inclined to think that either the laser tube is not perpendicular to M1 or M1 is aimed very slightly inward towards the machine. Just enough to cause the offset Y in Pulse #3 and #4.
Did your alignment process include checking M2 in the Pulse #3 position?
Apologize but I’m not familiar with the Photon alignment tool.
Looks like you have a Otur Laser. Sometimes I regret going CO2 from the diode laser, but I kept burning up the diodes. I am (and was) an artist and Parkinson’s kind of put a dampener on that so I create with the laser as it gives me the ability to create with a steady trim. here is a project I just finished. The first image is the small moquette size for testing then the final one. Took me a month to build but for an old shakey dude it turned out funny.
final size of crazy santa is 48"x48"
Loving the ornament 
I have a smaller OMTech. I found that the drag chain/cable chain was improperly installed and causing the gantry to bind as it went to the lower right. I put a 1/4"nylon spacer washer on the head under the drag chain to help relieve the binding. Seems the drag chain should have been another link long.
I considered something like this here but thought that this would only affect the lower right. In that it should only be in the constrained chain scenario where the bending occurs. However, you can see that the lower-left shows the same issue so ruled this out.
Am I thinking of this correctly?
Since there are 2 drag chains, I’d check out both! Good luck. By the way, Russ Sadler of sarbarmutimedia on YouTube, detected the same drag chain problem on his Chinese blue laser. If you have not checked out his YouTube channel- please do so, there over 180 videos on his laser learning journey.
thanks, hope it made you laugh.
The alignment tool is from American Photonics, and shoots a laser beam backwards and helps align the axis of travel. You’re supposed to remove it when pulsing, but I got the idea to cover it with tape to protect it and use it as a target. With Parkinson’s I tried just about every idea to make a target for alignment that didn’t require marking, or trying to place by hand a small disk in the target hole. 
I’ve reviewed some material from American Photonics and I think I understand the system. I think my theory on M1 to M2 alignment still holds.
I think you’ll need to adjust M1 every so slightly clockwise if looking at it from the top.
You could test this directly by doing the spot test on M2. If my theory holds, you should see a lateral difference in spot location in upper left vs lower left.
