HELP PLEASE: Power loss further from origin

Long time reader, first time poster. Apologies if this is the wrong Forum branch. I’m just learning my way around here (and love the software and community surrounding it).

I have an Orion Tech 60w Laser and I love it. However, I see significant power loss as the head moves further to the right of the origin. I’ve done a LOT of Googling and either I’m using the wrong terminology or other people don’t have the same issue.

While it definitely manifests itself after the lens and on the work material, I also know that it’s losing power before the lens assembly. I can see this when I put a piece of tape over the mirror guard on the head portion and fire it at the origin and at the furthest corner. When it’s at the origin it takes one or two pulses to mark the tape and make it smoke. Furthest corner: I have to hold down the pulse until it eventually burns a hole that’s a touch wider.

Further complicating things, it loses some power from the 1st mirror to the 2nd as it moves from origin, but loses the most power between mirrors 2 and 3. The beam looks to get wider and burns the target tape much more slowly. All this before it even gets to the lens.

All in all, it cuts a clean, straight line through most of the bed, but when I get to the right 1/5th I have to really slow things down and boost the power to get the same results as elsewhere.

Things I’ve done/tried:

  • Double checked alignment on the mirrors. They are hitting the same point all the way to the laser head and not on the edge (relatively close to center)
  • Cleaned the mirrors
  • Replaced the mirrors
  • Tried it with pulsing different powers
  • I haven’t adjusted the aiming on the tube itself, but I’m not sure that’s possible with the mounts it came on. If anyone knows how to do this, I’m all ears.

What adjustments am I missing? Is something defective? Is this a normal thing?

Thank you in advance for your help! Let me know what other info I can provide to help solve this riddle.

I promise I’ll post some of my work soon. :smile:

It could be:

Dirty mirrors
Mirror Alignment
Chassis/bed alignment.

Without a power calorimeter, you’re only guessing.

+1 to what @Bonjour has replied with. Optics is the culprit in almost every one of these cases. Bed alignment next.

Yep. I agree with the above. Cleanliness & alignment.

Wow! Thank you for the quick replies!

It’s very likely an issue with what I’m doing, but I’m at a loss as to what I’ve done wrong.

My thoughts:

  • Mirror cleanliness - The mirrors were clean, but to double check I installed new mirrors and got identical results (I even wore cotton gloves while installing to ensure no finger prints)
  • Mirror Alignment - I believe I’ve aligned the mirrors properly, so I don’t think it’s the mirror alignment. I’m hitting pretty close to center with no variance of location in near and far targeting. But I could be wrong on this being an issue. If the laser is hitting the same spot on some targeting tape on the mirror guards throughout the bed, wouldn’t that indicate that they are properly aligned?
  • Chasis/Bed Alignment - I don’t think it’s the chassis/bed alignment since the laser is hitting the apertures in the center on all mirror assemblies throughout the distance traveled and they match up near and far from the origin. And it’s definitely happening before the lens. I can see the difference on some targeting tape on the lens guard of the 3rd mirror near and far from the origin (both time taken to burn a hole and size of the hole burned) That all being said, I’m not as familiar with the issues with bed alignment. What would bed/chassis alignment have to do with it if it’s losing power before getting to the lens?
  • Lens Focus - The lens has no issues focusing the beam at the far side of things. It still aligns with where the targeting assist laser hits and makes a pin point through a piece of paper
  • Power Supplied to Laser - I have an amp meter hooked up. Not a big surprise but the power feeding the laser is consistent regardless of the location of the head

When hitting a piece of tape or paper at the far end of things before the 3rd mirror it appears to make a bigger hole (maybe 1 to 0.5 mm difference), but that may be because it’s taking longer to burn a hole in things.

How would a calorimeter help (not that I can afford one)?
Any more ideas for diagnosing the problem?
Or… do you live in the Seattle area, have a calorimeter and dying need to solve a perplexing problem? :wink:

And again, thank you for jumping in to help. I really appreciate it.

Also, does anyone have a good link to some info on checking bed/chassis alignment that they like?

I’m having trouble googling info on it as what little I’ve found is buried under a mountain of mirror alignment articles.

Bell-Laser are in Seattle. You’re lucky.

The way to check your mirrors is from the furthest extent, back.

Set mirror 1, then move Y to the left-front position and set 1&2 to dead centre

You can then move Y to top left and see if there’s any variance.

Move Y back to front position, and X to furthest extent - repeat.

For the X-axis mirror, you should be aiming in the centre-line vertically, but about 2/3 down horizontally, as well as making sure your lens tube is accurately vertical in X and Y.

Often overlooked, the accuracy of the level of your tube is very important as any divergence will be magnified through the furthest extents.

When setting up a new machine, in order:

Set the base and chassis accurately level at all points - 4 corners and across both X and Y axes. This becomes your reference point and will allow easy checking of the rest of the machine. Ensure all mounting points for rails and bearings are firmly tightened - the less slop before you proceed, the better. An electronic level is much more accurate than a spirit level. Accumaster are what I use:

Check the mounts and the level of the tube. it needs to be spot-on. Adjust as necessary.

Check the height of Mirror 1 to be central to the levelled tube. Adjust as necessary to set height and angle towards M2 - at it’s furthest extent. spot test at 3-4 points along its travel using the same piece of paper or tape without moving it from the mirror. Any variation in Y axis trueness will be shown up as the beam will change relative position as the head moves Y-Y.

Repeat for M3

Ensure the beam isn’t hitting the inside of the lens tube - again, an electronic level is very useful here. I have an electronic angle gauge which I also use.

By working from the furthest extents back to closest ensures you get smaller and more accurate as you move the head back towards the beam source, not worse, and end up chasing the beam.

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Holy cow, that’s a thorough response! I’m going to work through it and get back to you.

Thank you so much! (But don’t let my appreciation stop more help)

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