Odd? Problem

I am new here as well as to the laser world, I bought a K40 in December 2019, and have it set up (finally.) I have a problem when engraving.
K40 laser w/ analog amp meter, air assist, honeycomb bed , focused, mirrors aligned, water cooled, plenty of exhaust, using Inkscape to design, whisperer to engrave.
Problem: When engraving(Raster) a small 4"L(x) x 3" W(y) piece I get a heavy burn on my engraving on the right side towards the middle. this only happens when I set it up in the upper left portion of my bed. Lower right burns just fine. What am I missing?

If, with the unit turned off, you move the head left/right in that particular area, does it feel any different than other areas of the bed that engrave well?

What about lower left or upper right?

If you look closely at the left side dark text it’s actually ghost engraved. Most likely it’s an optical alignment issue since it gets better as it moves to the right. The ghost splitting is most likely due to the beam clipping the inside edge of your air assist nozzle (or possible a mirror mount).

So check that your mirrors are all properly aligned around the bed and that the beam is exiting cleanly through the air assist nozzle.

The ghost engraving could also be caused by a damaged lens or mirror so check those as well.

Let us know what you find and we can go from there. Let me know if you have any questions.

Michael-There is a slight bump/hump in the y axis rod with or without the drag chain near the problem area.
The curious thing is larger font comes out perfect.
Lower left and upper right engrave just fine.

Ned- optics are clean and appear to be aligned. Why is larger font not affected? if the beam was not exiting the nozzle properly wouldn’t the whole engraving be affected?
I really appreciate your guys help with this. I feel I am so close to having a proper working laser except for this issue.
Wayne Kuhn

My guess was a bit of drag on the X axis in that area and engraving in both directions so that the drag pulls it back as it travels in each direction. If that’s the case, engraving at a slower speed would likely reduce the impact, and engraving at a higher speed would likely make it worse. It does look like it is offset not only left/right, but also a little bit up/down, which would make sense for the mechanism racking slightly under certain loads.

It still looks to me like a mechanical problem, but I don’t have any good ideas why it would affect only that corner.

So I’m not much use here, sorry. :frowning:

@Wayne, your design is 4x3 , could you try to engrave 3 of those in line. (K40 bed is 12)
That way you will be able to determine if your problem is alignement issue (just the left one) or a design issue (repeat 3 times the same error)

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The problem only exists in that one area (upper left). The odd thing is larger text engraves just fine.

Can you provide a picture of the large text engraved in the upper left?

Here is the larger text aprox 8 in x 8 in on 1/4 in ply. The original was aprox 4 x3 on hard maple.
I see no problem with the larger text. But zi may be missing something a more expirienced eye will catch.
Once again I really appreciate any input.

BTW, I am not trying to bring religion into the group, this is a project for a local boy scout troop to sell on Easter Sunday
I am not a zealot :slight_smile:


I could be wrong, and I’m not an expert, and it could be an artifact of the photo, but the “Blessed” and “make” below it look to me like they are affected by the same problem. I’m particularly comparing the second “e” in “Blessed” to the “e” in “slumber” because the “e” is sensitive to the diagonal ghosting effect. @nedman your thoughts?

No apologies needed! Our site rule is to keep it clean so parents are comfortable having their children follow along and become the next generation of makers. We don’t complain about religion or lack thereof. :slight_smile: