X-Y Cut dept is different

Hi, I was cleaning my mirror and lens. So I rechecked my alignment. The 3th mirror was off.
I set it to the optimal position and it cuts great again. But I tried to cut 22mm of wood (100w reci) at 5 mm/s 30%, 2 passes. It does the cut however the lines on the X-as are just not cutting trough, and all the other lines of the shape are nicely cut but charred. any thoughts??

grtz Fred

I dearly hope you are saying that the 3rd mirror alignment was off from where it needed to be to get the beam centered in the lens tube. Center of the hole into the #3 mirror is in no way shape or form associated with centered in the lens tube and on the lens.

Yes I was talking about off alignment of the third mirror. But the question is… why my machine cuts deeper when cutting trough wood in all directions but the lines across the X-axis?

Well, my first step would be to rotate the work 90 and re-input to the laser to see if the problem stays with the X or transfers to the Y. It’s not much of a change, but is splits the problem between the software and the laser.

If you are talking when it literally cuts a straight line across the X, then I would suspect you have something loose or to tight causing the assembly to ‘tilt’ just enough to take the beam off center. Too tight would put some stress on the rail bearings.

Again, rotate the input to isolate. If it’s strictly as the head moves on the gantry, your problem is in there some where.

Oh, and make sure your #3 mirror and lens aren’t shifting. I had a retaining ring that was about .5mm from as tight as it should have been. Took me two weeks to track down the little bastard.

Okay thank you Dave! I will try that and check it all.

Have a nice day!

If you’re regularly going to cut over 10mm, get a 76.2 or 101.6mm lens.

You just can’t do a good job with 2 inches. (My wife told me that).

Okay something to try out too! Thank your wife!

If you have the room and the tube to mount it in, go for a 127 or a 160. I’d have to link two tubes to mount a 160, so I’d just make the jump to a 190.5

You get increasingly greater beam area as you go up in lens.

My 101 is noticeably less effective at cutting than the 50 or 76 and terrible at engraving.

A 130W isn’t really enough tube for a 190mm lens and I’m struggling to find a need for one.

I’ve had customers with them, but they were cutting 200mm acrylic blocks with 500W lasers and needed to remove as much of the angle of inclination as possible.

The angle is a large part of it, but in different ways. Yes, you get ‘straighter’ cuts with the longer lens, but you have a deeper usable cutting depth as well. I’ll try a layman’s explanation.

For any given laser beam, you have the focus point, and up to X distance above and below the energy is still concentrated enough to be ‘usable’. With a 38.1 lens, the angle is pretty wide, so that X distance is pretty close to the focal point. As your focus length gets longer, that X distance gets further and further above and below your focal point.

That is why I can cut 6mm MDF with my 1.5" lens, but I can cut 9mm with my 2.5" lens. I’m waiting to finish a new lens tube holder to try my 4".

In case it wasn’t obvious, I’m probably not the target audience to put layman’s terms to.

Been at this, professionally, since the 80s, on the technical, R&D and service side.

Literally written books on the subject.