Card stock curting settings - really frustrated here!

Having recently installed a new tube in the k40 and having re-built the head, cleaned and re-aligned everything I can now
Cut 3mm plexiglass at 30% or around 12mA at 8mm/s, but I do it at 7mm/s just to be sure and to smooth the cut a little. I can also do it at 50% or around 16mA at 25mm/s in 2 passes but the finished egdes are slightly ragged. That’s not my problem.
My problem is that I cannot cut through 2mm card stock no matter what I try or do! 30% at 10mm/s it leaves a decent but really burned mark. 20% at 4mm/s, again decent depth but burned. 30% at 60mm/s again, same. Multiple passess SORT OF cut deeper but 2 or even 3 don’t cut through. Before re-alignment and re-build of mirrors and head I was cutting theough the same card stock at 50% doing 25mm/s in 2 passes with really nice clean cuts. Did the slanted piece focus finding, so I’m at around 6mm below the nozzle (I have an air assist nozzle with 50.8 lens in there).

Frustrating. What settings do you use for cutting 2mm thick card stock?


I have heard but have not tried it myself is to do a scan instead of a vector cut.
By this I mean treat your cut as if you are rastering a picture.

Do you have a long air assist nozzle? That sounds really close otherwise. (Could you provide a picture?) Also your focus should be set half way into the piece you cutting for the best results.

Sounds to me like you are also struggling to cut 3mm acrylic. Typically I cut that at about 6ma and 10mm/s

Yes one of these

Bear in mind I cut plexi and 200gsm paper with exact same height and focus settings no issues whatsoever.

6mA @ 10mm/s you say? Ok then something is off.

Sorry scratch that. I was thinking of the some thinner acrylic I’ve been cutting recently. What you have sounds about right then.

So if I’m ok why is this piece of cardboard doing this to me? I did the slanted piece test on this particular cardboard and I’m using the thinnest section of line, which is the 6mm distance I mentioned before, still burns and charrs but not cutting through, even after 3 passes. I’ll play with focus some more.

Could it possibly be the material? Such as it being, or treated with, a flame retardant? How easily does it burn with a lighter?

Haven’t run across this before with lasering a paper product, but it reminds me of a time where a buddy of mine tried to burn some wood pallets in his out door fire pit. Went through a gallon of kerosene trying to get them to burn before we figured out they were treated with a flame retardant.

I would entertain that idea were it not for the fact that the very same material cut beautifully just a week earlier before the rebuild with 50% at 25mm/s in 2 passes.
Must be something with focus. Something that makes plexi cut better but card stock worse.

Make sure your focus lens is in correctly. It has two sides, a convex side which is a slight hump and the concave side which has a slight indent. The convex side should be up in a concave side should be down.