Laser cutting paper - please help

[Andrei George]

Hello everyone,

My name is George and this is my first post although I follow you for quite a while already. For about a month I am the owner of a Shenghui Laser Machine, 60 W with RDWorks V8.00.25. (The ammeter is set to 20 Ma with 100% power)
The reason I am starting this post is because I would need your advice as I have some difficulties in cutting paper without burn marks.
I read all the topics referring to paper burn marks and I applied one by one almost all methods described there (that’s what I’ve been doing for a month – trial & error J)
The paper I am trying to cut is metallic (pearled) paper of 250 g/ square meter and these are some of the things I tried:

• High speed (500 mm)/ low power (25 W)
• Aligning the laser beam to shoot straight in the center of the mirrors (dead center)
• Finding the focus distance using a piece of anodized aluminum
• Trying different types of paper -> same results

I always cut with air assist ON. And what I noticed is that the processing (cutting) time is the same even if I use a speed of 500 mm/sec or 150 mm/sec.
The power settings I have to use to cut 250 g paper is of min 20.4 W, max 22 W.
The best result I got until now are brownish edges and burnt angles (as per pictures attached).
I also attached a print screen with the user settings that the machine came with.
Please give me some hints on where I go wrong
DSC_0055.JPGcutting settings.jpgDSC_0056.jpg

[Rich Harman]

I can't help with the paper cutting part but with regards to the speed - I would work my way upwards to max speed rather than downwards. The laser will have a max speed that it can handle non straight lines. Probably less than 150mm/sec. Using a speed any higher won't be a benefit.

Are you using the 40mm lens? I would think that the shortest focal length lens is most appropriate.

[Andrei George]

Hi Rich,

Thank you for your quick response.
Yes i am using a 40 mm lens.

Thank you

[Bert Kemp]

Tell you the truth your pictures don't look that bad. Remember your trying to cut a very flammable material(paper) with fire (laser) Its the nature of the beast to get a little charring on the edges. More speed less power might help a little.

[Andrei George]

I know it is a flammable material, but these burns are very obvious in corners, reading the forum I realized that the paper cutting discoloration occurs, but here i have burns.
If i lower the power it will not cut the paper.
I read about ramp mode for cutting in corners but i can not find this settings.

[Barb Macdonald]

could you spray it with something first? I haven't tried paper, so zero experience, just paper mask for postioning.
Maybe letting the paper get moist, not damp, first?
Maybe increase the humidity where the paper is stored?
I'm thinking like a furniture spray, clear, maybe?
Good luck!

[John Noell]

...but these burns are very obvious in corners.

I don't know RDWorks but in LaserWorks the "minimum" setting seems to be what is used in corners. Therefore, I need to use a (much) lower minimum value to avoid burns in corners. Paper is tricky and you may need more speed (esp. for tight turns) than a Chinese machine has. The head on my Epilog is not nearly as massive as on my Shenhui which makes it easier to turn corners faster.

[Junior hall]

can you use a masking tape ( wide roll ) like they use in vinyl also known as transfer tape You can get some reasonable;e cheap on Ebay Cover the paper with transfer tape and then laser the paper that way you dont have any charring or burn marks The transfer tape is very easy to take off with out tearing the paper or you can also spray a mist on the transfer paper ( tape ) then lay it over the paper then laser it

[Andrei George]

Hi Junior,

Thank you for your answer, i will look for this transfer tape and try it (can you give me a link with this transfer tape, i do not know exactly what to look for) I hope there is just a settings problem and not a machine problem.

[Andrei George]

I don't know RDWorks but in LaserWorks

Hi John,

I think is the some program, RDWorks is the icon name of the program.

Thank you

[Junior hall]

Yes Andrei George here is the link as you can pick any one of these as i like the cheapest there is here is the link ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313&_nkw= transfer+tape&_sacat=0[/url]

also you can go to any sign vinyl shop and ask for a piece and tell them what your wanting to do as im sure they would give you a nice decent size piece to see how it works

[Keith Colson]

When I cut paper with my 60 watt Universal there is no burning at all. Two things I think you should check are.

If your laser is not perfectly in focus you can get burning. I spent a few hours focusing my machine to perfection. I used a high precision measuring microscope and adjusted my focus on paper until the line was as thin as possible. There are other methods but this method gave me the best results.

Try adjusting your PPI from the typical 1000 to 100 to 200. I have found things burn less at low PPI (pules per imperial unit (inch))

Cheers
Keith

[Andrei George]

Hi Keith,

I read your post on the forum about focusung with a microscope but i don;t have one and i use the method with anodized aluminum. I will make the focus test again. Also i read about the PPI settings but me laser did not have this settings, so i am stack just at speed and power.

Thank you.

[Keith Colson]

Something else to consider is, is your bed level to the laser head? Before I focused the machine I made sure the focus would be the same all over the table. If you focus a badly leveled machine it will only be in focus for certain parts of the bed.

Cheers
Keith

[Glen Monaghan]

Charring or darkened edges often means too much heat for too long, so try increasing speed as much as possible without messing up corners, lower power as much as possible without incomplete cutting, and use around 300-500 frequency or PPI or whatever the appropriate term is for you machine.