I recently got a small starter laser, the Creality Falcon 5w, assembled it, and was able to cut a few things successfully. I use a 24" piece of ceramic tile as a baseboard and operate in an open garage.
I’ve found that LightBurn’s perforation function is great for marking seam allowances, and I already cut a couple projects, one on a colorful fabric and one on a solid off-white.
(That’s a brown thread stitched into the marked perforations on the right side of the first photo, not part of the burn). These were cut with the wrong side of the fabric down on the base, and the right side facing up towards the laser.
However, when I went to cut another project today on a white piece of fabric, perforations were extremely inconsistent with some dots not showing up at all, as if they had been skipped.
Use the Preview function to see what the laser should be doing. If the marks don’t appear in the Preview, then it’s likely an interaction between the lengths of the Cut and Skip settings with the line / arc segment lengths. If you’re using scanned & traced images, the “lines” can consist of a zillion tiny segments that may confuse the perforation pattern.
However, some of the “missing” dots look like they’re present (and will appear in the Preview), but they’re not as dark as their neighbors, which suggests a combination of physical factors:
Color / reflectivity variations
Focus variations due to fabric texture / wrinkles
A relatively low-power laser
The key thing to keep in mind is that you’re working with a visible laser, so fabrics reflecting that color of light will absorb less of it and therefore not char as well.
The laser light is blue / violet, so fabrics on that side of the color wheel work poorly: a blue fabric appears blue because it reflects blue light very well. Light / white fabrics reflect all colors equally well, including blue. In both cases, those fabrics will absorb less of the laser beam.
Assuming the fabric absorbs the laser beam, it must absorb enough energy to get hot enough to char / discolor. This requires having the beam focused exactly at the surface of the fabric to put all the energy into one tiny spot. A wrinkle raising or lowering part of the fabric puts it out of focus, making the spot larger, which means the fabric under the (larger) spot doesn’t get as hot, so it doesn’t char.
But the fact that you’re getting pretty good results shows that you can use that laser to do what you want: it’s just a matter of getting all the fiddly details right.
I second the suggestion @ednisley gave, the inconsistencies are most likely caused by different reflective/absorptive properties of the fabric.
I do agree that Your results are very good for the first tries as well.
When using low power density to burn/char fabric fibers, the amount of moisture and oxygen plays a role as well.
Especially if there’s synthetic and natural fibers mixed together.
When I was researching wax evaporation (Gestetner stencils) about a year ago, I came across a method where some sort of liquid solution was used in order to improve consistency when marking fabrics.
Since marking fabrics wasn’t what my research was about, unfortunately I don’t remember where I read about that, and can’t fnd it anymore either.
Since the Google algorithms have taken leaps back when used for searching something meaningful with too detailed description, a search with minimum amount of words I could thnk of:
One trick that both takes care of the wrinkles and improves the consistency of moisture and free oxygen when marking/cutting paper or fabric, is to mark/cut through a sheet of glass.
As long as the glass is thin and free of any coatings, it is relatively safe to do so, but when lasering a reflective surface there’s always a slim chance that a portion of the beam will reflect back and damage the lens or the diode.
A simple vacuum table will get rid of the wrinkles, but increases the amount of oxygen in the process.
Thank you both so much for your fast and thorough responses, this kind of help is a rarity these days.
I did run the Preview function and found that all the perforations were there, so I started going through everything else.
I also thought that marking might be involved but I washed this fabric beforehand and upon closer inspection, the perforation misses have no correlation with the faint floral pattern on this one. As for wrinkles, the glass and the vacuum table sure do sound convenient, but I’d had good results with ironing with my first runs (I may still try the glass just to keep things from moving). I knew that color played a role but I don’t think I realized the extent. I knew that darker colors would be harder at least but you can see in one of my early runs that I was able to get similar results on both the blue and yellow parts of the fabric when cutting with the colorful side up.
With what was mentioned about blue, I do wonder if maybe the contact paper I put down on the tile base is affecting things. The tile is white and very shiny, and I had part of a roll left over that was the same size, and I figured it’d do the job. It’s blue, but has a pattern on it that’s blotchy and inconsistent, and when I did this cut I’d just rotated my base since the origin corner was too charred to make out the lines from previous cuts for alignment, so that blue would’ve been in full force, and a white piece of fabric is also going to let some of that blue color through.
The other thing I’d failed to consider is the high quality of this white cotton. It’s artisan stuff so the fibers are packed extremely densely, and since I pre-washed this one, those fibers are packed even more densely. This kind of fabric also has a slight reflective quality to it but I just didn’t think it would’ve been nearly enough to have an impact.
Which makes me think of what you said about environment and humidity. It’s been in the 90s and ridiculously humid all week and conditions were significantly better on those initial cuts. So I think i have my work cut out for me:
-Glass sheet or more thorough ironing
-Do not iron with steam, or iron without it afterwards enough to thoroughly dry it out
-use worse fabric
-wait until the weather improves
-bite the bullet and buy a honeycomb
-bite the bullet and upgrade (this is on the to do list but I want to get literally as far as I can with this one so that I know exactly what I need when that time comes)
Unless there’s better solutions to these issues out there, but I’ll keep looking. And thank you again for all the support!!
A few percent solution of borax dramatically darkens wood engravings, so maybe it would do the same for fabric. The only way to know is to try it out …
That’s unfortunately very true, but this forum is an exception to the norm.
Of course, there are some parrots and post count increasers, as well as the occasional spammers just like on every forum, but the former are pretty easy to spot, and the latter are swiftly taken care of by the moderators.
As for the colouring and its impact, the results on any colour other than white or blue (with blue diode laser) is going to be more consistent than on plain fabric.
The pigment carrier will also play a role, especially with synthetic materials.
So,
May not work as intended if its composition or colour used differs too much from the actual fabric You’re going to use.
That’s one option, but IMO better one would be to at least experiment in less than optimal conditions.
That way You have some data about the way the fabrics behaviour changes when the conditions change, and You can adjust the parameters accordingly.
While I personally do love honeycombs, IMO that won’t probably improve things that much in Your case.
With a steel honeycomb You can use magnets to keep the fabric in place though, so that’s a definite plus for the honeycomb route.
The major disadvantage of a honeycomb is that one has to have ventilation or at least crossbreeze under the honeycomb.
Otherwise volatile cutting byproduct gasses will eventually cumulate into the pockets, causing all sorts of problems.
Other disadvantage of (cheap) honeycombs is that they’re not flat, and without some sort of support structure, will droop sooner or later.
IMO no need to that unless You’re in a hurry or aiming for production quantities, 5W diode is plenty in Your application.
That’s a great plan
That’s possible, at least with natural fabrics.
I have a hunch that the one I read about was starch based, but can’t find it.
What I did find is that in industrial settings (ND-Yag, CO2) Sb2O3 (found in fabric flame retardants for example) can be used to improve markings in synthetic materials. Could work with blue lasers as well.
Just as with any other chemical in any application, safety first.
For those who may come after me-- it was the fabric. Fine, high quality quilter’s cotton has fibers that are packed way way WAY more tightly together and so more heat is needed than for the kind of $6/yd stuff you find at a big box store, and the differences were caused by the uneven coloring on my base-- this white fabric was thin enough that the color showed through. Wherever there was less blue, there was more perforation.