Noobie here with a question about cutting fabric

Noobie to laser cutting but I do have some experience with router and plasma cnc. I’m working on a project with J Tech 7W laser attached to a Shapeoko 3.

Here is my dilemma. If I lower the power of the laser it doesn’t start to cut until it has traveled some distance leaving me with an incomplete cut part. If I increase the power it cuts immediately but there is burning of the material. When working with plasma cnc I’m able to create a led-in to allow to compensate for this but I’ve learned this is not possible in Lightburn.

Any ideas on how to get through the material so I can cut at a lower power for less scorching?

As mentioned in my email response, you have 2 choices to address with the current release of LightBurn.

"LightBurn does not currently have an easy way to provide cut lead-in or out at this point although it is a suggestion with a lot of support from our users. You can add your support here:

To accomplish this task today, you would need to create the lead-in line and the ellipse as a single path."


you could also test using the ‘Cut Through’ mode…

This feature provides settings to allow additional “dwell” time at the start and/or at the end of the cut defined in the layer settings.

You can use cut-through with a very low (or zero) power. That’ll make sure the laser actually stops at the start and not just race in.

I created a lead-in line but the part is cutting from the outside in. How to assign the toolpath to cut from the inside out?

I’ll try this. Is there a ratio for cut through time or power vs the rate that the material normally cuts?

Have a look at the ‘Optimization Settings’ in the ‘Laser’ window for our cut planner options.

Thanks for the video, very helpful. I’m sure I’ll use a lot of what is contained in the video for future projects.

But for this particular project the cutting isn’t following the path as expected. For example, I created 3 layers of toolpaths and none of the tool paths are cutting from the inside out.

I attempted to attach the lightburn file but as a new user I’m not allowed to do so. If someone is willing to take a look at my file i’m more than happy to email it to you.

I have bumped your user level. You should now be able to attach your LightBurn file. Also provide screen caps of the entire LightBurn screen, the cut settings and the optimization settings. This will help in determining the issue.

Thank you!

Attached is a copy of my LB file. I’m trying to create my own lead in by having the cut start at the bottom of the line then travel around the part. LB is starting the cut on the part, then traveling down the line, before finishing cutting the part.

Right now the simulating is cutting at 100mm and 20% power. When I actually cut the part it was at 5 inchs and 10% on a 7w laser. Tool paths for both the simulation and actual cutting are the same using 2 different computers.

What do you mean by screen cap?

cut file.lbrn (11.6 KB)

You can set the ‘Start point’ of a shape and control the direct of the path using the icon on the left side toolbar. Click on new node to move start point. Shift-click will change direction of path. image

After I change strt point and direction for the first ellipse (on screen right), I get this in preview:

Pretty awesome stuff! I’m really close now. The only issue I have is during the simulation is the laser is doubling back alone the lines that connect to the circles and larger outline. Is there a way to not have it cut the line twice?

Yes, create your art with a single line. Noticed you have 2, one “up” and then one “back”.

Ahh…i’ll double check the design. My intention was to create it with a single line but Illustrator has done funny things to me in the past.

Thanks for all your help.

Using Lightburn how would I create a single line attached to the inside of a circle (so it is one continuous shape)? I used the divide Boolean in AI but as you can see it is not working right and is creating the double line.

I figured it out. For anyone doing this in AI you need to use the scissor tool and snip the ends then you can delete the returning path.

Again, thanks for all your help.