Inconsistent plasma cut patterns

[LucasWorx]

Hey guys. I finished my table build about 2 weeks ago and I'm in the fine tuning/experimenting stages with it. I've had a few really nice cuts but also some not so great ones. Yesterday, I tried cutting out an American flag. Many of the stars were just horribly cut out. Most of them were great and the machine is cutting fast with almost zero dross using Hypertherm book specs. Would anyone have some ideas on why a lot of the patterns cut great while some do not? The gantry feels stout. I did have to draw in some lines to the SVG file in Fusion to connect them, but would that cause this?

IMG_20221031_172711361 (1).jpg

IMG_20221031_172654440 (1).jpg

IMG_20221031_172643526 (1).jpg

[adbuch]

Please post your file (svg or dxf after you edited to add the lines) so we can have a look.
Thanks,
David

[LucasWorx]

No problem! Here ya go:

USAWavingFlag2.dxf

[adbuch]

While your file does have some issues, I don't see anything in the file that would cause the issues shown in your photo.
David

flag problems.jpg

[adbuch]

USAWavingFlag rev.1.dxf

Here is your file cleaned up, linked/joined, and smoothed to reduce node count.
David

[adbuch]

Here is what you file looks like when I open it. You might consider doing some node editing/clean-up with Inkscape, or perhaps import/export from Lightburn to link/join. LightBurn automatically links/joins upon export.
David

flag problems 1.jpg

[LucasWorx]

Ahh ok! I'm currently trying to learn inkscape as it seems like it might be easier to clean up SVG files than in fusion 360 but I'm not sure yet. Thank you so much for helping me out! I'll give your cleaned up version a try.

[Plasma-art]

How do you create the exported DXF in fusion?
There are a few possible ways that give some errors.

I always make a body, then a new sketch and project that body onto that new sketch and export that new sketch as the actual cut file.
This cleans it up dramatically.

[adbuch]

How do you create the exported DXF in fusion?
There are a few possible ways that give some errors.

I always make a body, then a new sketch and project that body onto that new sketch and export that new sketch as the actual cut file.
This cleans it up dramatically.

That's a good question. He mentioned Fusion for adding some lines, but did not say exactly what software he used to create the original file.

Question for LucasWorx: Where did you get the original file?

So he may have purchased the file (or free download from internet) and imported to Fusion 360 to edit, and I would expect to create cut paths and g-code as well (with Fusion 360).

[adbuch]

This looks like the result of a mechanical issue with your table or torch mount. Possible binding or loose torch mount. I would suggest mounting a sharpie pen holder to your torch and drawing the file on clean metal or paper at slow speed while watching your table motion very carefully. This may be a better way to trouble shoot than wasting metal.
David

star problems.jpg

[LucasWorx]

How do you create the exported DXF in fusion?
There are a few possible ways that give some errors.

I always make a body, then a new sketch and project that body onto that new sketch and export that new sketch as the actual cut file.
This cleans it up dramatically.

That's a good question. He mentioned Fusion for adding some lines, but did not say exactly what software he used to create the original file.

Question for LucasWorx: Where did you get the original file?

So he may have purchased the file (or free download from internet) and imported to Fusion 360 to edit, and I would expect to create cut paths and g-code as well (with Fusion 360).

You are correct. I downloaded the flag from Etsy and I used "Insert SVG" in Fusion. When I finished closing up the open lines, I right clicked on sketch 1 and chose "Save as DXF". Then I opened the DXF in Sheetcam to setup the cut.

Today I am going to install a different set of linear rails on my Y-axis and try doing what you said with a Sharpie. After hearing from you, I think you might be right about possible binding. I can't feel anything noticable when I unplug the steppers and move it by hand but The rails and bearings for that axis were not purchased together so I'll start there. I'll update this evening with results.

[Plasma-art]

You are correct. I downloaded the flag from Etsy and I used "Insert SVG" in Fusion. When I finished closing up the open lines, I right clicked on sketch 1 and chose "Save as DXF". Then I opened the DXF in Sheetcam to setup the cut.

Always extrude and make a body out of it, you will notice any errors imidiatly with open ends at that point.
After that make a new plane above the surface of the body.
Create a new sketch on that plane, press P for project, Chose the body option in the window that opens and after that actually select the body, hit OK and finish the sketch.
Export the new sketch as the cutting DXF.

That way you get a clean and fully connected DXF.
You might need to project it with lines as poly lines or not.
With some parts you actually want to project all the body edges instead onto the new sketch it depends on some factors.
just experiment with the projection window.

[LucasWorx]

Ahhhh...I see. Thank you! I'm still an amateur with Fusion so that helps. Initially, I did try to extrude but I was not able to and that is when I noticed the breaks.

[adbuch]

I would be interested to see the original file you purchased from etsy. I expect that it has many intersections along the paths which need to be joined/linked to produce all closed paths. With a file like that, import to LightBurn and then export and it will be automatically linked/joined. You can get a free download for a 30 day trial. Otherwise, post it and I will run it thru LightBurn for you. Some of these commercially sold files have problems as sold.

https://lightburnsoftware.com/pages/tri ... re-you-buy

David

[adbuch]

You are correct. I downloaded the flag from Etsy and I used "Insert SVG" in Fusion. When I finished closing up the open lines, I right clicked on sketch 1 and chose "Save as DXF". Then I opened the DXF in Sheetcam to setup the cut.

Always extrude and make a body out of it, you will notice any errors imidiatly with open ends at that point.
After that make a new plane above the surface of the body.
Create a new sketch on that plane, press P for project, Chose the body option in the window that opens and after that actually select the body, hit OK and finish the sketch.
Export the new sketch as the cutting DXF.

That way you get a clean and fully connected DXF.
You might need to project it with lines as poly lines or not.
With some parts you actually want to project all the body edges instead onto the new sketch it depends on some factors.
just experiment with the projection window.

Those are some great tips! Thanks. I don't really use Fusion 360 for cnc plasma, but I will check out your suggested process for dxf export. By the way, I did try you suggestion for lofting to create the 45 degree edge on that Shark tooth file. It works fine, but is much more work (at least for me) than simply putting a 45 degree chamfer directly onto the part.

David

shark tooth lofted.jpg

[weldguy]

I second the mechanical issue David suspects. Sometimes dry runs (plasma off) can help you to visually see and or hear the issue when it happens and may make it easier to spot the issue. Curious what you find.

[LucasWorx]

I would be interested to see the original file you purchased from etsy. I expect that it has many intersections along the paths which need to be joined/linked to produce all closed paths. With a file like that, import to LightBurn and then export and it will be automatically linked/joined. You can get a free download for a 30 day trial. Otherwise, post it and I will run it thru LightBurn for you. Some of these commercially sold files have problems as sold.

https://lightburnsoftware.com/pages/tri ... re-you-buy

David

No problem David. That would be much appreciated! I have attached the original SVG file. The pictures were grouped together in the file but the Flag that I chose to use was the one one in the top left corner. I deleted the unwanted ones out of the SVG.

[acourtjester]

I looked at the file and blew some of the stars up to look at the nodes. Attached are the screenshots of what I found. There is a unknown indicator of a node I don't know what it means. As seen in one of the screenshots there are many nodes piled on top of each other , not a real problem it just creates more than on line of code for it. There is another shown I have no idea what is means (red Arrow) and one of them what at a location of no connecting line in that part of the star. I do agree with David that it may be a movement problem, but it also can be a problem with this odd node being a software glitch from the drawing software moving from line drawing to vector. I would try the mounted pen for marking paper as a test.
Attached is 6 stars from the files to try.

star 6.svg

star 1.JPG

star 2.JPG

star 3.JPG

[adbuch]

wavy flag 1.jpg

wavy flag 2.jpg

wavy flag 3.jpg

wavy flag 4.jpg

wavy flag 5.jpg

wavy flag 6.jpg

[adbuch]

wavy flag 7.jpg

wavy flag 8.jpg

wavy flag 9.jpg

wavy flag 10.jpg

wavy flag 11.jpg

WavyUSFlag final.svg

WavyUSFlag final.dxf

[LucasWorx]

Oh wow, thank you so much! That's great!! Maybe I need to look into that light burn software. I'm anxious to try out this cut. I'll definitely verify with the Sharpie method first though. Unfortunately I had too much going on at work today didn't get as far as I had hoped today in swapping out my Y-axis rails. My next opportunity to finish it will be Friday. I will update with results as soon as I get the machine back together. I can't thank you guys enough for your help and ideas. I'm looking forward to coming back with some good news.

[adbuch]

You are quite welcome! Happy to help. The files I just posted are pretty clean, but you could go in and edit the stars to remove unwanted nodes as I showed above and Tom suggested. You can try LightBurn for 30 days with the free trial. It is great for file conversion with the link/join feature and is also a handy drawing editing program.

David

https://lightburnsoftware.com/pages/tri ... re-you-buy

[LucasWorx]

Does Inkscape not have features like that? I would still have to run it through sheetcam after making the edits, correct?

[adbuch]

Inkscape does not have the link/join feature. Design Edge has it, and LightBurn will do it automatically upon export as dxf. Yes, these are cad programs. Sheetcam will do your cam/g-code portion. So 3 steps: cad, cam, and post process to create g-code.

David

etsy 1.jpg

For comparison

etsy 2.jpg

[acourtjester]

Lucas Inkscape has the reduce node function it is called "simplify" under the path menu. As David points out to get a usable file for cutting some moving between different programs is needed. But some programs are able to do similar processes but they may call it by a different name, or may not have it at all. Info posted here shows this and member do speak of the software they use, some only come with a table and cannot be used by all.