Rough edges when exported to DXF file

[topkote]

Why would I have jagged edges in the cut patterns when I export a file as a DXF.

Here is what I am doing. I bring in a PNG convert it to Bitmap and export it as a DXF. The lines look smooth in Inkscape but when I open them up in the MyPlasm software the line look jagged and cut jagged.

Where am I going wrong?

Thanks

Mike

[acourtjester]

A file would be nice for us to look at it. If you have to many nodes in you file it can cause jagged edges, understand every node is a point for changes in direction. Less nodes make a smother path to follow with the cutting.

[weldguy]

Would be nice to see the dxf file. It is likely that your MyPlas software is unable to interpret certain aspects of that version of dxf file and could be replacing what should be a smooth arc with a series of short straight lines that follow the path of the arc. Post the file and lets have a look.

[topkote]

Here you go folks. These are the files I am working with.

Thanks,
Mike

[topkote]

Here are some pictures of the rough cut I am talking about on the actual piece.

[acourtjester]

I looked over the first file in Inkscape and it looks ok more nodes that I would like but not enough to cause the problems in your images. I would look for a movement problem with your table or a electrical noise problem. In your images there are straight cut that look fine but places where the X and Y are moving together it is very bad. Simple check is cut a box shape then rotate the box 45 degrees like a diamond shape and cut it. I bet you will see the sides of the diamond with ripples in it.

[adbuch]

Here you go folks. These are the files I am working with.

Thanks,
Mike

Mike - I don't see any problems that jump out at me looking at your first file with Inkscape.
David

[adbuch]

Mike - I also don't really see any problems with your final version either.
David

[adbuch]

And this is what your final version dxf looks like when I open it with Design Edge.

Lots of discrete intersections and several overlaps. Here is what it looks like after linking/joining and some minor editing to eliminate overlaps and open paths.

rabbit run cottage framed final dxf rev1.dxf

(119.36 KiB) Downloaded 57 times

rabbit run cottage framed final dxf rev1.dxf

(119.36 KiB) Downloaded 57 times

[adbuch]

I don't think your problem is necessarily with your file. If you try cutting the dxf I posted above and you still have the ripples and rough edges, then I would suspect that you have mechanical issues with your table. Slop in the belts, gears, etc. A good test to do here would be to mount a sharpie in place of your torch and run the program and physically watch the tip of the pen as it draws your shape on the metal of paper. This will make it much easier to spot problems as opposed to trying to watch the torch while it is cutting.

But I have seen some who have had problems with inkscape files in sheetcam. My solution is to use LightBurn to open your svg and then export as dxf. Lightburn will automatically link/join your file to eliminate all those discrete intersections. This has helped several members before with similar problems.

LightBurn cost is $65 for a perpetual license, and well worth the minimal cost.
David

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

[adbuch]

Why would I have jagged edges in the cut patterns when I export a file as a DXF.

Here is what I am doing. I bring in a PNG convert it to Bitmap and export it as a DXF. The lines look smooth in Inkscape but when I open them up in the MyPlasm software the line look jagged and cut jagged.

Where am I going wrong?

Thanks

Mike

It would also be helpful if you would post a screen shot of what your file looks like when you open it with MyPlasm.
David

[adbuch]

I looked over the first file in Inkscape and it looks ok more nodes that I would like but not enough to cause the problems in your images. I would look for a movement problem with your table or a electrical noise problem. In your images there are straight cut that look fine but places where the X and Y are moving together it is very bad. Simple check is cut a box shape then rotate the box 45 degrees like a diamond shape and cut it. I bet you will see the sides of the diamond with ripples in it.
rabbit run 2.JPG

Tom - that is a great tip!
David

[weldguy]

I agree with these guys, likely not an issue with your file but rather the machine movement.

I suspect this could be caused by your auto torch height control or THC. I would try cutting a profile both with and without THC and compare the edge quality. Super fast and easy to do and definitely where I would start. If it cuts clean with THC off we need to look at your THC settings.

If it still cut rough with THC off we will need to look at your equipment for loose parts, slop, bearing too tight, etc.

[adbuch]

I don't believe that small variations in cut height will cause the edges shown in the photos. Early on I had problems with my Plasmacam doing the "sewing machine" thing and the edge quality was still fine for sheet metal. This problem was caused by having the ground cable (work clamp cable) coiled up next to the cutter.

It is much more likely that you have mechanical issues with your table. Just my opinion, but time will tell.
David

[weldguy]

I don't think it is a small variation height causing the issue but rather the sewing machine effect as David puts it. The THC oscillates the torch up and down at a rapid rate and cause the torch to vibrate. A super tight machine it may not have a big effect on edge quality but a machine with slop in the mechanics or a flimsy torch mount would definitely be an issue. The THC check I suggested first because its a quick and easy check and if your THC is oscillating you really should get that solved first and then move on to find slop in the mechanics.

[adbuch]

The sewing machine action is typically at very slow frequency, so most likely not enough to cause vibrations with the Z axis torch mount. Also, this does not occur with all machines. For example, coiling up the work lead did not cause problems with my 45xp. It only occurred with my powermax 85 - which produces much more noise from the power supply switching. And unless the OP has a large cutter and has coiled up his work lead, then this should not be a problem.
David

PS - Here is a short video showing my machine doing the "sewing machine" thing. It is quite evident at the beginning of the cut if you look closely.

https://www.youtube.com/watch?v=c6p4Cqu-0Ns

[weldguy]

Watched your video David, yes your oscillation seems very mild, I have seen it get much more aggressive and pronounced than that on other equipment. I understand the cause of your oscillation was due to a coiled up torch lead but many things can cause this. Just having the THC settings set up poorly can cause aggressive oscillation action. The Pcam THC is a decent design and fairly foolproof however many of the aftermarket THC systems not so much and this can be a common issue. Not sure what the OP has for THC but cutting with THC on and then off would help to clarify if the THC was in fact the issue in less than a minute. Maybe he will post back and let us know.

[topkote]

Ok folks so here's the follow up on my issue of rough cuts on a file that I brought over into MyPlasm from Inkscape.

I followed the advise of you folks by moving around my ground cables to make sure they weren't coiled up. I tried cuts (the squiggly photos of the tree) with both the THC on and off. Still had the same problem. I them make some test cuts star, circle, straight lines from a file I got off here and they appeared OK. I then made a cut of the F-Bomb opener that also looked good. As mentioned I never have had a problem with any files until in started modifying and bring my own files into the MyPlasm program from Inkscape. I appears that I am doing something wrong with Inkscape. Check the photos, your thoughts?

[adbuch]

I don't really see how the problem could be caused by Inkscape. I will do a trace of your photo with DesignEdge and supply you with the dxf file just as a check.
David

[adbuch]

RabbitRunCottage from DE.dxf

(326.62 KiB) Downloaded 52 times

RabbitRunCottage from DE.dxf

(326.62 KiB) Downloaded 52 times

[robertspark]

the exported dxf file in the first post from inkscape uses linear lines and not arcs.

the linear lines are probably not conducive to the myplasm system because it may not have a blended (g64) tolerance system so it it accelerating and decelerating between each line section leading to jerky motion.

it may also be a lookahead issue with the my plasm system where it is not able to effectively blend the motion.

I would suggest it's a mixture of inkscape (converting an SVG to dxf.... I will check for a setting which will increase the number of segments)

and the myplasm system not being able to blend the motion or have sufficient lookahead and motion blending (g64)..... I don't think that you are likely to sort that unless there is a setting for g64

[adbuch]

the exported dxf file in the first post from inkscape uses linear lines and not arcs.

the linear lines are probably not conducive to the myplasm system because it may not have a blended (g64) tolerance system so it it accelerating and decelerating between each line section leading to jerky motion.

That is a good clue, and great observation! Here is the original file that he started with.

viewtopic.php?f=6&t=33631&p=208407&hili ... ge#p208407

Rabbit Run Cottage.svg

(19.7 KiB) Downloaded 51 times

Rabbit Run Cottage.svg

(19.7 KiB) Downloaded 51 times

Here is his final SVG file from above opened with Inkscape. It still has smooth curves.

Now - here is his dxf final version opened with Design Edge. Notice the discrete individual straight line segments.

And here it is opened with LightBurn.

[adbuch]

Now here is his final svg - opened with Inkscape and exported/saved as dxf. No more discrete straight line segments. So my conclusion is that the problem is not with Inkscape exporting/saving as dxf, but rather some other processing done by the OP that we may not be privy to.
David

Rabbit Run Cottage Framed Final svg exported from Inkscape as dxf.dxf

(621.56 KiB) Downloaded 41 times

Rabbit Run Cottage Framed Final svg exported from Inkscape as dxf.dxf

(621.56 KiB) Downloaded 41 times

[adbuch]

And here it is after linking/joining and some minor editing to eliminate open paths and crossovers. There are still discrete short line segments making up the curves, but they are much smaller and should not cause any problems for cutting.
David

Rabbit Run Cottage Framed Final svg exported from Inkscape as dxf linked.dxf

(559.92 KiB) Downloaded 42 times

Rabbit Run Cottage Framed Final svg exported from Inkscape as dxf linked.dxf

(559.92 KiB) Downloaded 42 times

[robertspark]

it may be that he has opened the dxf in myplasm and saved or exited that software and it has converted the poly lines to straight line segments between the nodes.

I have never used myplasm so please take the following with a big pinch of salt but I suspect that it is a very rough and ready controller and does not offer some of the features that mach3, mach 4, uccnc or linuxcnc offer.... but it is an integrated solution purely for plasma and a cost effective one (low cost + all in 1 box).

when I first started with plasma I did buy and use the proma THC 150 torch height controller and in my opinion it was very rough and ready and would not adapt to thin and thick material cutting as it could not respond fast enough on 2mm mild steel, but was fine on 6mm mild steel (under mach3 with an ethernet smooth stepper)

good luck and I really hope I am wrong as I don't think that proma will sort the issues for you and update their software.... hence why I now use linuxcnc and am no longer at the mercy of hardware or software and associated short comings and slow or non existent product development and improvements. that is not to say that Linux or linuxcnc is easy or simple or better... just that the user (me) is now in the driving seat and it is what I make of it as it is fully customisable (even if it took me a lifetime to understand and change it!!!!).... luckily there is usually someone to help and point you in the direction of what to change