Splines show up segmented in autocad and do not display correctly in sheetcam

[marcus_sho]

Having an issue, when i create a file in Adobe illistrator and export as a dxf file, the dxf file does not display or cut correctly in sheetcam. It seems the splines change depending on what program is used to open in. Or if I open it in autocad the splines are segmented, if I explode the file it displays correctly in autocad, but when I save it as a dxf or dwg file it goes back to segmented. I have tried converting it to polylines in autocad but this is very time consuming. help on this would be appreciated. I have included some files to show the issues I'm having. I have also included the files.

wyoming script.dxf

(80.92 KiB) Downloaded 50 times

wyoming script.dxf

(80.92 KiB) Downloaded 50 times

wyoming script.ai

(184.71 KiB) Downloaded 53 times

wyoming script.ai

(184.71 KiB) Downloaded 53 times

[plasmanewbie]

Try using SVG files rather than DXF. I opened your AI file in Corel and saved as SVG and it looks good in Sheetcam. See attached SVG file I used.

wyoming script.svg

(10.13 KiB) Downloaded 54 times

wyoming script.svg

(10.13 KiB) Downloaded 54 times

[robertspark]

various CAD and CAM software does not like splines.

I suspect it is because they are 3D objects which can have a varying Z dimensions throughout its length.

If you are running CAD.

What I do is create a layer called "splines".

I then use qselect, and the dropdown menu to select "splines" and then select all.

I then change their layer to "splines"

I make splines the current layer.

I then turn off all other layers
( -la >> * >> OFF)

this keeps only the current layer active

then zoom out, type "PE" (poly line edit), >> "M" (multiple) and select all the splines with a crossing rectangle.

I then change all the splines to polylines.

_______________________

I use qselect to get rid of dimensions + hatch patterns too.... (but I use autocad in my day job for ~20 years)

[marcus_sho]

Try using SVG files rather than DXF. I opened your AI file in Corel and saved as SVG and it looks good in Sheetcam. See attached SVG file I used.

wyoming script.svg

Thanks I didn’t even realize sheetcam did svg files, this will help me greatly, the other issue I have is when I outsource to laser they get segmented splines, even when I convert them to poly lines I get a similar issue.


Thanks again!

[marcus_sho]

various CAD and CAM software does not like splines.

I suspect it is because they are 3D objects which can have a varying Z dimensions throughout its length.

If you are running CAD.

What I do is create a layer called "splines".

I then use qselect, and the dropdown menu to select "splines" and then select all.

I then change their layer to "splines"

I make splines the current layer.

I then turn off all other layers
( -la >> * >> OFF)

this keeps only the current layer active

then zoom out, type "PE" (poly line edit), >> "M" (multiple) and select all the splines with a crossing rectangle.

I then change all the splines to polylines.

_______________________

I use qselect to get rid of dimensions + hatch patterns too.... (but I use autocad in my day job for ~20 years)

Thanks, I’ll give that a try, but these are created and saved in 2D programs, the only one that I do in 3D is Solidworks and it gives the best file. I have had some luck setting viewres to a higher value in autocad, still segmented but it is better. I tried converting to poly line but it’s still not purfect.

Thanks!

[robertspark]

A spline is a spline.... Againsome cad cam packages do not like splines because they CAN change their z axis height many times across the splines length. The spline is a complex shape.

Simply because it CAN does not mean it does

And a few cad and cam packages simply ignore spline objects because they do not know how to deal with them because their geometry can be complex.

A line or polyline has simple geometry.... It has a defined start X,Y and Z and an end X,Y and Z... For each entity.

Yes a polyline is a continuous line formed of lines and arcs... But each of these objects have a defined start X,Y and Z and an end X,Y and Z so they can be converted to gcode as they contain defined nodes at each object junction.

A spline also has nodes but the curvature is blended BETWEEN the nodes

[marcus_sho]

Hi Robert,

Thanks for all the great info. I'll give it a try when I get back home. I've tried converting to polylines or even creating the text in autocad and converting to polylines and still seem to have the same issues. I'll try your method, hopefully that fixes it, wish I could just create polylines easily in Illustrator.

[robertspark]

If you send me the file with splines i will convert it and send it back

I use keyboard shortcuts and do in nearly daily

[SegoMan DeSigns]

The last time I ran into the spline issue on an outsource job, I found that autocad had a dongle to fix it posted on their site. Do some searching there..

[marcus_sho]

If you send me the file with splines i will convert it and send it back

I use keyboard shortcuts and do in nearly daily

Hi Robert thanks,

I have attached the main file, wyoming script from AI, dxf file.

I converted to polyline, everything looks good in autocad but when I send it to sheet cam all goes to crap again. Also any sharp corners I have to go back and manually fix, they get a little bubble on them.

pic showing bubble on sharp corners.

It did show smooth lines in autocad

And here is one of the issues, segmented lines.

[robertspark]

I "think" I know whats wrong....

If you import the dxf as a metric scale it will look like this....

If you import it as an inch scale in sheetcam it will look like this....

The problem with metric is the scale is VERY small....
The problem with inch is the object is small....

It looks like this when I try to do an outer offset with my plasma cutter settings.

The object is only about 1" x 1" in size..... you need to scale it up

[marcus_sho]

Hmm, that seems weird, you wouldn’t think scale would be an issue.

I’m having these parts laser cut, and using sheetcam as a stand in just to check the files, and to figure out what’s going on with segmented files.

Here’s what is being cut. Very small parts 3” tall, and the lettering all goes to crap. If you zoom in on the picture you can see the text is segmented.

I thought dxf files were not affected by scale, or is this more of a sheetcam, or CAM issue.

[robertspark]

Its a sheetcam setting (somewhere..). Ill look in a few hours and let you know

I think its taken from the post processor, ill have a play and get backbto you

Its not a dxf issue 100% sheetcam issue / setting

[robertspark]

Hmm.... oops

It may be an autocad issue.... when you convert the lines from splines to polylines, autocad asks you for the conversion precision.... the default setting is "10"


This seems to be ~10% accuracy (I think)..... basically it tries to curve fit a polyline to the spline.....

The setting can be changed from 0-99.... so with 99 you get a lot more nodes.

With plasma this is not normally an issue.... but because you are lasering something VERY small..... it makes a huge difference....

Attached is my updated converted DXF file for you, import it in inches it should be fine.

(sorry, file won't upload as it's too big now with all the extra nodes which smooth it out).

Its here for download:
https://drive.google.com/open?id=19TAh3 ... Odrvymhwad

[robertspark]

Oh yeah..... you may also want to improve the "Application" >> "Drawing Import" settings within sheetcam as you are doing very small detail work {it may help!]

2019-11-24 21_17_38-Window.png (14.59 KiB) Viewed 1644 times

2019-11-24 21_17_38-Window.png (14.59 KiB) Viewed 1644 times

[marcus_sho]

Hmm.... oops

It may be an autocad issue.... when you convert the lines from splines to polylines, autocad asks you for the conversion precision.... the default setting is "10"


This seems to be ~10% accuracy (I think)..... basically it tries to curve fit a polyline to the spline.....

The setting can be changed from 0-99.... so with 99 you get a lot more nodes.

With plasma this is not normally an issue.... but because you are lasering something VERY small..... it makes a huge difference....

Attached is my updated converted DXF file for you, import it in inches it should be fine.

(sorry, file won't upload as it's too big now with all the extra nodes which smooth it out).

Its here for download:
https://drive.google.com/open?id=19TAh3 ... Odrvymhwad

Thanks Robert,

I tried some different values, 41-99, still get the little bubbles on the end. I think this thread has helped out. Seems kinda drawn out but at least I can produce better files for the laser cutter.

[marcus_sho]

Oh yeah..... you may also want to improve the "Application" >> "Drawing Import" settings within sheetcam as you are doing very small detail work {it may help!]

Thanks, this will help for some of my smaller files and checking the files going to the laser cutter.