help needed with dxf not coming out true in sheetcam

[charlie chop]

Hi all, Im having problems when some dxf's into sheetcam the text comes out different ( ie the corners get chamfered), but doesn't happen in the same place on the same letters.
Im unsure whether its due to the design and editing text, or in sheetscam.
Any ideas would be much appreciated.
FYI the design is done on Vectorworks CAD

'(unsure if screen shot of sheet cam will work, only just worked out how to do it)

[acourtjester]

HI
I have had sort of the same problem with TurboCad what I do is save it in .svg file format and it comes out correct in my case. This seems to happen if I try to configure the text in a non-normal way (arch form) but not all the time.
I loaded yours into turbo can and saved it in DXF and SVG and both look normal. Here is the DXF but cannot up-load SVG here.AS you can see the scale is very large in sheetcam.

[charlie chop]

Thanks ill try that.
I don't know why sheetcam cuts the corners, when I reopen the dxfs they are how they are supposed to be.
I'll see how It goes
Cheers

[Largemouthlou]

looks good here, I did have to open i in auto cad 13 and import into corel4 to scale it down some. But it did open fine with no champers in sheetcam as downloaded from here.

[charlie chop]

OK turns out Vectorworks cant save as SVG file and after trying a bunch of things, I found an answer,
If I 'convert to lines' then do the usual export to dxf, when it opens up in sheetcam it is how it is supposed to be.
So all is well in the world again, still has me stumped how the DXF file can look one way but when that same DXF file is opened in sheetcam it looks different.
Anyways its fixed . cheers for the help

[beefy]

I get that exact problem regularly, chamfered corners. I often revert to SVG instead but it's very annoying that something of accuracy gets screwed up in cad/cam (which one ??).

Most of the time I'm exporting the DXF from Coreldraw and importing into Sheetcam, but don't know if the DXF export is bad, or if the DXF is OK but Sheetcam is not importing it properly.

Keith

[tcaudle]

DXF is the format from Hell. It is controlled and changed (at their whim) by AutoDesk. There are two sides to a DXF file transfer. First the EXPORT. Most 3rd party programs won't export things like Polylines (splines). You typically have to back down to older DXF versions to get things across.
Then the IMPORT
CorelDraw handles DXF poorly. It will import but not perfectly.; Its export uses line segments instead of arcs and curves. SheetCAM does it's best to try and put it back together but has hundreds of straight lines to try and join. DXF without splines is just a collection of "objects" each with a start and stop node and the import has to try and determine how close the nodes have to be before it considers them joined. To lose and you get things joined that should not be. Too tight and you may have open paths. The possible solution for Corel is to get the DXFTools from CorelDrawTools.com It won't help Corel IMPORT a DXF and it won't fix a bad drawing, but it will take a drawing in CorelDraw with the Bezier curves and put out valid arcs and circles. It even handles Fonts without changing them from text to lines.

There are dozens of formats better than DXF. Problem is that most pure CAD programs cannot use them. Adobe has been a leader in not only vector drawing tools but precise vector file formats. Most notable are Postscript (EPS, PS) and AI out of Adobe Illustrator. ironically Adobe Illustrator Exports DXF poorly (segmented) You will find vector clipart for the sign and printing business are in either AI or EPS format. You can get clipart from www.vectorart.com in individual files or as mega collections.

The sign industry figured all of this out years ago and barely knows what a DXF is. If you cut decorative plasma with lettering or decorative shapes you are in the sign business whether you realize it of not!

What to do: Work in stable , open vector formats. Try to get any artwork you need in AI, EPS, WMF, CDR. SVG. If you buy artwork (clipart ) and need to edit or add anything to it see if you can get it in a format that is not DXF. Avoid the cheap collections you see on EBAY that are usually poor autotrace files of bitmaps (that are ragged when you increase the size to cut)
SheetCAm handles SVG from Inkscape very well and even DXF from Coreldraw using DXFtool if the clipart is one of the above formats. CorelDraw and Inkscape are pretty good inport/export tools and both support using Windows Fonts and doing things like welding objects and wrapping text along an arc or circle pretty easy.

If you learn to edit, draw and scale in a true Drawing Program that will let you export in a format that supports polylines and arcs and circles then your computer time goes down and your profit goes up.

We started a decorative plasma cutting business in 2002 and turned it into a profitable business for several years by focusing on custom "signs" and learned a lot of stuff along the way. Key to that was spending as little time in front of the computer and more at the plasma table. You will find that what YOU think will sell (designs) is not the same as what your customer will pay for. Most of the jobs end up with something not in ANY general clipart collection no mater how many you have. You have to learn to use the drawing tools and to be able to hand trace a bitmap (photo, scan. internet image) and not depend on autotrace tools that only work well on high contrast, high resolution images with low detail.

Sorry if I stepped on any toes but there is no substitute for experience.

TOMC

[acourtjester]

Thanks TOMC I'm sure that explanation will help I wondered why some clip art drawings had so many nodes then others.

[btburn]

I have the same problem, It just clips the corners on some parts. I'll try all that out next time.

[beefy]

I have the same problem, It just clips the corners on some parts. I'll try all that out next time.

Just remembered a tip someone gave here a while back. On the troublesome corners, try adding a tiny fillet, something that won't even be seen. As far as the software is concerned though it's not a corner anymore, and that clipping doesn't occur.

Keith.

[charlie chop]

Yep the little fillet works well but a pain to do when there are lots.
i went to cut to cut my logo out today that I normally do on the vinyl cutter sticker machine (eps file) logos turn out perfect as a sticker, put it into sheetcam and every corner was cut off, it would of looked like I'd cut it by hand. Ill look into the other file types as I do a lot of scripts and its just hit and miss how it will turn out.

[acourtjester]

what was the post processor you used in SheetCam Have you tried other ones.
I built a small table for my daughter and put a drag knife on it I used mach 3 and I told it the tool was .002" in diameter(rotary tool) to cut vinyl. You could play with it if you put a pen in place of your torch to save material.
Also you could contact Les at SheetCam via email he seems to reply the next day.

[beefy]

what was the post processor you used in SheetCam Have you tried other ones.
I built a small table for my daughter and put a drag knife on it I used mach 3 and I told it the tool was .002" in diameter(rotary tool) to cut vinyl. You could play with it if you put a pen in place of your torch to save material.
Also you could contact Les at SheetCam via email he seems to reply the next day.

The post processor doesn't affect the import of a DXF file into Sheetcam.

Keith.

[Marty]

tcaudle wrote: DXF is the format from Hell.

Mr tcaudle you could not have written a better summary post more accurate and bring in the hints and hell about dxf files. I just read it last night....your comments mirror 100% what i have learned......I am thinking of switching to SheetCam from Enroute for CAM functions..anyway you have it all there....I use Corel Drawx6, with DXF Tools Professional from Leonard Software to export from CDR to dxf as polylines, and if I use pres designed purchased templates in my design, I bring them into CorelDraw as an EPS, NOT as a DXF.....after design, then export to dxf via CorelDraw/DXF Tools Professional. If I make a 100% custom design, I export the cdr into V Crave Pro, then export to eps using V Carve Pro, import the resultant eps into Corel Draw then out to dfx via CorelDraw/DXF Tools Professional. In addition to designing, fabricating,and finishing custom metal art, I also sell custom DXF files from time to time and I have to have them "just work" first time on 99% of the CAD/CAM software out there. And when I do sell custom files to other CNC users, I send them several formats :CDR,AI,EPS,DXF..........and you hit on the head...buying low cost design files are ragged and edgy.... Most of these cheapie files are done using simple software tracing, with no inspection/node cleanup.....and the resulting metal pieces cut with cheapie type files are destined to be "future Yard Sale" items rather than being a treasure to the owner...so I may have stepped on some toes but the truth is what is

tcaudle also wrote :You have to learn to use the drawing tools and to be able to hand trace a bitmap (photo, scan. internet image) and not depend on autotrace tools that only work well on high contrast, high resolution images with low detail.

That right there is the single most valuable thing anyone can learn if they want to be profitable...I would add that you have to learn to hand trace QUICKLY....unless your doing it as a hobby that is

tcaudle wrote : Key to that was spending as little time in front of the computer and more at the plasma table.

Thanks tcaudel for your post!!

Marty

[motoguy]

Question...I've got CorelDraw and use Sheetcam on my CandCNC controlled system. Sheetcam imports svg drawings...is there any "loss" of any type in doing that? Would there be any reason I'd want to use the DXFTools for my use?

Also, I took the file the OP posted (Dad's Shed), and imported into Sheetcam. Sure enough, it looks just like his (chamfered, etc). Open the same DXF in Solidworks, and it looks great. So, is it not -completely- a Corel export issue? If it was, it would seem that the dxf would open the same in SW as it does in Sheetcam.

Exporting the DXF from Solidworks looks better, but there are about a billion nodes in the drawing...

Solidworks DXF snip.JPG (58.57 KiB) Viewed 2756 times

Solidworks DXF snip.JPG (58.57 KiB) Viewed 2756 times

[Les Newell]

The dxf issue is fixed in the current development version and will be fixed in the next stable release. I generally recommend SVG for Corel.