Cutting smooth arcs and circles


New Member
I Need help again. How does one improve the smoothnees of a large circle or arc with a cnc router. Is there a program that would import my .dxf file and improve it?

Thanks. :help:

Dennis Raap

New Member
I found that it has a lot to do with what format the files are when importing to the machining software.

What software are you using?
I heard that same thing. I had a old sign guy that said to me that he hated using .dxf files bacause of arcs but that was back in trhe 80's when he use to send artwork out to a subcontractor for raised lettering. He told me he prefers .ai files better . He told me that in .dxf files they lose points. My cnc router company says that the .dxf file has been improved since then. But the other day I'm cutting out lettering in 1/2" acrylic and the curves suck. Not that bad but I couldn't flame polish without really having to sand for a while. The curves have little ridges in them, almost like a sproket but small. I need to do some more letters and try exporting with .ai and import with my cnc control software and see what that does. I think I need to take a pic of that lettering and post. Matter of fact I will. Anyone having this same problem and know the answer?

Dennis Raap

New Member
I think the new dxf may work better but the problem is that some times the software that is being used for the export will use an older version of dxf or ai or what ever I am having a problem with Flexisign Pro right now when I export to ai format and try to open in Coreldraw 12 the program crashes.


New Member
I'm using ANA Design art pro and exporting dxf format to Enroute. I'll try exporting ai files and see if that helps. Thanks for the input.
I usually use flexi also, exporting out using .dxf I'm going to use Sign Lab and save the file as a part file. I hear Sign Lab is one of the best programs to use beside artcam pro, I have both but never used. I better start to expand my horizons

Fred Weiss

Merchant Member
If you get a file with too many nodes try using the Simplify Path command in Adobe Illustrator. Set the Curve Precision slider to 100% and the Angle Threshhold to 180 degrees. Turn on Preview and Show Original to evaluate the result before finalizing it.

Screen shots below.


  • Simplify Path Dialog.jpg
    Simplify Path Dialog.jpg
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  • SimpPath Before After.jpg
    SimpPath Before After.jpg
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  • Simplify Points Off.jpg
    Simplify Points Off.jpg
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Dennis Raap

New Member
If you are using Flexi 7.5 and Enroute you can send a file directly to Enroute if it comes in to Enroute all broke apart select every thing then go to Transform select Merge this will put every thing back together.
I'm not getting that many points in my artwork, it's more like the "after" but as I export it to my control software I will need to check. I have a buddy who had the same problem and all he had to do was update his cnc control software and it did it for him. But not with me, and we have the same machine. I'm even told certain fonts will do this too.


New Member

That sample looks aweful familiar.

I had the same problem with cnc plasma cutter a year ago. The problem resulted from the resolution the dxf was saved at.

On another note, Fred is doing a little project for me and I unknowingly sent him a file bogged down in nodes. This was a result of converting a stroke to an object, something I'll try to avoid in the futere.


New Member
check g-code

Hi Stonehouse,
I'm new to this site; I have a small woodshop that specializes in CNC fabrication and design; so I'm not really a sign maker. Anyway, your problem with your arcs may be in the g-code; check that your arcs are being cut using g02 or g03 commands. These define the arc mathmaticly instead of as a series of points. You should get a near perfect circle/arc using g02/g03.
Jon Blanchard
Actaeon Custom Woodworks, LLC

Bobby H

Normally G-Code language should not have any problem making true curves, arcs, etc.

One should make sure the DXF format file being brought into EnRoute is one of the polylines variety featuring true arcs. Some forms of DXF will simulate arcs by using lots and lots of short line segments.

And then there's the actual artwork creation itself. CorelDRAW can be a culprit in this due to the way it has rendered its contour effect in the past. Basically you would get something similar to what old versions of DXF did, thousands of control points joining many line segments to simulate a curve rather than making a real curve. Supposedly CorelDRAW X3 has put some work into solving that problem. Adobe Illustrator is excellent at creating outline effects and such with a minimal number of nodes. Only the latest versions of Freehand can contend with it. But Freehand is a soon to be dead program.


New Member
It doesn't really matter if the dxf has a smooth arc or not. You can smooth it out by adjusting the curve tolerance in your CAM program. In the example that i've drawn fig1 is what you would like, fig2 is the dxf, the red line in fig2 is the curve tolerance.


  • Curve.jpg
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New Member
We use casmate then export file out as a dxf polyline this usally takes care of are problem with arcs.

Bobby H

You must be using some older computers in order to keep CASmate alive. We had to migrate to Flexi after the releases of Win98 SR2 and Win2000. CASmate 6.52 just wouldn't run on either worth a hoot.


New Member
from my experience running enroute, and flexi i have no problems. you can downsave to a flexi 6 and it will import into most any cadd software. I have seen tons of problems when a customer sends me illustrator files, i don't know what it is but there are many times when i go to toolpath the design and theres ton's of loops and bad arcs, so i just clean them up with the arc tool in flexi.