jagged arcs

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Rob Davis
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jagged arcs

Post by Rob Davis »

I had a customer send me his lettering files. He is an architect and is using some modified font instead of pre-loaded one so he sent them in Autocad file, I converted them in Mastercam and went to cut them. The arcs are now a lot of jagged straight sections instead of a smooth arc. Do I need to use NURBS feature? Should I redraw them with my own arcs? I don't really want to redo all of these but I can't send them as jagged letters either. Since these letters are 14" tall, they really show the arcs. Plus they cut slowly since not one big arc but lots of lines.
Any help is appreciated.
Thx.
Brad McIntosh
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Re: jagged arcs

Post by Brad McIntosh »

Rab,

Anytime you have a spline (nurb or parametric) in Mastercam and try and machine it directly, it will usually linearize it using a default tolerance that is set up for your system. What I have always done is to break the splines into tangential lines and arcs. You do that in the recent versions by:

1. Edit -> "Trim/Break" -> "Break Many Pieces"
2. Select you splines.
3. Set your Tolerance (aka chord height) to something appropriate. Depends on how exact you need things.
4. Make sure you have the "Curves" option selected/pushed in. I also usually select "Delete" so that the original splines are not in m way - unless I will make a effort to move the splines to another level for possibly use or reference later.

At this point you wee see where your splines will be "broken". Straight sections may be LINES, while the other segments will be tangential. In all cases each entity will flow tangentially from one to the next.

5. Once you are happy with the "look", click the "Apply" or "Ok" buttons.

Now you can define/apply your tool paths and the output will be "fluid".

Hope this helps...


Hope this helps.
Brad McIntosh
CNC Automation

Home: http://www.cncautomation.com
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Rob Davis
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Re: jagged arcs

Post by Rob Davis »

Thanks Brad. Tried on a couple letters and look good. Will give it a try on all of it this weekend.
Daniel Odom
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Re: jagged arcs

Post by Daniel Odom »

In Draftsight and Autocad you can explode all the text into individual lines. Once they're sploded you can select a set of connected lines that you think should be arcs then pedit them into on polyline and then pedit again this time choose the fit option and it (the polyline) should now be made of arcs. I Wouldn't want to do a whole of letters this way but it would work for a simple sign.
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