TurboCAD Mac Forum

TurboCAD Mac Categories => General Discussion => Topic started by: mjwicker on July 30, 2020, 10:53:19 AM

Title: Curve approximation setting or adjustment?
Post by: mjwicker on July 30, 2020, 10:53:19 AM
Hi guys,
I'm using V11 TurboMac Pro, if you want more details I can screenshot the version and OS info.

I've come across a problem, not often but situationally where the approximation of circles and curves greater than maybe 8in depending on tolerance and definitely larger than 16in is a problem. It seems as though there is a more accurate approximation buried in the background of TurboCAD based upon where the pixels are and where the snap goes when I connect lines to a curve when zoomed in. But when I export to .dwg/.dxf, it only saves the pixels not the background information and that hurts the accuracy of my drawings especially when using them for a CnC where it ends up cutting an equal lateral polygon instead of a circle when I wanted a circle.

I have attached a series of increasingly small circles showing how zooming into all of them shows the approximation techniques.

Is there a way to adjust the accuracy of the circles I make?

I'm aware of the "Simplify Curves" button and while it seems to increase the number of sides in a drawing (and nothing out of a drawing for some reason), it's not by much and doesn't help. I'm poking around a little and hope to find a way to increase the polygon sides of an arc or circle by an order of magnitude.
Title: Re: Curve approximation setting or adjustment?
Post by: mitchb on July 31, 2020, 04:09:09 AM
I think the issue you are having has to do with resolution. Circles are represented by polylines, the higher the resolution the more lines and the smoother the circle looks. See the difference in screenshot 1. See screenshot 2 and 3 for different ways to set the resolution. The Edit menu can also be used.

Enjoy
Mitch
Title: Re: Curve approximation setting or adjustment?
Post by: mjwicker on July 31, 2020, 09:46:29 AM
Thanks Mitch, always insightful.

That helps a little. It was already defaulted to "Very Fine", with "Super Fine" as the only higher resolution setting.

Does that mean the ability to set poly lines so they are not visible to the naked eye for large radius features (say R>16" for example) isn't doable yet?
Title: Re: Curve approximation setting or adjustment?
Post by: mjwicker on July 31, 2020, 10:13:48 AM
Okay, so I have a follow up question.

It appears from the wording here that TurboCAD is programing Arcs using that Curve Angle radially locate set points around the center and drawing Polylines through those set points.

Is this setting what it looks like, that I can set this to a very small angle for larger circles, especially when I need it for a cut file? If this does work the way I suspect, do I need to account for the Facet Angle as well somehow?
Title: Re: Curve approximation setting or adjustment?
Post by: mitchb on July 31, 2020, 10:24:26 PM
Resolution for curves is set with Curve Angle, Facet Angle is used with surfaces and solids. You didn't mention which version of dwg/dxf you are exporting to. The export default is set to R12 an old standard, use a newer version if you can.

The screenshot I'm including is an excerpt from a book by Tim Olson. ViaCAD tips and tricks available from masterviacad.com (http://masterviacad.com) a valuable resource if you are serious about using this program.

Enjoy
Mitch