@tig said:

Scaling up to avoid faceting and other small visible geometry issues is a well known workaround.
The guys who developed Flowify devised and use this method to model classical columns in the minutest detail - they are miles high in the SKP !

Because you are incorporating complex 3d geometry into the form then the suggested 3d-gives-true-circles in a CAD file export etc is of no use - it's only useful if the geometry is 'flat' - e.g. for 2d CNC cutting...

Sorry to beat this dead horse but I am still trying to establish a go forward plan.

1: Is there another CAD program that could smooth Sketchup 3-D shapes for use with a CNC?

2: I have not used any other CAD programs so if Sketchup can not provide what I want what are some easily learned CAD programs that will provide a smooth complex 3-D surface?

Thank you for your reply's.

@tig said:

This was really aimed at arcs/circles used to extrude parts into 3d forms.
For example exported into 3d CAD files.
Remember that a 2d CAD file export will produce faceted arcs/circles whatever you do.
If you want to make fully smooth arc/circles then you can always model as 2d [to avoid any extrusions locking the form], then export that as a 3d CAD file.
A 3d CAD file [in contrast to 2d] uses true arcs/circles, without any faceting.

So, if you are looking to export simple 2d CNC cutting profiles, then consider using them in 3d CAD file exports, to fully smooth them...

Other then sometimes lines will intersect at different locations based on how many segments are utilized. I have attached a vent handle that I modeled with plans to cut out of billet aluminum. I am preparing models prior to purchasing a machine. I modeled the handle 100,000,000 times larger than needed to eliminate errors from Sketchup. It is in inches.

My plan is to model and cut dress up items for show vehicles so my final product has to be cut perfect.

I have spent so much time with sketchup that I do not want to use a different CAD program. Hopefully the CNC can compensate and provide me with a smooth final product.

Vent handle Dec 6-18.skp

I want to start running a CNC mill based on my sketchup drawings. I am going to make aluminum parts for my truck and then market them once I have them correct.

Sketchup is all I have ever used but never in a way where my drawing will directly transfer to a machine for cutting. My main worry is how many segments to draw to have a nice final CNC product.

When looking for a circle segment rule of thumb I came across this post and have applied some of the math into a spreadsheet to understand what my limitations might be.

From your post I have come up with this to complete calculations in excel

degree 1 (d1) = 360 degrees / Segment # (S#)
degree 2 (d2) = d1 / 2
Radius of circle (r) = Perpendicular length from segment midpoint to circle center (PL) + Versine (TOL)
PL=r-TOL
Cos(d2)=PL/r
Cos(d1/2) =((r-TOL)/r)
Cos(360/(2*S#))=(1-(TOL/r))
Cos(180/S#)=(1-(TOL/r))
(180/S#)=ACos(1-(TOL/r))
S#=180/ACos(1-(TOL/r))
r=TOL/(1-(Cos(180/S#)))

For excel:
S#=(180/(DEGREES(ACOS((1-(TOL/r))))))
r=(TOL/(1-(COS(RADIANS((180/S#))))))

For drawing small parts accurately I typically scale up 1 million to 100 million times to make the number entry without decimals. This totally eliminates the failures of sketchup with small dimensions.

What I find is sketchup starts to get slow or crashes when I use large numbers of segments. What I have found is past 100 segments some extensions do not want to work correctly.

Based on a limit of 100 segments and a Versine tolerance of 0.001 inches that will limit me to a radius of 2 inches. Sketchup will allow 999 segments but I doubt the program will function.

Now to my question:

Is there an intermediate program that I can import my low segmented circle sketchup model into to ready the model for printing or cutting smooth circles. This would allow me to continue to use sketchup instead of learning another CAD program to facilitate my CNC work.

PipeDraft

(www.pipedraft.com)

PipeDraft
A SketchUpTM plug-in for pipe drafting.

PipeDraft is a 3D piping plug-in for SketchUp that's quick, fun, and easy to use. Best of all it's specification-driven to deliver component fittings from piping catalogs in the Cloud.

About PipeDraft
PipeDraft is a cloud-based and spec-driven 3D piping plug-in for SketchUp(TM). It is designed to be quick, fun, and easy to use. The usual time-consuming complexities of managing and sharing piping specs and catalogs is hosted transparently as a back-end web service, effectively facilitating an administration-less user environment.

PipeDraft contains proprietary and confidential content owned by OnApplied LLC and third party licensors. No content may be disclosed, decompiled, reused, or distributed without written permission from OnApplied LLC.
About OnApplied
OnApplied LLC is an IT consulting and technology development business that helps customers achieve their business objectives through sustainable deployment of innovative IT solutions. OnApplied was founded in 2000 and is privately held.
Tradename Ownership

Adobe and Adobe Acrobat are trademarks of Adobe Systems Inc.
Google App Engine is owned by Google Inc.
PipeDraft is owned by OnApplied LLC.
Python is a trademark of the Python Software Foundation.
Ruby is a copyright of Yukihiro "Matz" Matsumoto.
SketchUp is a trademark of Trimble Navigation Limited.

All other third party products are trademarked or registered trademarks of their respective owners.

The susolid free 1_1 version caused massive bug splats on my HP laptop. Windows 7, separate video card, i7 processor and lots of ram. I had to go through all my plugins to locate this one as the culprit. Next time I will load one plugin at a time and utilize sketchup to see if the latest plugin addition is not compatible. Instead I loaded plugins like crazy only to have this one give me bugsplats. Hope someone avoids the bug hunt like I had.