Why facets??? Why?

[racingjas]

Hi guys,

while milling circles for example in surface finish contour my parts are coming out with facets. It happens as well on non circular features. 

How the heck do I stop this? 

Thx in advance and I appreciate all the help. 

[huskermcdoogle]

look at your filter settings and tolerances in the tool path, likely you are way to loose and aren't filtering the code

[Leon82]

Put the total tolerance at .0001

 

And I slid the left hand slider all the way to the right. This posted all my Ellipsis as arcs

[Reko]

1 hour ago, racingjas said:

...while milling circles for example...

Is your geometry an arc or a spline?

Selecting a spline will produce faceting and poor finishes.

[Metallic]

I have also wondered if Chord Deviation will cause this? I set mine to 0.0001" instead of the default 0.0005" in the control definition and at the machine

[Guest]

You don't say which version but...

1st, make sure everything that can be an arc is an arc......in 2018 under Wireframe >> Refit Spline >> Choose the Simplify command....that will alter splines that are true arcs and/or straight lines into line/are geometry....

2nd, if you still have splines.....the Arc Filter in the toolpath....tighten the values WAY up, then set the G17 create arcs radio box.... 

 

Splines can happen for several reasons

A bad translation from another CAD software...

an iges file

a file that has an ever so slight skew to it

Those are just few reason why they can happen

Edited March 22, 2018 by Guest

[esler1]

Try Backplotting the toolpath, then save as geometry to a new level. Then drive your toolpath with that.

[mike93]

If someone exports out of solid works with a large tolerances, that is the shape of your part, if you machine to the model it will have facets.

 

It takes to long with that small tolerances the designer says!

[pullo]

13 hours ago, racingjas said:

Hi guys,

while milling circles for example in surface finish contour my parts are coming out with facets. It happens as well on non circular features. 

How the heck do I stop this? 

Thx in advance and I appreciate all the help. 

Some precision here ,  You could only mean here "milling surfaces which I think are circular" , not "milling circles".  A circle is a 2d wireframe entity  and can be machined using 

a profile toolpath ,like helical and you will get circular or helical interpolation output.  I at least could try to give you a better diagnose if you could post the geometry file..

Some pointers without seeing the patient:

1.  you might thing it's round , but it's not . Please remember that an arc is a SPECIAL CASE OF AN ELLIPSE. 

2. you might have linarc$ set 1 for some reason  in your post .

Gracjan

[mayday]

"Splines can happen for several reasons"

mastercam is the main reason

[huskermcdoogle]

3 hours ago, mayday said:

"Splines can happen for several reasons"

mastercam is the main reason

I disagree, it's the fault of the CAD operator.  Hardly ever fails that someone was using Creo, and doesn't have a clue how to export a usable surface model....

[pullo]

"mastercam is the main reason"

There used to be a site , "why  you should not use  Mastercam" , but it's been discontinued

Gracjan