2D contour: Stepover and smoothing deviation

[Anonymous]

Hi, 

I'm trying to understand smoothing deviation in 2D contour. Did some research but found nothing related to my doubts. 

From what I understand, smoothing deviation (finishing smoothing deviation to be specific) is the maximum radius of smoothing toolpath added to sharp corners. To illustrate this, I've modelled a 20*20*5mm block with a 2.5mm deep hole with fillet 0, 1, 2, 3mm starting from the bottom, going anticlockwise. I'm using a 2mm diameter tool.

Then I add 3 finishing passes with 0.2mm stepover.

Here's what I get when I add 0mm smoothing deviation: 

Notice the corners at the right do not have circular toolpath, which makes sense for me. 

Then, 0.05mm smoothing deviation: 

Corners at the right start to have I believe 0.05mm radius? Also, to clear some doubts, do the final pass not have a radius due to the size of the tool? 

Then 2mm smoothing deviation:

This is where I get confused, instead of generating toolpath with 2mm corner radius and maintaining the same RDOC, the innermost and middle toolpath seems to have shifted out, taking more cut than they are supposed to.  The same goes to when I'm trying to machine one of the outer corners of the same model even if there aren't any sharp corners to be smoothed? 

Thanks.

[Mattxer]

The final pass dosnt have any radius because you probably dont have finish smoothing deviation set to anything. They are two separate settings under 2D Contour.

Smoothing Deviation

The maximum amount of smoothing applied to the roughing passes. Use this parameter to avoid sharp corners in the toolpath.

Finishing Smoothing Deviation

The maximum amount of smoothing applied to the finishing passes. Use this parameter to avoid sharp corners in the toolpath. Setting this parameter leaves more stock than requested at the contour corners.

Source: http://help.autodesk.com/view/fusion360/ENU/?guid=GUID75B6821B-DE26-4E3B-AF10-4A54131CD9E4

[Anonymous]

Thanks for the reply. Did you check the file I have shared? I did use Finishing Smoothing Deviation, I did not use any Roughing Passes. 

I've read through the link you gave me. The explanation I'm looking for is not there, perhaps I'm missing something?

Cheng

[Mattxer]

I'm not entirely sure why you would have smoothing on for a straight line contour. As for the pocket I found that if you set a minimum cutting radius that last pass sharp corner goes away. I'm not sure what the use case of smoothing is if you can just set a minimum cutting radius.

[Anonymous]

I'm trying to understand how smoothing deviations work. Of course, I can work my way around to get my part done, utilizing minimum corner radius is a good way.

Cheng