Idea - Helper Segments for corner clearance

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MRx
Posts: 319
Joined: Wed Jul 08, 2020 5:59 am
Location: Tainan / Taiwan

Idea - Helper Segments for corner clearance

Post by MRx »

Hi,

I'm cutting the contours of my object with a relatively big endmill, that leaves the issue that corners won't be as accurate as they should be.
Instead of generating a complete contour again with a smaller endmill I thought about generating helper segments, picking points on the object, generating a 2d face and running eg. an adaptive algorithm.
Bgdhey.png
Bgdhey.png (12.06 KiB) Viewed 2369 times
or does anyone have a better idea?

Code: Select all

def createFaceFromPoints(pts):
     start=FreeCAD.Vector(pts[0][0], pts[0][1], 0)
     begin=start
     segments=[]
     for i in pts[1:]:
           beginv=FreeCAD.Vector(begin[0], begin[1], 0)
           endv=FreeCAD.Vector(i[0], i[1], 0)
           segments.append(Part.Edge(Part.LineSegment(beginv, endv)))
           begin=endv
     segments.append(Part.Edge(Part.LineSegment(begin, start)))
     return segments
     
f=Part.Face(Part.Wire(createFaceFromPoints(s.PickedPoints)))
Part.show(f)
MRx
Posts: 319
Joined: Wed Jul 08, 2020 5:59 am
Location: Tainan / Taiwan

Re: Idea - Helper Segments for corner clearance

Post by MRx »

okay since there's no reply here, Romero in the chat gave me a good hint -- use the Draft workbench.

The rest I figured out myself:
1. lock the working plane:
TMFQI4.png
TMFQI4.png (2.22 KiB) Viewed 1881 times

2. set up the snapping:
pYMLJz.png
pYMLJz.png (19.58 KiB) Viewed 1881 times
3. start drawing lines or polylines.
There are some snapping issues sometimes it seems but that's a very good strategy to add extra surfaces for milling.
chrisb
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Re: Idea - Helper Segments for corner clearance

Post by chrisb »

You should keep in mind that Draft snaps are not parametric. If you make changes to previous steps, the helpers will not follow.
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herbk
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Re: Idea - Helper Segments for corner clearance

Post by herbk »

Hi,
MRx wrote: Tue Nov 30, 2021 4:47 am I'm cutting the contours of my object with a relatively big endmill, that leaves the issue that corners won't be as accurate as they should be.
i don't understand the problem, because i don't have probs with the accuracy of corners, no matter of the tool size...
Gruß Herbert
MRx
Posts: 319
Joined: Wed Jul 08, 2020 5:59 am
Location: Tainan / Taiwan

Re: Idea - Helper Segments for corner clearance

Post by MRx »

How do you machine 90° inside angles with a 16mm endmill? :-)
I use to use the biggest endmill for removing the main area and the smallest ones for the smallest parts to mill.

It's also called rest machining, rest milling.
chrisb
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Re: Idea - Helper Segments for corner clearance

Post by chrisb »

herbk wrote: Tue Dec 28, 2021 8:21 am i don't understand the problem, because i don't have probs with the accuracy of corners, no matter of the tool size...
I think it's not the accuracy of the milling path. The problem is the tool size in the corners, where a big tool leaves more unwanted material. The alternative to mill everything with the smallest tool is usually no option either. Creating another pocket operation with the smaller tool results in useless paths. Using a profile could be too hard in the corners if the difference in tool size between the first and the second pass is too big. Furthermore, if the distance between corners is big, rapid moves between them can be desirable.
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