path 3d pocket is doing some wrong

[wbeppler]

when i want to mill that part at pic 1 by using "path 3d pocket" sometimes it works fine, see pic 3

fc_gerade.png (175.56 KiB) Viewed 1216 times

, but at pic 2 and 3 you can see that the cutter goes in one case ok and in one case goes parallel down what is not ok,, at the other half-circle it goes ok and sometime if i only select one face to base geometery it goes parallel down and when i select a second face to base geometry it fails. i made yesterday one "path 3d pocket" all was ok, today always one half-circle allways goes parallel in z-direction. i made no modify at my part ! what is the problem ?
a 2nd problem is that the toolpath always end at the selected face, but all 4 faces are one thing, so when i mill i allways have a wall between thes faces. that's not nice, but the first problem is really a problem !
thanks for help

[herbk]

i can confirm that there go's something wrong:

oval.jpg (56.45 KiB) Viewed 1210 times

It's made with:

OS: "openSUSE Leap 42.3"
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.13516 (Git) AppImage
Build type: None
Branch: master
Hash: 7101d9a89d49ed718d42611a81f1097b723e5ad2
Python version: 2.7.6
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: German/Germany (de_DE)

Btw: Why the path is made in 4 parts? - it is one pocket only, made with one cut.

[chrisb]

As for the second issue: There are four faces so currently there are four separate paths. As for the first problem: it might be some internal coplanar problem, could you try to turn your object by a few or even by 90° and tell what happens?

[wbeppler]

hello,
today i tryed again...
first: it is not a oval ! there are 2 half circle and 2 straight
second: i rotated -90 degree because so my machine is build and when i select the operation zigzag it works (terrible) but when i select spiral fc crashes
third: i used a older construction-file and in the original wrong position it works using spiral but -90 degree in Z it crashes

another problem is the accurancy, if i select a tool 6mm ball it generates in my grove at the last layer 2 paths and no last in the middle, is there a parameter i dont know ?

today i learned a lot, thanks the crashes and this forum, thanks to all !

OS: Ubuntu 16.04.4 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.13588 (Git)
Build type: None
Branch: master
Hash: 1e2b9758cc7f6872da018ee71983a82499866508
Python version: 2.7.12
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: German/Germany (de_DE)

[chrisb]

I can contribute only to the last point: currently the Path workbench does not respect different tool shapes. The toolpath is alway calculated for an end mill.

[wbeppler]

thanks for info,
what do you mean with "end mill" only flat one ? no ball ?

[chrisb]

what do you mean with "end mill" only flat one ? no ball ?

Only flat; that's what I thought to be an end mill, but english is not my native language, so misunderstandigs are likely.

[wbeppler]

hi,
now i tryed to another way to get my groove, i cutted it flat and use path-pocket but insert a 8mm ball cutter to get the roundings. but now fc makes 6 interrupts in my path. i tryed with lower tolerance and at last i insert a 7,5 mm cutter but the interrupts are the same.
it looks realy strange at the passage from curve to straight, at 2 positions it works, at other 2 not.

has anyone a idea ?
thanks

tool_75_bad.png (211.43 KiB) Viewed 1105 times

[sliptonic]

It's not ideal, but you could try selecting the outer edges of the oval loop and then do an edge profile. Edge profiling will work on the edges as a loop rather than the individual faces.

[mlampert]

Looks like your tool has the same width as the slot - what you see are probably rounding issues where the slot ends up being smaller than the tool.