[Bug] Axial vs radial finishing pass contour

[fmw626]

The finishing contour is only calculated radially (X) and not axially (Y), which results in a poor finish for face features. I do not know what fixing this behavior would imply in terms of programming, if it is an easy fix or a huge can of worms.

Note that the finishing pass lines only offset to the roughing passes on X and not Y:

Here is a real world example:

;FMW TEST PAWN

STOCK D20
TOOL ANG R0.4 L11.1 A20.5 NA35
; see https://docs.google.com/spreadsheets/d/1Tj3v0c-DxfOColeAaKtqCuPuzpS3YvOxvTCyOrsoGRw/edit?usp=sharing

DEPTH CUT0.4 FINISH0.2; default depth of cut is 0.5mm
FEED MOVE100 PASS15 PART3 ; speeds mm/min

L0.5
L4 DS0 DE9 CONV
L4 DS9 DE0 CONV
L1 DS4 DE10
L0.5 D10
L1.26 DS10 DE7
L4 DS7 DE7.7
L3.8 DS7.7 DE16 CONC
L1 D16
L1.8 DS16 DE19.6 CONV
L4 D19.6

in this video you can see that during the finishing pass the tool doesn't engage for face features:

20240123_FMWA74_5472.mp4

[kachurovskiy]

@fmw626 thanks a lot for the detailed report. I'll try to reproduce myself but for now I noticed something really strange:

The finish layer on both top and bottom side of the sphere is the same but the resulting finish is different - in fact, top part of the sphere isn't finished at all. Looks like there's a backlash problem on at least one of the lathe axes? Do you get to the same point when moving an axis by X forward-then-reverse when starting with backlash taken out? Honestly not sure what could cause this behavior.

[kachurovskiy]

Here's a slightly modified (only tool, depth, feed) version I used:

STOCK D20
TOOL ANG R0.4 L11.6 A32.5 NA55
DEPTH CUT1 FINISH0.2
FEED MOVE300

L0.5
L4 DS0 DE9 CONV
L4 DS9 DE0 CONV
L1 DS4 DE10
L0.5 D10
L1.26 DS10 DE7
L4 DS7 DE7.7
L3.8 DS7.7 DE16 CONC
L1 D16
L1.8 DS16 DE19.6 CONV
L3

PXL_20240126_195728384.2-h264.mp4

It wasn't perfect but the entire part was finished - not just half of it like in your case. Let's think what might cause that...