2D contour smoothness help

[Anonymous]

Broad title, sorry.

I've encountered a problem and I'm not sure how to fix it. 

The part I've programmed for is elliptical, and needs a nice finish on the outside before polishing.

When I create a 2D contour, with or without smoothing I get code with g1's and g2's. When run in the machine creates these flat sections that are about 1/16 apart. Same settings in MCAM with line/arc filter, code gets created with only g1 and small movements as you can see by the second post, which when ran in the machine was quite smooth.

Is there a way to get my post to look like MCAM?

(5/8" ENDMILL - FINISH)
N12 S650 M3
N14 G54
N16 G187 P3
N18 G0 X-2.0288 Y-0.125
N20 G43 Z1. H2
N22 M8
N24 G0 Z0.1
N26 G1 Z0.0394 F120.
N28 Z-3.175
N30 G41 X-1.9038 Y-0.1563 D2 F6.
N32 G3 X-1.7475 Y0. I0. J0.1563
N34 G1 Y0.0024
N36 Y0.0048
N38 X-1.7474 Y0.0073
N40 X-1.7459 Y0.0731
N42 G2 X-1.7452 Y0.0876 I0.3124 J-0.0073
N44 G1 X-1.7406 Y0.1533
N46 G2 X-1.7393 Y0.1677 I0.3117 J-0.0218
N48 G1 X-1.7316 Y0.2331
N50 G2 X-1.7296 Y0.2475 I0.3104 J-0.0363
N52 G1 X-1.7189 Y0.3124
...

N100 G00 G40 G49 G80 G90
N110 T2 M06 (5/8 FLAT ENDMILL)
N120 G00 G54 X-2.2484 Y-.2478 S650 M03
N130 G43 H2 Z1.
N140 M08
N150 Z.1
N160 G01 Z-3.17 F120.
N170 G41 D2 X-1.9984 Y-.2487 F6.
N180 G03 X-1.7475 Y.0004 I.0009 J.25
N190 G01 Y.0124
N200 X-1.7473 Y.0247
N210 X-1.7471 Y.0371
N220 X-1.7468 Y.0494
N230 X-1.7464 Y.0617
N240 X-1.7459 Y.0741
...

[HughesTooling]

This is a very old bug that doesn't seem like it's going to get fixed. The problem is Fusion does corner rounding before it does smoothing\arc fitting. An easy example to understand is if you have a 90° corner and use a 10mm cutter the toolpath will have a 5mm corner radius. What's happening in your example is Fusion's generating hundreds of short line moves and adding a radius equivalent to the radius of the cutter and this totally kills arc fitting.

You will get a better finish if you use 3d contour and set the stepdown to the step needed to get one cut.

Mark

[HughesTooling · Accepted solution]

See attached file for example using 3d contour and tolerances. I find a smoothing tolerance the 1.5 to 10 times bigger than tolerance works best.

Mark

[Anonymous]

That is an unfortunate bug to be around still...

Thank you for your solution/answer, I'll try it next time I get another elliptical part.

[seth.madore]

---

@HughesTooling wrote:

This is a very old bug that doesn't seem like it's going to get fixed. 

---

It will get fixed, it just is sitting on the low end of the priority stack at the moment. It's down to how Smoothing is handled. Right now, it's handled in the UI, and the team is looking into how they can get it handled in the kernel.

[MoshiurRashid]

I've faced the same problem. Few days later, I came to know it is because of a bug. It's not fixed yet.

[vilts]

I have somewhat similar issue - 2D contour and Trace do linear moves, instead of arcs. But the issue appears when round "thing" is machined at an angle. Lets say a cylinder, and machining angle is not exactly 90 to the top face (so essentially an ellipse in this case). Smoothing doesn't do anything, no matter the tolerance and the machinable contour is round.

I found this out just today when I machined parts for customer and the round corners were all faceted. Not nice at all.

The attached f3d shows the issue well.

Is this the same bug/issue, or a different one?