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Fusion 360 - cutting too slow

I am just starting to use Fusion 360 for CAM, and having a problem with it cutting too slow. It looks like it is trying to make very small movements around curved areas, only moving ~2 in/min. This makes for very jerky movements and nearly pausing, probably because the movements are too short and it has trouble overcoming the static friction. On long straight cuts it gets up to the programmed 30 in/min, though they are not very straight.

I assumed the parameter I needed to adjust was the Tolerance. On my first cut I left it at the default 0.004". On my second cut I increased this to 0.05". Both had about the same results.

I have had much better results from Makercam and Easel - lines are very straight, curved areas cut nearly as fast as straight areas, etc.

What should I look at doing different?

This is what I am trying to cut. Simple 5"x5"x0.75" block with one pocket and one contour cut.

Cut 1 on the left, cut 2 on the right.
b block cut picture

Fusion 360 file is below, if anyone wants to take a closer look.
B test block v3.f3d (189.6 KB)

are you using the maslow post processor?

it would make a huge difference if fusion is outputting lots of short line
segments rather than arcs

Yes, using the Maslow post processor.

Is there anything in the post processor setup needed besides selecting the Maslow post processor file?

there shouldn’t be.

in your model, do you radius corners? or is it slow in the long curved parts
(and are those curves circle arcs or some other curved shape)

David Lang

I used the text object to make the B.

I did not put radii in the corners of the box.

It is slow cutting both the small and large radius parts around the B.

As you can tell by the gaps in my post, the time I can get to my hobbies is quite infrequent.

Today I made a new block of the same size, but with circles/semicircles of different radii, instead of a letter. This cut much faster, no hesitation or stalling, so maybe the issue is with how Fusion 360 works with text.

Though it cut faster, the quality is not good, such as the defects around the inside corners. Not sure what the issue is there. Haven’t had problems with that when using Makercam or Easel.


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Today I finished my “big cut”, that I was hoping to learn enough from these test blocks to optimize. Most of it cut well, though it still hesitated and went slow around the curved letters like S, C, D. This file was designed in Inventor then imported to Fusion 360.

This video shows cutting around the top of the letter C. Any ideas how to improve this? Below is a video, the fusion 360 file, and the G code.

RCD pocket -25 with finish pass.nc (706.5 KB)

rough cut designs final v1.f3d (946.7 KB)

Is this with the buffering of gcode enabled? That might help process those lines of code faster

I did not, but will give it a try. Any disadvantages to running with that setting on smaller cuts?

We have it disabled by default because on a spotty USB connection it was leading to glitches and miss cuts. For 90% of people it is a better option, but 10% of the time it was causing issues

Fonts often have have very detailed paths when converted by 3D programs. One thing that should work is using tool path “smoothing”. This is set per tool operation (e.g. 2D Contour) and you specify precision (0.05mm/0.002in) This often greatly reduces the complexity of gcode with no loss in precision. I had some projects reduced to 1/3 filesize!

You can probably do some sort of path simplification in the 3d model too but I do not have fusion on this comp right now and cannot remember how.

edit: Changes “optimization” to “smoothing”

Is this the setting you were thinking? I changed this from the default 0.004" to 0.05". Though maybe I should reduce this further?

Yeah that looks like it. I use 0.002" which is the max that Malsow can do and it already made a huge difference. 0.05" may be too much.

I thought 0.05” was too much, but wanted thought setting so high would show if there was an impact (see year blocks above, did not seem to impact). 0.002” sounds more than reasonable.

Without smoothing/tolerance Fusion360 outputs coordinates with something like 8 decimal places which is complete overkill for Maslow. You will not visibly see the changes in any program but will see it in the gcode file and might be able to measure it in the cut piece.

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