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Fusion 360 or Machine Problem

Message 1 of 11
624 Views, 10 Replies

Fusion 360 or Machine Problem

I am new to machining and Fusion.  I have machined a total of 9 parts since converting a mill to CNC.  I am sometime challenged to figure out if a problem is a result of an issue with my machine or a programming mistake.


Upon completing the CNC conversion, I learned that the ball nuts were faulty. I had the X and Y professionally repaired. They now work great and have less than 1/2 thou backlash. The Z ball nut has about .004 of backlash that is currently being compensated for with backlash compensation. At some point this ball nut will have to be repaired, but this is a major endeavor. I decided to see what limitations this backlash imposes before taking apart the entire mill.


My latest challenge, there are gouge marks around the perimeter of the part created during the parallel tool path.  Please see below.   Do you think the issue is a result of an incorrect lead in radius?  Does this appear to be a programming error?  If not, I will look further at the mill for possible issues.


Fusion File:


Thanks... Richard



Message 2 of 11

Sorry... Here is the image I meant to upload.

Message 3 of 11



It almost definitely is your machine, but in saying that, there are some things we can do in Fusion that should help you out.


I've done a bit of a deep dive Video here on your part with a few tricks for getting better results:

Message 4 of 11

WOW... Ask for a penny.... Get a pound.  When I posted this issue, I was only expecting a quick comment pointing me towards Fusion or Machine.  Thanks so much for all your time and effort.  EXTREMELY HELPFUL!!!


The toolpaths for this part are not my ideas, but rather the result of following online lessons to learn CAM (Titans Of CNC Building Blocks, see link below).  I have no previous experience.  These classes are designed to train apprentice machinist to run professional equipment.  I have strictly followed the lessons modifying only the speeds and feeds for my mill.  One point worth noting is that the ballnose end mill used in their lesson was a 2 flute variety.  Thanks for sharing the knowledge of the 2 flute vs. multiple flute options.


Oddly enough, when I observed the problem at hand, I wondered if there was some way to extend the toolpath so the linking moves would not gouge the part.  I could not figure out how to do this.  Thanks for your assistance!


I spent some time implementing all your suggestions and plan on machining the part in the next day or so.  I think I am going to add -.01" Z to the tool height offset and try to run these toolpaths again.  If all looks good, then I can re-run the part from scratch.  I will post an image of the results.


Just a few quick questions:


1.  The original Parallel toolpath had the Additional Offset set to .05.  Could we have accomplished similar results by changing this value to for example .1 (see below)?


2.  Lastly is the neat app you used to calculate the proper stepover something that can be shared?


Again... Thanks so much for all your help.  At a minimum, you made my day!


Best... Richard








Message 5 of 11

So  the additional offset allows the tool center to extend past the boundary by that much, but it keeps following the model, so in this case the tool would drop down and start machining the chamfer, which isn't what we want in this case.

That's why we do the extended surface so the tool goes off the part completely, that way the leads are right off the part and there's less chance of marks showing up.


I prefer to use 0 additional offset and use the contact point boundary checkbox to get the tool contact point right to the edge.


As for sharing the app, the forum wont let me attach programs so ill have to find another way of providing access.



I've looked into the Titans stuff before to see what it was like(more looking at the aerospace academy stuff)


Its definitely a good starting point, but they don't really go into a lot of detail, but I suppose too much information could be overwhelming for a new user.

Message 6 of 11

Thanks for the explanation.  Looking forward to running this part with your ideas incorporated.


Again... I really appreciate all your efforts here!

Message 7 of 11

Hello Again,


I was just reviewing the file that I had modified and noticed that for some reason, my Parallel toolpath takes 31 minutes while yours takes only 23:26.  I do not see where mine is different than yours.  Probably not significant.  I will keep you posted.



Message 8 of 11

Its possible the values in the machining time calculation are different

feed scale.png


Your feed scale and rapid speed affect the time taken.(and toolchange time)


It more of a guideline anyway as its rarely accurate

Message 9 of 11

Hello Andrew,

As promised, here is the result of the Andrew Las tweaks to the CAM programming (see below)!!  This part came out quite nice.  The few remaining gouges are remnants from the previous approach.  They were not created from the revised tool paths (I dropped the Z-height of the tool and machined over the initial approach).  Thanks for all your time and effort.  Greatly appreciated.  


Again, I programmed this part by following the online tutorial Titans Of CNC Building Blocks.  It is the only  CAM course I have taken and so far, so good.  The course only includes machining the top of the part, but not how to machine the second operation for the back of the part.  I machined the soft jaws by creating a shape with a simpler profile and used the combine function to create the pocket in the soft jaws.  This process worked fine but I think I did something wrong with the setup for the final operation.  The problem is that the Simulation does not work properly.  The facing operation works fine but chamfering does not display properly.  If I wanted to perform additional operations on the back side of the part, it would not work correctly.  Is there something I need to change in the final setup?


Fusion File:


Thanks... Richard  















Message 10 of 11

Hi Richard

Sorry I have been away on holiday for a few days.


That's great that the part came out better.


I'm not 100% sure what the issue with your second setup is as it seems to work fine for me

But heres a few more tips:


Message 11 of 11

Thanks so much for the suggestions!    Just for clarification, I did not have any issues with the chamfers.  I was just trying to improve how the simulations look.  Your suggestions were spot on and exactly what I was looking for.


Thanks again for all your help!



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