Struggling with Fusion360 CAM for a ball-nose slot

I've been pulling my hair out trying to model the CAM in Fusion360 for what seems to be a simple part. It's small cylindrical puck with some machining on both sides. I'm "self-taught" with Fusion360 and feel reasonably comfortable on the CAD, but maybe I messed up something in the model?

But the real problem (aside from the fact that I am also very green at machining and CAM) is the CAM for a curved slot in my part.

The puck has a center bore, four holes in around the bore, and some passages. Most of the passages are flat-bottomed and I finally cheated my way towards successfully machining the cylindrical one (it's a 3/16" wide channel, but it wouldn't allow a 3/16" flat end mill tool, so I cheated on the dimension by saying it was 0.1874 instead of 1875... then that worked). I've already tested it on the mill and it was spot on.

FYI, the material is Delrin 100AF

Okay, so the problem is that darn rounded slot. I have tried what seems like 100 permutations and combinations of strategies and I just can't get there. Fusion360, with me at the keyboard, refuses to mill the part of the rounded slot closest to the center. I've tried multiple ball-nose endmills, I've tried drilling it. But all the strategies want to "lift" the tool as it gets closer to the center and create a shelf. And... even though I have REST machining, it also always wants to go into the center bore, even though I believe I've completely machined the bore already.

I've pasted an image of the part below, and I'll work on uploading the fusion file too.





Any and all guidance and help is appreciated!

Crud - the CAD file won't upload because I get the following message:

Wire Spool C76-EPA-3213A-2 v18.f3d.zip: Your file of 294.5 KB bytes exceeds the forum's limit of 97.7 KB for this filetype

Any suggestions how to get it to an uploadable size?

Thanks,

Matt

I don’t have a solution for you, but I found the Autodesk Manufacture forum to be very helpful and quick, you will usually get a couple answers within an hour, and it’s easy to upload a fusion file.


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Thanks Ripperj. I've posted over there as well and will keep my fingers crossed for some guidance either here or there!

There is something going on with your model, see circled red part. It looks to me like a thin lip that didn't get removed during the modeling process (I could be wrong though and maybe it's supposed to be there). It seems like it's messing up the selection process for me. I usually use Inventor so I'm not great at fusion, but I played with it for a few minutes. Go back and edit you path, uncheck rest machining, check model and select the surfaces you want to cut ( they will highlight blue), uncheck include setup model. See if that works for you.







Here is what I came up with

Lastrada - I see that little remnant. I don't know what it is, or why it is there, and I hadn't seen it before. I appreciate you seeing it and pointing it out. I'll get into the model later this evening or tomorrow and get rid of the remnant and see if that fixes it. I'll also try your adaptive strategy and make sure I can highlight that for machining.

I will report back! Thanks!

Lastrada -

I think I cleaned up the design file and those artifacts are now gone. That helped a LOT. I'm still getting a few funky things on the CAM side. I followed your advice on the Adaptive setting, but it didn't work perfectly. When I selected "Tool Center on Boundary" it machined outside of the the ball-end area of the hole (but not the slot) and made a mess. So I changed that to "Tool Center Inside Boundary". That seems to work, except two things:

1. It doesn't machine the outer diameter of the slot, and
2. There is a funky artifact one the inner side, left of the ball-end hole. Maybe its nothing, but it sure looks strange. You can see it in the attached image (brownish area left of the machined area).

Screenshots below.

And another question. Since I didn't seem to be able to upload the Fusion360 file from this website, did you grab it from the Autodesk forum, or do you have some magical powers to grab files from my computer?

Thanks a ton, and I'm all ears if you have further suggestions for the outer diameter (and I can upload the fixed design fusion360 file if that helps).

Sincerely,

Matt

Hello.
Is the front wall of the slot tangent to the bottom rounded part. Also in the future just draw a circle in the middle of your flat slots and run a mill down the center of it without left or right cutter comp

Yes, the front wall is tangent.
Thank you for the suggestion of drawing the path. I’ve not done that yet because I had just assumed F360 would have lots of other ways to machine the area. But drawing a line is certainly simple.

I appreciate the help.

M

plutoniumsalmon said:

Hello.
Is the front wall of the slot tangent to the bottom rounded part. Also in the future just draw a circle in the middle of your flat slots and run a mill down the center of it without left or right cutter comp

Click to expand...

Without being able to load your model and see what's going on, it's difficult to say what actually is causing your issues.

That said, I often drive a tool path off a sketch instead of the model, (using the Trace strategy in CAM). It's a really simple way to define exactly where you want to center/tip of the tool to go. It's a relatively "dumb" strategy, so typically will not do anything unexpected.

PM