Roughing and Finishing

[jludwigC73AM]

I've read posts here and articles elsewhere and watched Youtube videos, and I'm still having trouble wrapping my head around how to make roughing and finishing passes in Fusion 360.

I'm working with foam. The end mill has a tendency to create long strips that wrap around, so I'm trying to avoid a simple pocket or adaptive clearing tool path. As seen in this video, I'm trying to create the contour around the edge and then parallel paths where the strips break off and evacuate. 

https://youtu.be/YAgT8oNwKhQ?t=294

I've also experienced that when cutting contours in foam, I get ugly fuzzy edges no matter what. It seems like it's because there's not enough room for the chips to get out, because when pocketing up against an edge, it looks perfect. That makes me think I could use a rouging and finishing pass. I did something similar in Carbide Create, but that involved setting an offset edge wider than the diameter of my end mill and then choosing pocket. It seemed to accomplish what I believe roughing and finishing refer to.

I would really appreciate some screenshots to go along with the terms used by Fusion and then like a Simple English Wikipedia version of what each step or term means/is doing.

I have attached the file I'm working on. You can see two bodies. Right now I'm referring to the body that only has one off-center cylindrical pocket. I would like to do a single pass, say .75" deep max per pass, to rough out the edge of the circle with maybe a tolerance of .125" or less. Then have the end mill come around again and do a nice pretty pass right up against the edge of the shape. I don't know if it's better to do the rough pass all the way to the bottom of the hole and then finish all the way to the bottom, or if I should rough then finish at each stepdown. I don't know what all will transfer with the archive file, so you can assume the end mill I'm using for the whole job will be a .25" diameter, upcut, 2 flute, flat end mill, 24000 RPM, 144 IPM.

[hyperbolicindustries]

Are you using a 1 flute down cut bit?

[jludwigC73AM]

The end mill I'm using for the whole job will be a .25" diameter, upcut, 2 flute, flat end mill, 24000 RPM, 144 IPM. It's an Amana 46272-K, a foam cutting end mill. I have great results with it already. I'm just trying to understand different terminologies and how to affect them, given that Carbide Create is largely  a dumbed down system.

[hyperbolicindustries]

Look into a Downcut 1 flute if you are working in foam. It *should* help with both tearing because the cut is directed downward and evacuation because you would take a larger feed per tooth to create a larger "chip" that has more heft and is more easily thrown out. 

I say should because I have never worked in foam but I know know that is supposed to be the suggested method.

[jludwigC73AM]

Yes, I know that I could continue in my ignorance and throw more money at the problem until it does what I want, but I would prefer to learn more about the software I'm trying to use right now.

[seth.madore]

---

@jludwigC73AM wrote:

I would really appreciate some screenshots to go along with the terms used by Fusion and then like a Simple English Wikipedia version of what each step or term means/is doing.

---

Have you given THIS a read?

[jludwigC73AM]

Yes, a couple times, but I guess I can always read it again.