Help for a student: Creating a pocket with an area NOT cut out.

[EdTeacher]

Hello, I am a CTS (Career and Technology Studies) Teacher in Alberta, Canada.

I have CNC as part of my Design Studies Class. MOST of what my students want to do, I can figure out, but between a lack of funds for training (It's K-12 Education) and my student pushing the limits of what we can do (which is great, but I am not sure how to do what he wants to do lol). I need a bit of help.

I am not Just teaching Mastercam in my class. I have 2-3 students a semester who do Mastercam/CNC projects. So it isn't my strength. But I like to encourage my students to try different things.

Running MasterCam X9.

In the sample picture I have provided (The file he is working with is a bit more complex, but the same idea) I have a circle that we want to cut out in a solid material, with leaving the inside shape (rectangle here) still raised to the original material height. So a pocket idea, but not cutting all of the material out leaving a sticking up portion. It isn't turning out right when we do this. We are having troubles getting it to NOT cut the rectangle portion.

I don't know how we have to create this in 3D, or tell it to not go into a certain area, etc. etc.

I also included the BASIC file that we are using as a test for how to do this.

Any information/guidance you can provide I appreciate.

Thank - you.

Philip

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[Superman]

Try this

2D pocket ..... select the circle AND rectangle as your geometry ( 2nd profile is considered as an island ) ( & they have to be planar but not at the same height )
- don't use zigzag style......, high feed puts rads on corners & makes going thru gaps dodgy.......... use constant stepover ( with or without the clean corners )
- ideal tool size should fit thru all gaps ....the gaps are after you have applied any wall offset & finish passes in that operation
( ie 8mm tool, with 0.2mm rough allowance & 2off 0.1mm finish pass allowances === 8 + (0.2+0.2) + 2x (0.1+0.1) = 8.8mm is smallest gap the tool would pass thru
( - not greatly important in Alum.... the tool really only needs to cross each other to "break" the gap, as the cusp would go in the finishing passes )
- set plunge ( off/ramp/helix) accordingly
- stepover no greater than 65% of the base diameter size (if a bullnose or taper cutter)... drop this to 50% if problems in acute corners

[EdTeacher]

Thank you very much, this worked well and achieved what we want. I had one or two minor changes from what I was doing, but they made a big difference. Thank-you.

Ed Teacher