HeeksCNC has some very good operations for drilling and profiling that would be handy for this, but there is nothing in the way of automatic roughing or multi pass sawing. I ended up using some other CAD tricks and HeeksCNC's python scripting to make things work.
Here is the drawing as it imported into HeeksCAD:
The stair step shaped part is the thing that I am ultimately cutting out. On the right and left corners of it, I have added (in another CAD program) some roughing passes to cut the corners of my stock off:
The roughing actually looks like this on my Bridgeport mill:
I also needed to saw some slits in the sides of the part. I wanted to do the sawing with 4 passes of the saw blade on each side. I used my CAD program to offset the final saw path back half the diameter of the saw blade and then offset it 3 additional times by .050".
Obviously, it's critical not to retract the saw blade in the Z axes at the wrong time,and I wanted to keep the saw blade down at the right Z level while doing these passes, so I needed to do something to avoid using HeeksCNC's usual profiling method of doing a path, retracting in Z and then doing the next path. I resorted to some Python scripting tricks.
1. I selected the lines that I had drawn in CAD for sawing in HeeksCNC and generated a Profile operation with them. This allowed me to extract the geometric points that I needed.
2. I copied the python script from HeeksCNC and pasted it into my favorite text editor.
3. The script was easy to understand and manipulate- I just wanted a series of 'feed' and 'rapid' in the right spots.I didn't use any loops, because I was lazy....
Here is my sawing script:
comment('tool change to 2.755 saw')
tool_change( id=4)
spindle(300)
feedrate_hv(15, 6)
flush_nc()
clearance = float(0.5)
rapid_down_to_height = float(0.07874015748)
start_depth = float(0)
step_down = float(0.156)
final_depth = float(-0.156)
tool_diameter = float(2.755)
rapid(z=0.1968503937)
rapid(x=6.218827292, y=-1.060352717)
rapid(z=0.07874015748)
feed(z=-0.156)
comment('pass1')
feed(x=6.076573626, y=-1.200936811, z=-0.156)
feed(x=4.101644628, y=0.7974459866, z=-0.156)
comment('Rapid Away')
rapid(x=4.266169148, y=0.9154947677)
rapid(x=6.218827292, y=-1.060352717)
comment('pass2')
feed(x=5.994311367, y=-1.25996122, z=-0.156)
feed(x=4.019382367, y=0.7384215961, z=-0.156)
comment('Rapid Away')
rapid(x=4.266169148, y=0.9154947677)
rapid(x=6.218827292, y=-1.060352717)
comment('pass3')
feed(x=5.912049106, y=-1.31898563, z=-0.156)
feed(x=3.937120107, y=0.6793972059, z=-0.156)
comment('Rapid Away')
rapid(x=4.266169148, y=0.9154947677)
rapid(x=6.218827292, y=-1.060352717)
comment('pass4')
feed(x=5.829786846, y=-1.37801, z=-0.156)
feed(x=3.854857847, y=0.6203728154, z=-0.156)
comment('Rapid Away')
rapid(x=4.266169148, y=0.9154947677)
rapid(z=0.1968503937)
comment('rapid_left')
rapid(z=0.5)
rapid(x=-2.953405945, y=0.07385377598)
rapid(z=0.07874015748)
feed(z=-0.156)
comment('pass1_left')
feed(x=-2.787292165, y=0.1930428677, z=-0.156)
feed(x=-1.668332953, y=-2.357971772, z=-0.156)
comment('rapid away')
rapid(x=-1.834446732, y=-2.477160866)
rapid(x=-2.953405945, y=0.07385377598)
comment('pass2_left')
feed(x=-2.704235276, y=0.2526374134, z=-0.156)
feed(x=-1.585276063, y=-2.298377244, z=-0.156)
comment('rapid away')
rapid(x=-1.834446732, y=-2.477160866)
rapid(x=-2.953405945, y=0.07385377598)
comment('pass3_left')
feed(x=-2.621178386, y=0.3122319591, z=-0.156)
feed(x=-1.502219173, y=-2.238782677, z=-0.156)
comment('rapid away')
rapid(x=-1.834446732, y=-2.477160866)
rapid(x=-2.953405945, y=0.07385377598)
comment('pass4_left')
feed(x=-2.538121535, y=0.3718265047, z=-0.156)
feed(x=-1.419162283, y=-2.17918815, z=-0.156)
comment('rapid away')
rapid(x=-1.834446732, y=-2.477160866)
rapid(x=-2.953405945, y=0.07385377598)
rapid(z=.5)
program_end()
Here is what things looked like on the milling machine:
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