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Kendo

Weird arc slot

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Could use some ideas on how to get this slot cut.

Mastercam breaks these arc segments into straight lines and it'll ruin the part

This (finish pass) should be 5 "G2" lines, two will have Z added for helical 

Then I need to think about how to rough down to the bottom.

I understand cutting to this wireframe will (theoretically) violate the surface at the point of tangency in the ramp segments.

Just so happens the floor is missing in the cast material so I think I can get away with it.

image.png.06c2cc934eddcf207a3a1e630b3b0779.png

 

T2 DEEP SLOT.mcam

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Lay it on the side and cut it from the top.  Looks like you have a bunch of other features that should be done on a 4th axis...

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I should have mentioned, this slot has been sliced open so you can see it.

I cut the rest of the part away with a big circular extrude/cut that sliced down the center of the arc slot

It's a closed slot that has to be cut in the vertical orientation as shown with zig-zag helical motion

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I'd a surface rough pocket, Im not sure how wide it is, but it looks like you can use a 1/8 endmill

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Only a couple of the arcs are on the xy, yz, xz planes. You won't be able to filter/create arcs on circles that are not on the G17, 18, 19 planes

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Thanks Guys,

AMCNitro, I'm stuck with an on-size tool right down the center since this is for mass pro

cam-eleon, I see what you're saying, one of the ramp sections is actually a nurbs spline and mastercam won't even simplify it to an arc (don't know why). I closed the other one below and it's easy to see it's not on G17, I just hoped mastercam could take it as a helix in G17 since from the top view its just an arc with rise/fall in Z...

So... If you construct helical geometry (on G17), and chain it as a countour, mastercam calls it "3D" and can't spit out simple G2 X-Y-Z-I-J ??? I tried- can't get helix wireframe that's not a nurbs spline... maybe I have to piece it together from rotated arcs?

I'll probably end up letting mastercam give me G2 code for the flat arc that's projected to the top plane and then manually add the Z values to get a helix

Is this what the pros would do!?

image.png.a11f7c439ac9ce85308090ba9b4257ed.pngimage.png.9b905bb36e34acbdcb55222d1fad759b.png

 

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From what I know  machines will only execute proper helical code on arcs in the G17 plane. Helical code is a G02/3 with a linear Z motion. Circles on the G18, G19 plane by definition will contain a Z.  There are 5 arcs in the chain. If you close each arc and don't see a perfect circle as viewed from the top,front, or right/left then there are no G17,18,19 arcs.

image.png.2f80f378661c64e7d300463b183968bc.png

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I've tried project before on similar cuts (the tiny slots that are at the ends of these 3/16 arc slots)

The results were not very smooth.

This one's even tougher because there's no floor at the bottom of the slot to project to

 

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I'm old school. Sketch in every rough pass with a ramp type 2 d contour if you have to. Then all arcs are/should be in the top view. Worry about the last pass/passes as a 3d cut.

Then the boss is off your back.....

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18 minutes ago, AMCNitro said:

Can you post the whole model?  

Look in the solids manager and suppress the extrude cutting off the rest of the part.

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10 minutes ago, crazy^millman said:

Look in the solids manager and suppress the extrude cutting off the rest of the part.

Didn't think of that...

It wont let me post more than 1.33mb, so I dont know how to post the file.  What I did was a Surface rough pocket  and surface countour.  It looks great.  I didnt use your 3/16 tool. I used a 5/32

1176970909_wierdslot2.thumb.png.5f18dccf6d731d98bff17107f097830b.png

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you could try and run the arc3d chook on your initial toolpath

it does create some helixes but not all

 

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Thanks ajmer I did get some results out of the arc3d

 

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The customer sent me a spline to use for this path since they design in-house so I got lucky

BUT... driving the tip of a ball endmill with this spline still violates the surface because the mill contour ignores the tangency

 

image.thumb.png.b4670fa980c811705d4daaa4157d8e4a.png

T2_DEEP_SLOT_new.mcam

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3 hours ago, Kendo said:

LOOK what I did Yall! 😎

image.thumb.png.ecc622d559ca1f505dd970abc07af50c.png

Project toolpath?

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