3D roughing boundary issue

[jamin35008]

I’ve been attempting to import a 3d map stl file of Canandaigua Lake in western NY for a couple of days and everything is looking relatively good except my roughing pass is going outside my selected vector I’m using as a boundary. This is creating the results shown in the picture. I would like everything to remain within the circle shape of the finished area and not create this extra "shelf". Don't mind the line going North and South, I was trying to see if it would be possible to add a road map.

Is it doing this because it needs the additional room for the bit? I notice its only doing this around areas that have the higher terrain so my though was the it has to come outside the boundary to keep from carving into the hillside???

Contrary to that thought I would believe that the software would see that the bit shouldn’t travel outside the selected vector and not carve in areas that its not going to fit.

I’m using a ¼ in endmill for roughing and a 1mm tapered ball nose for finishing.

Thanks for any thoughts of what’s going on here.

[jimwill2]

When you create the roughing toolpath you should be able to set the boundary offset to -.25 (the diameter of the bit.) That should keep the bit within the vector. I'm using Aspire but I believe Vcarve should have the same option.

[gregk]

In case of roughing toolpath the tool center have to be kept within the selected boundary. This is to help when you use the same boundary with finishing toolpath.
Since roughing tool will be allowed to travel half of its diameter outside of the selected vector, it is more likely that it will remove enough material for subsequent finishing toolpath, to prevent tool breakages.

If that is not a concern for you, you can offset the boundary inwards by half of tool's diameter, then use that vector as boundary for roughing toolpath.

I hope this makes sense.

Greg K

[jamin35008]

In case of roughing toolpath the tool center have to be kept within the selected boundary. This is to help when you use the same boundary with finishing toolpath.
Since roughing tool will be allowed to travel half of its diameter outside of the selected vector, it is more likely that it will remove enough material for subsequent finishing toolpath, to prevent tool breakages.

If that is not a concern for you, you can offset the boundary inwards by half of tool's diameter, then use that vector as boundary for roughing toolpath.

I hope this makes sense.

Greg K

Greg,

Greg,

This is what I originally thought but didn't know exactly how to prove it. I figured it must be making room for either endmill during roughing or the ball nose during the finishing pass. Thank you for clearing that up. I will keep the what Jim said about the offset in mind if I know I’m not going to break anything.

This design was going to go in the middle of a wall clock. So I want the edges around the map to look finished as well. I was thinking of somehow incorporating a molding toolpath around the map? Maybe I need to purchase a long ball nose that will be able to reach all the detail without the worry of bottoming out and use the offset to eliminate the roughing from going outside the boundary of the finishing pass?

Something like this: JERRAY CNC Carving 3.92 Deg 2 Flutes Tapered Angle Ball Tip Radius=1.0mm X 1/4" Shank Tungsten Solid Carbide HRC55 with TiAIN Coated 3" total length.