Quick vent - Bring some vision to raster tool paths Vetric!

I'm tired of breaking cutters, so this is more a suggestion to Vetric than a question.

When you do a finish cut on an object and you have a large shelf drop off that runs parallel with your cut, you will break your cutter as it will follow the low path while there is still overhang on the upper face. There are a couple of work arounds such as change the raster angle, import into Vcarve and do a 2d "go around" of the ledge, or hack the gcode so the cutter clears the upper edge.... Each have there own problems associated with doing so.

In wood you can get away with poor tool paths, but unfortunately steel has no forgiveness, I'm sure it's not just 3dcut but all Vetric 3d rasters that are blind; and given my cut 3d was compiled in 2007 some improved intelligence in the toolpaths wouldn't go astray!

Farmer...
A 3D finish toolpath assumes that you have removed material, if needed, by a proper roughing toolpath. I prefer the Z level, with .100 (2.5mm) steps, .200 (5mm) stepover and a .040 (1mm) machining allowance using a 1/4" (6mm) end mill. I find it hard to imagine a properly setup finish toolpath would break bits if it followed a roughing, but if so, post a pic and the guys here can give you a strategy for success

Quote:

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Originally Posted by islaww

Farmer...
A 3D finish toolpath assumes that you have removed material, if needed, by a proper roughing tool path.

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This is actually the issue and why I said a work around is to remove material.

OK, so to explain what I'm talking about. Pic1 - This shows the finished tool path for a simple ledge running parallel. You can see the cutter follows the upper ledge and then drops to the lower ledge. It's a 4mm cutter at 10% so it needs 5 passes = 2mm to clear the ledge. This is shown in Pic2. You can count 4 passes in thin air and pass 5 on the bottom.. it does what it should.

The problem (as you point out) is in the roughing cut. Pic 3 shows that because of unintelligence (regardless of stepover) it leaves a huge amount of material where it shouldn't be (where the mouse cursor is).

To overcome these sort of issues particularly with technical objects of different angles (and those that exceed the finishing tool flute length) after roughing I usually have to double check and check again and measure 10 times, and then import the object into Vcarve Pro and remove the excess material - Pic4. You can also see in pic 4 it has also left a huge amount of material that shouldn't be there where the mouse cursor is.

Faces that are higher then the flute length also have this issue. But anyway I just needed to vent about this and now I feel better... The Vetric software has several limitations and no decent post processor functionality (such as coolant support, spindle direction, return to home, blah blah), but it is extreme value for money and I keep using it because it simply does a lot of what my much much more expensive CAM just won't...

BTW. Thanks for the suggestion on the Z level. Pic 5 shows how for this object it would leave even more material, particularly where the cursor is. A smaller end mill may get to the lower level and/or I could overlay roughing tool paths (which is what I do with by adding 2d tool paths really)... but as I said in my initial post, workarounds have there own associated issues.

Cheers

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FYI Upgrading to Vcarve 8 where you can set boundaries/vectors on roughing and finishing paths makes this issue redundant. Thanks Vectric.