3D HS Toolpath: Avoiding Floors?

[ccs86]

Hi guys,

 

I am trying to get more control out of my finishing high speed toolpath in Mastercam. My strategy is something like this so far:

 

-Opticore with a 5/8" flat end mill, leaving 0.035 on the walls and 0.0 on the floors.

 

-Drill a few holes with FBD

 

-Hybrid finishing path with a 0.25" ballnose.

 

My problem is, that the Hybrid finishing path wants to touch everything by nature, including a few large flat floors that already have a nice finish. I'd like to save a whole lot of air cutting and avoid these floors.

 

Check geometry is a no-go with the HS finishing paths. Containment only seems to limit cutting to within the chain (not to avoid the chain). And simply not selecting the flat faces causes Mastercam to do some funky stuff.

 

Any insight would be great!

 

Thanks!

[ccs86]

I figured out a dirty hack this afternoon:

 

Using the shallow step-over feature, I set the limiting angle to essentially 0, and the stepover amount to 1". This effectively ignored anything totally flat, and used my stepdown everywhere else.

 

Unfortunately, this method doesn't seemlessly blend the finish path into the floors, and I'd like to use the shallow step-over feature for its intended purpose (improving finish on shallow angles).

 

Help!

[MotorCityMinion]

Don't try to limit the tool path. Use the trim function, setting up trim curves just past your desired blend area. I use this technique to force a scallop path to do what I want. Of course it works well with other tool paths.

 

Be aware that you can influence the tool path by creating boundaries. On the flat floors, create a smooth boundary close to the center, perhaps circular , elliptical, or rectangular, with large corner rads, anything but sharp corners. Try to do the same with the outer boundary, even if this means creating dummy drive surfaces. Next, run the tool path in back plot before you trim it. Save the back plot as geometry to a new level. Pick the geometry you want to keep to use as trim curves. Change those entities to a new color then use quick mask colors to delete the rest.

[ccs86]

I'll admit that I don't totally follow what you described for using backplot to save geometry. Basically, I just created sketches in the tool plane that describe the floors I want to avoid, picked those sketches as trim selections, then chose a random vertex that was in the desired cutting area.

 

This seems to work great for excluding regions in a top down, tool plane view...

 

Is there any way to trim this same path from another plane's view?

 

Here is a picture showing this finishing path. You can see the avoidance of floors (thank you again!), but I would love to avoid the area I bounded in red. A 5/8" flat end mill will have already cut this outer profile and I don't want the little 1/4" ball nose wasting time chattering around the outer walls.

 

Much appreciated!

[mkd]

if you just want to finish the corner radius (or top edges), consider using Finish Scallop. only pick the radii as drive surfaces.

[ccs86]

if you just want to finish the corner radius (or top edges), consider using Finish Scallop. only pick the radii as drive surfaces.

 

 

That doesn't seem to work because that radiused edge curls all the way under the part (look on the far right side of the picture). This seems to force those full depth toolpaths around the perimeter.

[MotorCityMinion]

Using back plot to same geometry is very cool. When you run back plot, theres an icon in the second row from the top, far right, that looks like a floppy disk. Run the back plot and when it finishes, select that icon. A message will appear asking you what level you would like to save it to. Pick a level number, hit the green check mark and done. I usually save it with out the rapid moves turned on. Now you can analyze the geometry, copy it or do what ever you like. In your case, I would select the geometry that comes closest to where you would like to trim your tool path, change the color of that geometry, and delete the rest. Tons of possibilities here.

 

The boundary chains I spoke about will influence the general shape of the tool path and offers up more variations for trimming.

 

"Is there any way to trim this same path from another plane's view? "

 

Yes, set the T/C plane to front or right or whatever plane suits your needs. Create your trim boundary and be sure to be in that plane when you use the trim function.

 

Some people will think this is too much work but it really only takes a few minutes and offers a level of control that otherwise would not be possible.

[ccs86]

Thanks for the help MotorCity!

 

I'll have to explore back plot more. I usually just use verify. What benefits would you say back plot has over verify?

 

I've also been trying to get machine simulation going, but getting things correctly oriented seems clunky.

 

Let's say I've already trimmed that toolpath from the Z-up tool plane, to avoid the flats. I'm stuck there right? If I choose trim toolpath again, that same finishing path is not selectable from the list anymore. I tried adding the side view sketched chain to the original trim operation, but it gets ignored.

[MotorCityMinion]

" What benefits would you say back plot has over verify?"

 

In general, it offers up a different perspective for observing your work. For one, you can see the cutter path relative to you geometry, literally look at it moving along the chain, or staying off it. See the leads ins. See the coordinates. Analyze saved back plot geometry. Drive saved geometry as a tool path. See the rapid moves. See whether or not you selected the correct hole for a certain drill size.

 

Verify shows none of this, you see a tool either cutting a chunk or moving through air and thats it. I look for gouges, verify against a finished solid or a stl. I'll section my verify for clarity, and I'll measure results with the cut. I use both tools about the same amount one will catch something that the other misses. FYI. 2/3 of the guys in my shop don't use verify and can't set it up properly, especially with round stock. They were shown the basics of back plot and it works fine for most of the 2d work.

 

I'm stuck there right? Not necessarily. Use depth limits to stay off the floor, and trim from the right or left. When you use depth limits though, the tool path shape can change vs trimming from the top view.

[ccs86]

Thanks again for the help Motorcity! Much appreciated...

 

I have been able to reduce my cutting time from nearly 3 hours, to just over 1!