Problem- Pocket mill leaves islands V21

[SteveS]

I am pocket milling letters from the BCC font library and I am getting small islands or slivers when done. Zooming in on the tool path it is complete, but the code doesn't seem to "jump" to all the islands.

I have gone in, selected the island path after the first one being cut identifies what is missing and had the CAM generate code. Then the milling is complete for the next one.

Being all of this to date is wood, I can go in with a sharp chisel and shave the pocket flat. When doing only one, this is the inspection and manual fix way.

I am only using the "rough" and not "finish" in the pocket generation. Again, the path is there on the CAD side, just not connected in the initial code.

Steve.

[moldmker]

If you are saying that there are pockets that are missed in the code:
Is there a dashed line connected to the paths that are not cut?

If not, you could manually add one to connect all the paths so the Cut Auto works on all.

If you are saying that slivers are left standing within a pocket routine:
Reducing the stepover to 50% or less usually helps.

moldmker

[Ed from NY]

Can you post a picture?

How high/wide are these islands? Are they very small in height and size? Could it be the tool radius at the bottom?

A picture would really help

[mxer]

Reduce stepover until islands are gone.

[SteveS]

Here are some files that show my situation.
Testing Pocket MIll.Zip file is Bobcad .cad with CAM. System won't allow direct upload of .cad file.
G-code that was created is also in the zip.

Pocket Mill 1.bmp and Pocket Mill 2.bmp are screen shots showing the missed islands. The red is from "geometry from cnc." The remaining "black" lines are the pocket mill path that didn't get picked up from the auto generate CNC.

To be clear, the pocket function generates enough path to clean out the pocket, but the code isn't generated.

This font is Braddon, but it happens for me on others also.

Stepover is set at 50%, but it occurs with less or more.

When selecting the pocket path I get the "start here" tail to point out, right click and select chain. Then, edit, selection and reverse selection. Then over to the CAM side and auto generate icon.

Steve.

[Crop circle is another pain in my life, but I am getting to be expert at editting the code afterward. I have a V23 seat, just haven't had time for the learning curve to change over.]

[moldmker]

I think I see what's going on.

Your Chain Gap Tolerance is set too large and it's allowing your toolpath to jump around rather than follow the chain.

Go to File > Environment > General tab and set the Chain Gap to a lower number (I'm in inches and .0001" works).
Save the drawing and reopen. You should be able to chain select the whole path now.

The alternative method is to have your Auto Preselect selected under Environment > Defaults.
With this selected, your toolpath is preselected when you generate it (regardless of chain gap setting).
Then all you need to do is click Cut Auto. (obviously, the CAM window needs to be open while generating the pocket path)

Your crop circles look pretty severe. Messing with system tolerances can help there too.
Also helps if your control accepts R codes in place of Is and Js.

moldmker

[SteveS]

Moldmkr,

Your recommended 0.0001 inch in my metric world is 0.002540 mm.

So I checked my environment setting chain distance and it is 0.001 mm, which is actually smaller.

General accuracy is 0.0002 mm and pick distance is 10.

I went to the CAM side and got some screen shots of the setup to attach.

Steve.

[moldmker]

Just for giggles, take your gap tolerance to .0001mm, save and reopen drawing and see if you can chain select the whole path.

I have my general accuracy set at .0001".
I tried setting it tighter once to resolve other issues and recall that the crop circles got worse.

moldmker

[SteveS]

Moldmkr,

Changing chain gap to 0.0001 fixed the missed islands and the crop circle went away in this sample.

Is there any logic behind this that you could try to explain?

Also, what does "Pick Distance" in environment refer to?

Steve.