Milltronics post going G2 (CW) when it should go G3 (CCW) on a few arcs

[mlinesFEDXV]

I have an old Milltronics partner one and I am using the generic Milltronics post processor.  Even though the simulation looks fine:

I get 'mouse bites' in my part.  I ran the program slowly and found the line numbers of the offending arcs.  There were only four arcs that were bad, they processed as G2 but should have been G3.  I edited them to be G3 arcs, now they show up in the editor but the machined part is fine!  (I used HSMworks editor for the editing even though I am using Fusion 360 to generate the Gcode).

Almost all of the arcs were ok, it was just a few that went the wrong direction.  Unfortunately the next step is some complex contouring so I can't really run the program slowly and hand-edit the gcode, that would take weeks.

[HughesTooling]

Can you upload the f3d file and your post if it not a generic one. One setting to experiment with on the post dialog, there should be a setting for minimum arc length try increasing it to 0.025mm. I've seen some controls do a full circle if it's given a short arc, so instead of moving 0.01mm it does a complete circle.

Mark

[mlinesFEDXV]

I don't know how to upload the file, it only gives me the option under <save as> to "save to a project in the cloud"

I don't know where to find the "post dialog", If I go to "actions", "Post Process" there are a lot of values such as "(built-in) minimumCircularRadius" which is currently set to 0.01 mm, is that the setting I change to 0.025 mm?

[HughesTooling]

You'll find export on the file menu just save as an f3d. And yes try setting the minimum circular rad to a bigger number and the cord length as well.

Mark

[mlinesFEDXV]

Increasing minimum arc length and chord length didn't have any effect.

[mlinesFEDXV]

Increasing minimum circular radius and minimum chord length both to 0.1 mm DID work!  Yea!

[HughesTooling]

Although it looks like you've figured out the arc problem I took a look at your design and I'm glad I did. You are misusing model selection in your ops, for most ops the model selection from the setup is all that's needed and you don't need any selection in the op.

This is very bad practice because the op will not see the rest of the model and sooner or later you'll get a toolpath through the job!

You should use touch surfaces, done like this the op sees the rest of the model.

Where model selection comes in handy is it allows you to add surfaces to the setup model for just that op. So you can add a cover surface over the engraving so you get a smooth toolpath.

Like this, surface added to the setup model only seen by this op.

Mark

[HughesTooling]

Here's a screencast to demonstrate how to make a patch to cover the engraving and how to use it with model selection to make a smooth toolpath. When you need to ad ops for engraving just hide the surface, the ops where it's already selected with still use it with it hidden. I've attached an updated file, to import use New Design from file on the file menu.

Mark

[mlinesFEDXV · Accepted solution]

Add PB=81 to the post to turn off trig help.  You don't need trig help since you aren't programming by hand like back in the '70s and in this case it does the opposite of helping once the arc radius is smaller than the floating-point precision of the machine.

e.g. somewhere inside function onOpen() add "writeln("PB=81");"

I added it towards the end:

. . .

switch (unit) {
case IN:
writeBlock(gUnitModal.format(20));
break;
case MM:
writeBlock(gUnitModal.format(21));
break;
}
writeln("PB81=2");
}

function onComment(message) { . . .

You can (if needed) use PB81=0 to turn trig help back on.

[Anonymous]

@mlinesFEDXV

This worked perfect!

Thank you! I was spending a lot of time verifying code, 50000-100000 blocks.

chris