Fanuc Comp Issues, I want to compile some info here to help me and others in the future.

[huskermcdoogle]

So I have a multitude of issues with cutter comp. I don't want to start a conversation on whether you should run wear, or full diameter comp, because hypothetically for this conversation, it shouldn't matter.  I see applications for both and feel any engineer, programmer, or business owner, operator, or hack should be able to decide on their own.

On to problem #1

Oh wear to start....

Alright, so lets say I have a simple id circle mill path, I have wear comp on, 0 in the register, and a short linear move leading into the arc leadin.  In G18 with G41 it works just fine, and I can adjust it.  If I switch to G42 (head is flipped other direction pointed up the y axis) it gives me a "No Avoidance G41/G42" alarm, even with zero in the register, didn't try a value, but sometimes just putting a micron in there will make it go away, but .025 microns will bring back the alarm, and sometimes in seemingly simple areas. 

This is in G18 spindle pointed minus, and will work.

G1 X35. Z20. F600.
G41 D5
X34.84 Z20.014
G3 X34.081 Z20.919 I.16 K.905
X35. Z21.837 I.919
K-1.837
K-1.837
X35.918 Z20.919 K-.918
X35.16 Z20.014 I-.918
G1 X35. Z20.
G40

This is in G18 spindle pointed plus, and will not work.

G1 X35. Z20. F600.
G42 D5 
X35.231 Z20.02
G2 X36.331 Z21.331 I-.231 K1.311
X35. Z22.663 I-1.331
K-2.663
K-2.663
X33.668 Z21.331 K-1.332
X34.769 Z20.02 I1.332
G1 X35. Z20.
G40

It seems to me this is a parameter issue.  Does anyone have a decent understanding of how to get the parameters setup in the control such that comp behaves in a nice manor?  This applies to both G41 and G41.2, I get the same issues with both.  It's god awful annoying, and time consuming when you are fighting stupid comp issues, that shouldn't exist in the first place.

What I would like to do is compile some parameter settings to look at and compare, and maybe find someone who has a setup that works well, what thier parameter settings are, and what rules they use when applying comp on a path.  Not having comp on a G2/3 is obvious!  I am talking things like, how long a linear move on startup or do you startup on its own line with no movement, do you force planar positions output on all moves.  I want to break this down and come up with possibly come up with a resource for people to look at.

As of now all I care about is Fanuc 31i controls, but most of these things will apply to any Fanuc control from the last two decades and into the future most likely.  At some point I will likely give a shout to Fanuc America and see if I can get some support, but for now, let's start here.

Thanks,

A frustrated fellow programmer.