Setting up the 5axis CAM system setup on the Haas VF2 today!
5-Axis work is still pretty new to me, and I've only had experience in it on my Pocket NC, which, as I'm learning very quickly, is quite different. I set up the softjaw fixture my boss made a few years back to hold my stock in place on the B-axis bed of the trunnion and dialed the rotation off the back edge of the dovetail vice.
Before running the entire program, I wanted to test it out to ensure everything was lined up correctly and avoid crashes. I'm very glad I did this as when I went running a basic facing operation, the spindle went to the back corner, and if I weren't there to stop it, it would have crashed into the 5-axis trunnion. The interesting thing was that it was perfectly inverted; everything was in the correct locations just on the opposite side of where I wanted it to be. I looked around online a bit to see if it was a common problem and couldn't find any information on everything being in the wrong place, there were instances of the a-axis turning the wrong direction, but those were only one of the axis.
I decided to re-download the post-processor Fusion360 had for Haas machines and repost the code without making any changes. It turns out that was the primary solution; however, now the a-axis was on the wrong side (wasn't before), and it would cut the material with the base of the trunnion toward me, which would work, but I would have no supervision of what goes on. I remembered reading all those posts of people having similar issues, so I went back and followed the outlines they suggested. I opened up the post-processor code and found the section outlined; I then changed the parameters for the a-axis rotation to go in a positive direction instead of negative (rotating it +90deg instead of -90). Unfortunately, this didn't work, and spent a few hours trying to problem solve it. The quick and dirty way to fix the issue was to remove the minus sign in the posted G-code, but long term, I know that would cause significant problems if I forgot to do that.
I finally figured out what the problem was; in the post-processor program where I was trying to change the negative to a positive, there was a true or false scenario right above it. If specific applications where applicable, then this subprogram goes into action; for example, if John eats an apple, he will have one less apple; if John does not eat an apple, then he will have the same amount of apples. The true or false is reliant on if John ate the apple if he didn't, then nothing happens, but if he does, then the "subprogram" goes into action, in this case, he has one less apple, or FALSE = NOTHING, TRUE = (APPLES-1). The problem was that the sub-program is by default set to false, which is essentially an on/off switch for this whole section of the post-processor. And all I had to do was rewrite the FALSE into TRUE.
Once the post-processor was complete, I re-ran the facing toolpaths on the stock, and this time it went to the right locations and cut in the spot as programmed. I then measured the thickness of the stock (faced the front and back, should have been precisely 1.5") and found it to be four thou undersized (1.496"), which scared me quite a bit. I discussed it with my boss, and after thinking it over, I realized when I probed the tool height, I forgot that you needed to set the tool diameter to ensure that it was measuring the tip of the flutes and not the center of the tool. Because the inside of the endmill I was using had a cone-shaped dip in the center, it matched perfectly with the chamfer on the edge of the tool probe, thus measuring the tool lower than it would if it was only touching the very tip of the flutes. I re-probed the endmill and cut both faces again, and it came out +-0.0005," which is acceptable for this machine.