VF3 5axis probing problems

[gpcoe]

I'm doing a job on a VF3 5 axis trunion. Every face has true position requirements of .002" to the top (vertical position) face. One Datum is a small .062 hole specified at a certain angle from another datum and all the faces are tied into that angle. The part is loaded already roughed and finished turned on a lathe. We are probing every face for the WPCs. I've had problems all along with floating dimensions and narrowed it down to poor probe calibration due to inaccurate out of round hole sizing. I have to use vectoring to find circular center due to gaps due to the parts features. Now that the diameter is dialed in correctly I'm now able to Indicate the part in by hand and have repeatable findings within .0002" or better on either axis with the probe. However, when checked post -machining, the .062 datum hole is dead true on the x-axis +/-.0001", but the Y axis measurements are -.001 repeated between two parts both indicated, then probed with matching results. Unfortunately, the angular displacement from this throws off true position results on the other faces. Tomorrow I will be checking backlash on the machine. All the features on that face are shifted that direction, but that hole is the important part. For reference, the hole is being drilled undersized then circ interped with a 1/32 EM to .002" undersized to eliminate drill wander and then reamed to .062. When checked on a CNC CMM machine with scanning the hole has .0001" deviation on diameter form (No burs interfering with measurement). I verified this on a manual CMM with the same results. In other words the hole it's self is perfect. I've watched the variable and offset pages to ensure nothing is changing during machining. Every other feature on that face aligns perfectly in relation to the hole, but everything is -.001 south on the Y axis. The other faces (all 90deg to each other, no fancy angles) check out about .0003-.0007 true position when not related to the .062 hole. In other words, they're being machined accurately enough from the probing. Other than backlash, is there something I'm missing. I'd expect deviation part to part, but not .001 as indicated and probed true. Fixturing was double checked to ensure True Vertical/Horizontal positions and trammed to the spindle and verified by rotating the B axis with equal measurements. Any ideas or suggestions would be much appretiated.

Thanks

Greg


Edit: Forgot to mention...I'm cutting 2024 aluminum (T4 I believe)

[Excelmachine]

You might want to post this in the Haas Mill forum as this is the lathe section, you might get more responses. Good luck.

[gpcoe]

Well lathe section it is. Sorry to waste bandwidth.

Thanks