Possible machine overheating ???

[SeymourDumore]

Guys, sanity check please ...
I am running a program that has ran hundreds of times.
In fact it ran perfectly just yesterday.

Today, I've got 2 parts one after the other with unexplainable gouges and a .02 - .03 deviation in a Z-depth of a feature.
It is a 1 hour long purely 3D program with two simple 2D cuts at the very end.
The 3D portion is choppy as hell on some portions of the part, while perfectly smooth on the other portions.
Also, the 2 cuts of the 2D features are basically just a small wrench flats on two sides of the part, both should be at the very same depth.
And yet, one comes out .02 deeper than programmed, the other is .03 deeper!

There are no errors on the machine whatsoever, no anomalies of any kind displayed.
All I know is that it is pretty hot here today ( 85F ) and .... well, I know nothing else and can't think of anything else...

This is a 2007 vintage VF4.

Can this possibly be temperature related?

 

[RoundHouse M&F]

encoder? the 06 vf6-50 where i used to work had the set screw on the pulley attached to the spindle encoder back out ever so slightly to where it just wiggled back and forth on the shaft. spinning a drill/endmill one direction and you would never know it, go to tap and at the end of the tap cycle where it would orient in reverse instead and it would cause the drive dogs to be 15-30 degrees off and jam the atc arm (and break small taps).

or it could be temp related, same shop had a mazak sqt18ms (caxis lathe). the board on the spindle pack that controlled caxis movement and thread advancement would partially go out when it would get hot. it would start losing degrees as it rotated ( tell it to move 360 and it would actually move 270 but read correct on the control), it never messed with the threading when it got hot whitch was wierd but set a fan to blow on the motor and it would run no problem.

 

[SeymourDumore]

Ok, I've found the problem.
My problem is my own stupid ignorance, brought on by age, and Murphy.
If it worked before, it should work the same again.
You make a small change, well, it's small enough, so just ignore it, keep shit as it was ....

I did make a small change to my fixture. Small enough to use nothing but a puny 1/4" endmill to do it.
Problem was that the 1/4" EM had a fucking .03 corner radius on it !!!
Hence the deviation.

Moral of the post: Murphy is always always watching!!!

Fuck Murphy!!!