We are using a BWO CNC 900 control on a 5 axis Maka CR27T. I have an intermittent problem with an axis trying to reach a position outside of the machine limits. If in X or Y, this travels at feed, if the position is within the limits of the machine, it will then feed to its next position once this has been reached. If outside of machine limits it will go into software limits of course. This usually results in scrapping the part it is cutting, or at best needing some level of rework. Unfortunately, if it happens in Z axis it usually results in hitting the table and breaking the tool, or shutting off due to overload. I am 100% it is not incorrect programming, this has been proven by rerunning the same program, and the machine cutting ok to the end.

We have removed and reseated control cards, cnc cards, drive cards, checked as many connections as we can find, in particular earth connections. I think we can discount the drive cards ,as the axes concerned are X,Y and Z, so it must be something common to all axes. I should add, other than positioning A and B axes after the toolchange, these are not used during cutting.

Any suggestions of what to look at next would be gratefully received, I am running out of things to check, and where to look.