HAAS G28 servo fault warning

I thought I'd post a peculiar issue I've come across. It's repeatable and resulted in a broken countersink.

If you do a G28 Z0. Y0. at the end of your program, to send the table front and center, the spindle will crash into the table.

It appears that if you attempt to do a YZ rapid, this overloads the power supply and causes a Z axis overload fault, which sends the spindle towards the table.

This is on a DC servo machine, but I thought I'd mention this, since I noticed in the BobCAD 20.5 post I have they have *2* separate lines that read:

G28 Z0.
G20 Y0.

Which indicates to me that they encountered this problem once.

I haven't bothered to throw a 2 channel scope on there yet to see what the bus voltages are when this is attempted, but I suspect the Z drive is backfeeding the Y drive and the drive is faulting because if undervoltage.

Perry, I'm willing to bet just about anything that if there is anyone out there who has ever experienced such incident, they've all immediately called Haas and had the problem rectified.
The Haas ( DC brush or brusless, DC drive or vector ) will guaranteed to be able to travel all 5 axis ( including A and B ) in one move, regardless of rapid or not.
If I'm correct, G28 Z0 will first rapid to Z0, and then rapid to Z-home.
Ditto for G28 Y0.
I always and only use G00 G53 Z0, so not too sure, but I believe the useage of G28 to send the axis home directly, without intermediate move is done by:
G28 G91 Z0
Of course, you can use:
G00 G91 Y0 Z0
to send both axis home at the same time.

And no, the separate lines of G28 in BobCAD ( Or anyCAM for that matter ) is done so to reduce a chance of the tool rapiding through the clamps when moving in the Y direction.
First send Z home, then move however you want to in X and Y.


I think your servo fault error is signaling the sudden death of your consecutive countersinks.