Z Axis seems to be slipping

[pjames]

So the other day I woke up and the RichAuto controller wouldn't startup, so I did what Axiom said and installed their firmware. Ever since then, my Z Axis seems to slip when performing different cuts. It won't screw up during a toolpath, but will change between toolpaths. So basically when I make a few cuts, then check the Z Axis (zeroed on the workpiece itself), it is far off from a zero reading.

Any suggestions or advice??

[aluomala]

Check the z-axis coupler (remove the plastic cover) and see if the coupler is broken or if the set-screws have come lose). It's a relatively common occurence, and having spare couplers on hand is a good way to maintain your sanity (if a coupler breaks, you are dead in the water, and depending on where you live (I'm in Canada) it can take a few days or weeks to get a new coupler from Axiom. I ordered 5 of them from Amazon, and have only had to use one spare (knock on wood!) in the 3 years or so of owning my 2 Axiom machines.

If that isn't the issue, check your collet to see if the bit is slipping out (put a Sharpie line on the bit where it meets the end of the collet). If dust/chips get into the collet (from not cleaning it often) the collet can't grip the bit and it will slowly get pulled out while machining, and that will cause the bit to cut deeper into the wood. If you're lucky, the bit gets pushed up into the collet. Lucky in the sense that you don't ruin the project and/or bit, but obviously your carving won't have been done properly (cutting air instead of wood).

ANother possibilty is static discharge from dust collector (effecting the stepper motors, causing you to "lose steps"), so make sure machine/dust collector is grounded properly.

I have had all 3 of these things happen to me at different points, so those are the culprits that come to mind. There are likely more, but start with the most likely and work your way from there.

Allan

[pjames]

Yep, the coupler had come loose! Tightened it up and it seems to be doing better