gCode anomaly - dead spot (UGS)

Hi - I’ve been having a bit of trouble lately with a strange issue. I’m creating raw gCode files with Fusion360 and sending them to the X-Carve using Universal gCode sender. More and more frequently, the machine has been hitting ‘dead spots’ whilst running through the drilling CAM process programmed in F360. It’s a simple down - up - move - repeat motion, but sometimes the bit will stay down and move to the next spot, cutting a huge ugly line completely through the wood.

I believe it’s an issue with Universal gCode Sender because when it happens, if I cancel the whole job and mount a fresh piece of wood, then send the same file over it, the dead spot won’t be there.

I suppose I’m just looking for anyone who has experienced this and can identify whether it’s a hardware issue or the gCode sender. If the latter, I’d really like to know what the best alternative is - I’ve seen a bunch but only spent time using UGS - I’m sending from OSX OS.

Any thoughts?

It sounds to me like you may be losing steps intermittently.

I doubt it’s a software issue, actually.
Intermittent issues like this can be a bear to locate, but are normally related to loose connections or broken wiring. More than likely, you have a ribbon cable or two loose inside the controller, or a loose wire on the stepper motors. The ribbon cables inside the controller are a bit of a bear to seat completely, and can easily fool you into thinking they are locked in, but wont be fully seated.
I had this same issue early on, and was absolutely certain everything was seated.
On the advice of others, I double checked, and sure enough, the cable ends were locked in, but not fully seated properly.


Sounds like Z loose step intermittently during retraction.
I would first of all check that all set screws are in place and secured, then verified good electrical connection on all 4 motor wires (Z motor wires)

There are other reasons why it resist retraction but those would be my first two get-to’s.


You know, it’s only ever the Z-axis, so I’ll start with that. I’ll put some contact cleaner on everything and see if it still happens. Thank you - definitely was expecting it to be software-related for some reason.

Check the grub screws that hold the pulley on the acme screw.