Carving air instead of material. The program is running in reverse!

Here’s something odd. I’m using Aspire 9.5 and installed the test 5 post processor. When I run my project, instead of the bit going up, over and down, then start carving. It’s carving in reverse. The bit goes down, across, then it rises up above the wood and starts carving the air above… ain’t that something? And I can’t figure out what to do to fix it.

Flip your z axis plug, or see if there is a setting to reverse the z.

1 Like

When you move the z axis by lcd or control software, does it move correctly? If you give it a +z command, does it go up? If not, flip the z plug. If it does move correctly, make sure you have the job start point set correctly. You may have it set to the spoilboard surface as start.

1 Like

Finally. it works. Thanks.


Plus was going down. Flipped the plug and it works. Thanks


Looks like you found a solution, but for the folks that run into this in the future there’s a software fix that can be used as well.

In the Marlin file in Arduino IDE, you can also change

#define INVERT_Z_DIR

to the opposite of whatever it is currently.

1 Like

Yeah, I had taken my cables off and reversed them when I reinserted them. Brainfart. Do you know a way to get it to go straight to the same XYZ 000 location (home) every time? I have to manually move the gantry and shut off, then restart so the machine knows my 000 is my left bottom/front corner. It would be great if the software knew where that single point to start from was located.

I drilled a hole for my home and then move all axis until they line up at that spot. Still…

Thanks for sharing the code bro. That’s good to know.

g92 x0 y0 z0 set the current position to 0, 0, 0

Hi Bill,

Is that what I put in my code at the beginning? I’m not sure how to use this. Sorry.

I do know how to access the gcode in ESTLCam if that helps. Do I move my x,y, and z to the place I want to be 000, then, in my code for what I’m making, enter this code and the three axes all return to the home position every time? Or unless I shut the machine off? I hope that’s clear.


Hey Mike. If you put that code at the start of your gcode, wherever you hit go, will automagically become 0. It will stay 0 until you issue another G92 command, or power cycle the board. Makes forgot to set zero errors go away that way. Nothing worse than getting your endmill where you want it, then hitting go, and watching it zip half way across the workpiece before starting. So far I’ve not had it start in the wrong place that’s recoverable… :lol:


Perfect. That makes it possible to have repeatability instead of cycling through and restarting. Thanks Barry, and Bill

Yeah, you could manually set it in Repetier-Host, but it’s much harder to forget if you have it generated at the start of your gcode. :slight_smile:

I agree. I use Aspire for my carving and I can add it in there somewhere. I have to figure it out again. To be able to lock a start point and reproduce a part is what CNC is all about.

Probably add it to the post processor.

Can I go in and change that on Test 5 PP?