View Full Version : xyz orientation issue

05-10-2018, 10:50 AM

Just did my first cut with the new cnc and was surprised to see the orientation and the image mirrored, as in diagram 2. Whereas I expected it to cut as in diagram 1. Its as if the machine thinks its underneath cutting up..or something?

As I stand at the front of the machine I wish to have it home to front left. I want forward and back to be the X (+ A ), I want left to right to be Y axis and Z up and down. The keyboard jog arrows suggest that what Mach3 thinks its doing, (however the table view could be as if your underneath the table looking up). I made up a quick file in Vectric in the aspect and expectation it would cut in the orientation as in diagram 1. However it descided to cut as in diagram 2 which rather threw me.

I use Mach3 software and Vectric Aspire CAM, where should I start to troubleshoot this?



05-10-2018, 11:43 AM
Left to right is the X axis. Better to learn that basic principle otherwise you will confuse yourself and everybody else.

05-10-2018, 12:12 PM
Left to right is the X axis. Better to learn that basic principle otherwise you will confuse yourself and everybody else.

Yes indeed that is the standard and would be logical to use. However for some reason I used x as left to right in the first build and it just was just easier to continue that into this current build. It would I appreciate help in the problem solving to stick to the Y left to right and it looks like i'm getting caught out this time. However i'm just wondering if I can change software setting and not rewire it.

Its so close to being ready...Hmmm :)


05-10-2018, 12:41 PM
Rewiring at this stage is easy... I think it is better to do it right and fix that now. Yes, there are ways of fixing it even in Mach3 configurations, but why?

05-10-2018, 01:02 PM
I can understand the need to rewire but would it address the file mirroring, as in diagram image 2?

05-10-2018, 05:08 PM
As A_Camera says, convention standing in front of the machine, is X is right to left, with Y being forward/backwards, which typically means the longest axis is X. However on routers, it can be either, and I wouldn't say any particular way is right or wrong, as long as you know which is which.

Moving X or Y in the positive direction should move the spindle in the positive direction for the cartesian coordinate system relative to the work area, with the origin being in the bottom left (same as the home point on your top diagram).
So standing in front of the machine, on a moving gantry/spindle machine (aka a typical router), the head would move away from you/right for positive moves, or with a moving table (aka a typical mill) the table would move left/towards you.

If that is working correctly, then it sounds like Aspire is flipping the g-code for some reason. It's usually worth running one of the supplied controller example g-code files to see if things are moving in the correct direction (the classic Mach 3 test is the roadrunner file, which should be in the mach3 installation directory somewhere - strap a pen to your spindle, tape a bit paper to the bed, and see what happens).

It's worth noting the home point is actually irrelevant in terms of movement. Mach can be programmed so the home point is in whatever location you'd like. You could have it bang in the middle of the bed if you want, but it's far more useful to have it at a back corner to keep the spindle/gantry out the way for loading.

05-10-2018, 05:44 PM
If an axis is being flipped then you need to reverse the polarity of one of the stepper windings for that axis. This is not a major rewire.

You do not mention which post processor you use, this <might> be relevant.

You should also be able to test this by jogging with the keyboard arrows and Page up/ Page down. It makes more sense for those to jog in the correct directions i.e X left and right, Y forward and back, Z up and down.

You will save yourself a lot of confusion and probably avoid spoiled work or broken tools.

05-10-2018, 09:41 PM
Thanks for eveyone’s thoughts.

I’ve used Aspire for the last few years and i’ve not changed any of the setting recently so its less likely to be a CAM and post processor issue. I even ran a piece of g-code written for my first machine and it inverted the cut path.

With this build I have copied some of the elements of my first build. The first build homed in the back left corner and ran forwards. It too had the x&y the wrong way round but i just got used to it and didn’t invert cut paths. This new machine has been built to home front left BUT with the intention of having the g-code also run from the back left corner like the first machine. Running a test bit of g-code shows me the machine is mirroring the file and reading another forum discussion leads me to think the machine is therefor running backwards. The keyboard buttons however work exactly the same as the first machine but it never inverted g-code like this machine so thats a tad confusing.

Maybe i’m just missing something really basic that i’ve overlooked in the Mach3 setup, Dir LowActive settings or something. Are there software setting I can change before I consider reversing the polarity of stepper windings?