[garyalan59]

Just got VCarve Pro today and have ru ino a difficulty.I created a logo to be engraved on the barrel of a baseball bat. When I ran the program, the text was mirror-image. How do I correct this so the people who are getting it won't have to hold it up to a mirror to read it?

Gary

[ger21]

Just a guess, but maybe you have the rotation direction of your rotary axis backwards? Or perhaps the linear direction of the rotary axis is backwards?

[garyalan59]

The G-code output contains this line:

G70 G91.1

I know what the G70 does, but I'm unfamiliar with G91.1, other than it sets incremental IJK mode. What does that mean? Is G91.1 a persistent command, or does it need to be invoked every time you want to use it? What would be the effect of changing this to G91? Alternatively, what would be the effect of going to G90 or G90.1?

Gary

[ger21]

You're talking about two different things.
G90 and G91 are absolute and incremental distance mode.
G90.1 and G91.1 are absolute and incremental IJ mode, which specifies the center of arcs. I don't believe there are any arcs in rotary code from V Carve Pro, so the G91.1 will have no effect. It's certainly not the problem.

G91.1 is included in all Vectric posts to make sure that Mach3 is in the correct mode if there are any arcs in the code.

Whenever someone has an issue with mirroring in normal 3 axis work, it's usually (always?) because the machine is set up incorrectly.
I'm guessing the same here.
Is it mirrored left to right, or top to bottom?

Which axis is the rotary aligned with?

[garyalan59]

Found the problem. I thought (since I'd never seen it) that the fault was with G91.1. In actuality, Y-to-A conversion (for wrapping y axis around cylinder) was performed backwards in the program. I confirmed this by exporting the X,A coordinates to Excel; the graph created was the exact mirror image that my machine carved. Changing the "polarity" of the A coordinates fixed the problem.

However, this is only a temporary fix. I still need to figure out why VCarve Pro output inverted coordinates.

[Greolt]

I am going to assume that because you posted about this on the Mach3 forum, that you are using Mach3.

The Post Processors that are provided by Vectric for wrapping toolpaths for Mach3, are written to turn the rotary axis the way that Mach3 expects.

I have given up arguing what is conventional direction. It does not really matter anyway.

Mach3 can visually represent a rotary toolpath (for A axis only) and the Vectric PPs are written to comply with this.

You have two options:

1. Reverse the direction of rotation of your A axis. Do this in menu/homing&limits/. Toggle the check mark in the reversed column for the A axis. This would be my preferred option.

2. Edit the post processor to output toolpaths to suit your axis direction as it is now.
To do this edit this line ROTARY_WRAP_X = "-A" to remove the "-"
This would make the visual toolpath view backwards in Mach3, but if you prefer it this way then it is up to you.

Greolt

[garyalan59]

Thank you. After thinking about this for a while, and recalling previous situations, I'm fairly certain that my A-axis rotation is reversed.