Virtual Center Dimensions Different from Actual Dimensions

[mbsquires]

I created a project with an X dimension of 17.9.

After converting the toolpaths, saving the G code, and telling the pendant to use the virtual center, the dimensions for the virtual center have changed to 16 (and change). They Y axis appears unaffected. When I air cut the project, it seems to cut in the correct places - but my question is this:

Why are the dimensions different?

TIA,
mbs

[ohiolyons]

You are going to have to provide additional info otherwise we are guessing.

What machine do you have? This sounds like a machine specific issue, based on info provided.

Could you post the file?

Vectric software doesn't use a virtual center, could you explain what you think this is?

[adze_cnc]

Three things:

1. you say :virtual centre” do you mean “virtual zero”?
2. if you meant “virtual zero” is your spoilboard that warped the you actually need to use the feature? If your spoilboard is ice and flat the feature is kind of pointless.
3. you say the job size is 17.9. Do you cut all the way out to the 17.9 or perhaps to just 16?

I expect the "virtual zero” is looking only for the distances your job encompasses. It can’t know that you set the job size to 17.9 in the VCarve software.

[mbsquires]

Yes, I meant virtual zero. No, my spoilboard is near perfect, and I usually don't use this "feature", but this project I elected to use the center of the material instead of the left corner as the reference point. I don't normally map the corners, I ignore the file specifics and go straight to cutting, but this time I noticed that the dimensions were different and I don't understand why that would be if it's reading the G code (which in the header does show the correct dimensions).

I have a Shark HD510. I'd like to upload the file, but apparently a 26mb crv file is "too large" to add as an attachment.

Re: adze_cnc, Q3: that's interesting. I didn't think to look at the difference between the edge of the workpiece and the sum of the difference between the two objects at the edge and the total X dimension. The top edge of the 3d model and the top of the project is .515". Actual project dimensions are 17.9375 x 7.3125. Virtual Zero dimensions are 16.94 x 6.31. So, basically, it's an inch difference, or 1/2" all the way around. Maybe that's what's happening, but that would only work if there is some rounding going on.

Thoughts?
p.s. I did attach a rendering of the project, just not the crv file (again, too large to post).

[sharkcutup]

I am not at CNC computer so working from my brain memory, I believe there is a setting in the Virtual Zero Preferences that can be set/changed to edge/boundary or to an arbitrary inside location within the project boundary. Check that out.

Based on the five points or with unlimited (Virtual Zero) points taken the Virtual Zero program creates a level plane and adjusts the g-code in relations to that plane prior to running the g-code. I use it often. It works well for me and my CNC projects. Just rarely ever change any of the Virtual Zero Preferences. Once there set there really is no need to change.

Sharkcutup

[Adrian]

I ignore the file specifics and go straight to cutting, but this time I noticed that the dimensions were different and I don't understand why that would be if it's reading the G code (which in the header does show the correct dimensions).

The dimensions in the header code are just text variables linked to the actual job dimensions for humans to read. Controller software usually looks at the extent of XYZ moves to work out the extent of the material being used.

For example if I create a 10" square piece of material and then cut a 6" circle centred on it my ShopBot will show a piece of material that is 6" plus the diameter of the tool in the preview. I would think the virtual zero is working in a similar way.

[scotttarnor]

Sharkcutup was correct about an offset in the setup, PNG from the manual.

[Tex_Lawrence]

Sharkcutup was correct about an offset in the setup, PNG from the manual.
virtual zero.png

Scott, is it possible to provide the page links that your PNG obscures?

[scotttarnor]

Here is the link http://cncshark.com/downloads/Ready2Con ... Manual.pdf