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

[papajag]

I am struggling with Virtual Zero Unlimited at times. It may work perfectly on one project and then go rogue on another one. I had a workpiece that was approximately 10"x9" and had to set 22 points to get it to cut properly. Any fewer and it would cut erratically. Also, on some pieces, even when I take great care to get my material height just right with a micrometer, when I trying to set points in VZU, it will drive the bit into the material. I ruined a piece of good wood before I could cancel it. I am not sure why sometimes the bit will move up several inches between each point capture and at other times it moves up a half inch and then drives into the wood. I have tried everything I can think of including re-loading the software. Any suggestions would be greatly appreciated.

[scotttarnor]

I have not seen the erratic behavior you are seeing. I think you would be better off contacting Nextwave for assistance with this as virtual zero is their product, they have provided excellent service the few times I needed it.
support@nextwavecnc.com
(419) 318-4822

[SteveNelson46]

Make sure your z-zero setting in the software is set to the same value in your controller. If you set one to zero to the material bottom and the other to the material top you can experience similar problems.

[sharkcutup]

I have an earlier Version of the Virtual Zero Software it only can take 5 points (4 Corners, 1 Center) of area that is to be machined with the particular bit installed at the time.

I use it a lot due to 2 reasons (1 major, 1 minor) and I have also learned with experience using it when it is really not needed

1.) Major Reason -- I do not level plane my spoil board anymore which had created a level plane to the Gantry/Router Assy.
I did when I first got my CNC Machine but after using Virtual Zero and learning its capabilities I decide when time came to replacing the spoil board not to surface it again. The Virtual Zero has as I have learned can compensate for that too!!!
2.) Minor Reason -- of course material boards are not always truly flat. They tend to do have some warping and or cupping at times.

Of course though most all of my projects are done in wood so tolerances are really not an issue. Now if I was doing metal work or Engravings things would be quite different.

Here is a Sign I have just recently (Sunday) carved an Example of Using Virtual Zero Exclusively on a Project!

Sharkcutup

[papajag]

Thanks to all for your suggestions. I think I may have to go to NextWave for some advice on this too. Thanks for that suggestion. Have a great carving day guys.