x axis not to drawn dimension

[bentfab]

Howdy. I've been using Cut 3D for a few years to make art, I use cnc to get me 90% there then do the rest by hand adding details and mods as I go. Over the weekend I was making some pieces much smaller than I normally do and realized that the actual part made by cnc was consistently about .1" smaller in the x axis than what I had drawn. The y and z dimensions were also a bit smaller, but only by a few hundredths, which is acceptable.

These 3D cut parts are supposed to match up with some 2D cut pieces which came out as drawn. I checked some older pieces I had made and they appeared to also be off about .1" on the x axis. But these are much bigger pieces and they don't have to fit anything so I never noticed.

I draw in Rhino 5 and export as a stl. I don't think it's my machine because 2D cuts are spot on. Have I inadvertently changed a setting in Cut3D, or never set it up correctly? Is this just the way it is and I need to stretch all my drawings by .1" x axis before I export?

Any help appreciated.

[Leo]

Have you ever calibrated your machine for "steps per inch" on all three axis's?

[bentfab]

If my machine was off wouldn't 2D cuts be off as well as 3D?

[adze_cnc]

Instead of exporting the model as an STL file could you export it as a Rhino version 4 file and try that instead?

You'll have to tell Rhino that yes, indeed, you want to use version 4 instead of 5. (Honestly McNeel, can you not trust that I know what I'm doing instead of forcing me to verify that I do want a 4.0 file?)

Steven

[bentfab]

I'll give it a try next time.

[bentfab]

Will rhino 4 export directly to Cut3D

[Leo]

If my machine was off wouldn't 2D cuts be off as well as 3D?

Yes it would.

[adze_cnc]

Will rhino 4 export directly to Cut3D

My apologies. Rhino v4 files import fine into VCarve so I suspected Cut3D would also handle them. I was in error.

You could try exporting an OBJ file using NURBS curves rather than a polygon mesh. That I know works.

Steven

[bentfab]

I just tried obj with nurbs, but it wont load in Cut3D

[adze_cnc]

OBJ with NURBS (using whatever defaults Rhino v5 uses) loads fine in my Cut3D v1.11. So I an at a loss. Since VCarve added 3D toolpaths I haven't needed Cut3D though.

My reasoning for wanting to try either Rhino v4 or OBJ with NURBS was to keep the surfaces as mathematical entities as long as possible and to avoid the polygon mesh of STL files. Rhino files import nicely into VCarve.

I also thought that perhaps in the export and the import of the STL file some unknown scaling was happening. I have received exported STL files from Solidworks that needed to be scaled by 2.5 to get them to actual size. I originally thought it was a mm vs inches problem but that would have meant scaling by 2.54. And the STL was in inches and supposedly exported at 1:1 scale. I never did figure that one out I just made it work.

[bentfab]

Yeah, my thoughts were also that there was some sort of scaling issue when converting files.

I'm still using VCarve6.5, maybe it's time I updated. I've been hesitant to try because when I bought V carve I was working with a company that doesn't exist anymore, so that email doesn't exist, so I have no way to prove I bought it.

Thanks for your help.