VCarve Moulding Toolpath mills unwanted strip off surface, why?
Hey everyone,
I am working on a frame in oak (20 mm) using VCarve Pro 12.5 and a BZT router. I'm using the Moulding Toolpath to cut a shadow gap/cove profile along the inner opening. I'm running into a weird issue and I wonder if anyone has an idea where it's coming from and how to solve or avoid it.
The problem:
The machine was milling ~2 mm off the top surface of the frame along the inner edge. I marked parts of the area I am talking about with two black lines in the photo. As you can see this part is milled off all around the inner edge. The cove shape itself is fine, it's just this unwanted horizontal strip being cut into the surface at the top of the cove.
What "fixed" it:
I set "Gap Above Toolpath" to -0.2 mm, which got rid of the surface cut. But the tool is still passing over this area, it's just not touching the wood anymore as it's slightly higher than the surface.
New problem:
The top edge of the cove is now rougher than before.
I've got two questions:
Is negative Gap Above the right fix here or is there a better approach?
Why is the toolpath cutting into the surface at all when the profile vector doesn't extend onto it? Is this just how the Moulding Toolpath behaves with open vectors?
Here's a summary of what I'm using:
- VCarve Pro 12.5
- BZT CNC router
- 20 mm oak plate
- Drive rail: inner rectangle, 100 × 100 mm, 4 mm corner radius
- Profile: open bezier cove curve, 5 mm wide × 4.8 mm deep, top node has vertical tangent
- Tool: Ball Nose 6 mm
- Gap Below Toolpath: 13.0 mm, Cut Depth: 5.0 mm
- Vary Stepover: on
Please let me know if there's anything missing that's important. Thanks in advance!