Spoilboard surface settings

Hi guys, trying to wrap my head around the whole feeds/speeds/stepover tool settings.

I’m trying to surface my spoilboard (3/4" MDF) with this bit:

You can see that when I separately run a rectangle around the perimeter, the finish is perfect. Using the same bit/settings, when I try to pocket out, there are a couple things I notice. I stopped the job and what you see is only during the first pass (so -1mm on the Z):

  1. The upper left side (MDF is uneven and this area is deeper), the bit is just skimming the surface and it looks like it is burning.

  2. The right side has noticeable rings. This would be an issue with my stepover setting?

Both of these issues are easily solved with a palm sander and light sanding with 80-grit, not the ideal solution :slight_smile:

Here is a photo of my issue, my setup in Estlcam and what the toolpath looks like in CNCjs.

Thank you for any help with understanding the tool settings – or something else I may be misunderstanding/doing wrong!

After reading up on similar posts, I see my issue is probably just tramming/deflection.

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The wider the cutting tool, the more sensitive it is to that. I have the same bit. Reduce the stepover, and probably speed, and you’ll get better results

Thanks Dan, I did try increasing the stepover to 75% and that didn’t help. Also tried changing to linear pocket (no difference in finish). I ended up just sanding away the lines, which didn’t take long.

After I check my tramming I’ll try surfacing a scrap piece of MDF and reduce my stepover. I’m using a DW660, so my speed is fixed.