Strange lines in some carvings

I’ve been running in to an occasional problem with lines showing up on my carvings. I’m still trying to troubleshoot where they could be coming from. Here’s a photo:
(this is a bronze casting from the original wood model carved on my x-carve)

There was actually another line just to the left of the one shown in this photo. Exactly parallel to this one and running the full length of the carving. For orientation, the line runs from top to bottom along the Y axis. But this makes me think it must be something wrong with the X axis for it to cause lines in the same direction like this (but maybe I’m not thinking about it correctly). The frustrating part is that it doesn’t happen often enough that I’ve found a solid trend yet. A few of the things I’ve made mental note of:

  • It can happen in any material
  • When lines appear, they’re always top to bottom on the carving
  • It only happens during finishing pass
  • The smaller the bits and the faster the speeds, the more likely it is to happen

Here’s another oddity…Until this carving, I always used “cut x only” in the Meshcam settings. Thinking it was an x axis problem, the carving in the photo above was made using the “cut x then cut y” setting (I figured that second y cut would eliminate any chance of the lines). But as can be seen, the lines still showed up. I’ve searched around for some solutions and the only thing I found was in another forum where somebody said this can be caused by debris getting in the rails or gumming up the axis wheels. I blew them out with an air compressor. Running my first carving since that photo above and waiting to see if it eliminates the problem.

Seems more like your Z-axis isn’t completely square to your table and it gets worse when you run it too fast. Try a large diameter flat bit and see if you get lines similar to these.

Sometime with metal if you don’t remove enough material on a pass this will happen. I kind of skates on top till the pressure is enough to plunge.

I have gotten these exact lines. It’s not all the time. And only with a tapered ball nose. I found a slight clicking sound in my Z axis. The clicking sound was the wheel sliding on the bearings. It was caused by an over sized shim inside the wheel. It measured 1.19mm instead of 1mm. It wouldn’t allow the bearings to seat properly “.19mm” gap inside the wheel. So every once in awhile it would shift throwing off the alignment just a tiny bit. Hence the line. I replaced it with a .93 mm shim and it allowed the bearings to seat all the way. No more click. And no more lines as of yet. Not completely sure if this was the cause. But it seems plausible and I haven’t seen them again. As of yet.

Not sure if you can see it. But up toward the top of the bread is the line.