Divots at entry and exit

I am curios if anyone can tell me why my entry and exit points are not clean.

  • It does NOT appear to be an issue with the Gcode.

  • The problem is more pronounced toward the top of the workspace.

  • I watched it closely. The XY travel path is smooth. The notches are created AS it is plunging and retracting. Almost as if the bit is entering at an angle, yet once fully extended it cuts as expected.

Any advise or speculation is welcome. Many thanks. Ed

Hi, I guess flat endmills are not perfect tools for drilling…so going straight down too fast may cause vibrations.
I guess you could try reducing the z-axis feedrate, or use ‘ramped entry’ instead of vertical plunge (if your CAM-software have an option for that).

I don’t know which other CAM software support this, but I know KrabzCAM does…

Good luck :slight_smile:

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do your endmills have a continuous cutting surface on the bottom? If not (and
not all do), you can be in a situation where the bit can’t fully remove the
material when plunging directly and as a result it wobbles a bit on the part
that’s not cut (which moves it to where that does get cut)

As noted below some CAM software offers an option to avoid direct plunge cuts
and instead ramp down.

David Lang

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Hi there. Thank you for the replies, and sorry for the slow response on my part. Life does have a way of getting in the way of fun.

Your explanations make good sense, and I will make an attempt to see if reducing my plunge rate or ramping will correct the issue. Wobble makes sense. However, this also happens as the bit exits the cut, which leads me to think it could be something other than resistance to the cut that is causing the wobble.

I have had considerable trouble with the z-axis movements. The pin that takes the brunt of the force has broken more than once. Maybe not broken, but worn out, and at least once I have put it back together wrong. Anyway, I suspect that this may have more to do with the some worn out or bent part. Hopefully something easy like the bit. With that said, I will start with the plunge rate/ramp and hope the ‘exit issue’ is just part of it that I do not yet understand.

Again, thank you for your help. This forum has been a lifesaver.

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