perimeter problem

Someone seen this before....? Print is rather well and sudden it starts to print very odd.
These two parts are printed on two different printers(same type, reprap)
One is printed with a 0.5 nozzle and .38 layer, the other was done using a .35 nozzle and .24 layer.
All is done in PLA. Had no problem before.

Second problem I have is that vertical ripple, best seen in the right part.

Have you tired to slice it with another slicer?

I'm not sure about the first issue, it could be a few things:
- Temperature - look closely at the hot-end temp and see if it is stable throughout the print.
- Temperature - perhaps that particular filament likes a different temperature.
- Speed - you may need to slow it down.
- Layer height is a bit high - OK if you are going slow, but you may be exceeding the hot-end's max extrude rate at that temp
- Fan - since you are printing PLA you should have a fan blowing on the print - but not cooling the hot end.
- Clog? Maybe try the cold pull method.
- Clogged extruder gear? Is it picking up swarf in the gear?
- Always check that that the extruder gear is not slipping on the stepper (grind a flat on the shaft, etc.)
- Driver overheating or under-powered - if it's skipping back or stalling then that's a problem.

The second issue - those vertical lines. That's called Ringing, and it is caused by resonant flexing in the machine when it takes a sharp corner too fast.

There are a few settings for this:
- Acceleration (Firmware) - you could lower the printing acceleration.

- Jerk/Junction Deviation (Firmware) - this controls how much more the printer slows down for tighter corners. A lower number causes it to slow down more in tighter corners. At angles below about 18 degrees it slows to the "minimum planner speed" which may default to 0. This may be called something else in your firmware (I use Smoothie). At angles over 161 degrees Jerk/Junction Deviation is not used.The default Jerk number varies according to your firmware.

Acceleration: Slic3r - Print Settings, Acceleration Control. You can set the acceleration separately for most kinds of features.

Note that you can also set these parameters yourself by inserting gcode, either in the beginning gcode, or where appropriate.

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
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