Blobs and holes on outer perimeter

Hello guys,
I recently build myself a CoreXY Printer with the Name Hypercube which was designed by Tech2C from Australia. The printer is working great but I got a print defect which I am not able to eliminate.

Printer: CoreXY
Slicer: Simplify3D
Filament: PLA and PETG tested
Object: 3DBenchy
Basic Settings: 0,2mm Layer, Infill 20% 200°C PLA; 240°C PETG, 60mm/s Printspeed, 150mm/s Movementspeed, Retract 5mm (Bowden), Retractspeed 50mm/s

As you can see in the pictures I get little holes and blobs in my outer perimeters. I tried nearly everything that was coming into my mind to eliminate the problem but I had little to no succes on that mission. Here are the paramteters which I allready tried:
- Retract from 0 - 10mm tested with little to no influence
- Retractspeed from 20 - 150mm/s
- Extra Restart distance -0,5mm - +0,5mm tested
- Extrusion multiplier from 0,9 - 1
- Belts loosened / Belts tightened
- Extruder is calibrated to 99,9%
- Hotend Extrudes fine
- Slicer changed from S3D to Cura same effects
- Coast at End 0,2mm-0,5mm
- Wipe Movement 5mm
- Different Layer heights (obviously the problem is more visible at 0,3mm layers but it still exists at lower heights its just harder to see)

So I tried nearly everything thats coming into my mind and I dont really know what to try next. I printed about 30 Benchys to get over the problem and I read through many forums and articles. It seems like I cant get rid of these blobs and holes.
What I discovered while printing is that the hole or blob is created on every layer change. When the extruder stops its leaving a little blob left. These blobs are not always on the outer perimeter, sometimes on the second. And it seems like if the blob is on the second outer perimeter the outer perimeter is no able to lay flat and is creating a hole. Pretty hard to discribe in words sry guys.

I am happy for every idea and solution for my problem

Christian

Your problem isnt in the slicer but in your printer, most likely is the bowden system you are using. You need to increase the extruder torque, reduce the lenght of the tube and also probably use a tube with an smaller inner diameter, the less your filament can flex or snake inside the tube the better.

You can try to increase the extruder feedrate to see if helps, also get rid of any wipe, restart and coasting settings in S3D, those settings works good on a direct drive but not on bowden.

Quote
ggherbaz
Your problem isnt in the slicer but in your printer, most likely is the bowden system you are using. You need to increase the extruder torque, reduce the lenght of the tube and also probably use a tube with an smaller inner diameter, the less your filament can flex or snake inside the tube the better.

You can try to increase the extruder feedrate to see if helps, also get rid of any wipe, restart and coasting settings in S3D, those settings works good on a direct drive but not on bowden.

Thank you for your answer!

My bowden setup consist of a Greg Wades Type Extruder with bowden fitting. So the torque shouldnt be a problem due to the gears. The bowden tube is allready short enough so that I can reach all corners of the printer. A shorter tube would result in stress on the printhead. I am using pretty standard China PTFE tubing which is used by many people and I cant really imagine that this is whats causing the issue.

I think I will just try another type of extruder and use a fresh bowden tubing. I will see if the results change or if I get the same problems.

But thanks for specifing my problem