Gaps in z-seam when printing stringing test tower

[Mechatron127 0]

Hi,

 

I'm busy this week setting up my printer after adding a second Z-spindle to my Ender 3Pro.

 

I modelled a stringing test tower and printed it a couple of times with no infill, no top layers and a single wall.

When putting the z-seam in the back (this is the front of the tower in the picture) I noticed one tower has gaps in z-seam.

 

 

 

I tried to solve this by lowering the print speed from 50mm/s to 40mm/s, increasing flow to 105% and 110%, z-hop on/off, prime from 0 to 1mm^3.

There seemed to be some improvement but no solution.

(The warping in the left bottom was caused by me pulling the print of the still hot bed as warping is, at this time, no issue)

 

After studying the tool path in the Cura slicer I noticed the difference in build up of the layer between the towers.

 

In the good tower the print head leaves the freshly deposited layer tangentailly in the same direction as the print direction, in the bad tower the print head leaves the freshly deposited layer also tangentially but after reversing 180degrees. Apperantly this caused too less material being deposited at the z-seam.

 

- Good z-seam location is the start position of the layer

- 1 is the tool head position just after the start of the layer

- 2 is the tool head position just before the end of the layer

- green arrow is the movement to the start of the next layer

 

The start of the red horizontal arrow to the left is the moment the tool head leaves the right tower.

The head of the red horizontal arrow is the start of the layer in the left tower.

The start of the green horizontal arrow is where the tool head reverses direction after the completion of the layer.

 

This issue doesn't occur, or isn't visible, when printing 2 perimeters.

 

Printing a single wall tower with random Z-seam location seems to solve the issue but the model looks very course then.

 

Is there a function in Cura or a WoW to solve this?

 

Material: PLA

Nozzle diameter: 0,4mm

Nozzle temp: 210degree centigrade

layer height: 0,2mm

 

 

 

[Mechatron127 0]

 

Adding some travel from the bad z-seam location to, in this case, the left would solve it I think.

I have no idea how to add this to the g-code, except by hand but in other models this migth be too difficult due to angles and a very large number of code lines.

 

[GregValiant 980]

Check your Outer Wall Wipe Distance (0.1 or 0.2 usually works OK) and make sure Coasting is turned off.  Retract at Layer Change and/or Retract Before Outer Wall may cause that as well.

I haven't seen anything like that with my Ender 3 Pro and so I'm thinking it might be a setting.

Edited March 4, 2022 by GregValiant

[Mechatron127 0]

Thanks! :)

 

Retract at layer change turned off solved the issue and now the printer produced a near perfect tower, very nice.

(This is right after pulling it from the bed, no post-processing/rework whatsoever)

 

This saved me a lot of money as I was about to order a Prusa mk3s+ in the hope to solve all issues.

 

Thanks again.

 

[GregValiant 980]

Well, there ya go.

I am not totally enamored with my E3Pro but after getting to know it and it's idiosyncrasies I've gotten it to work quite well.  The second part was Cura itself.  It is not a simple program to learn as there are a ton of options and some can interfere with others.

Taking the time to calibrate everything from the frame geometry through the e-step calibration, the belts, the wheels, axis angles, etc. pays dividends in the end.  Knowing how to read gcode, how to look at a model and know what it needs to print well, how to apply all the Cura settings to get what you want out of the print...a lot of stuff goes into getting good prints out of any printer whether it's your Ender, a Prusa, an Ultimaker, or my own design the (yet-to-be-released) "Harry Potter 3d Platinum Pro XL Extended Cabriolet w/Easy Button".

[Mechatron127 0]

 

Now I have printed a single wall "cube" and a CHEP-cube also.

 

I'm so content with the current setup that I have ordered a second Ender 3Pro with all the updates I have on my first one plus a Micro Swiss full metal print head today. This will be my "hot printer" for PETG and LW-PLA to print parts for my RC planes.

 

 

[GregValiant 980]

As you learned from the first one - Assume that nothing is put together correctly from the factory and you will be good to go.

The all-metal hot end is a good idea.  So is a more robust layer cooling fan.  The 4010 blower that comes stock is weak to say the least.  You don't need one of those gigantic dual blower monstrosities but a good ball bearing 5010 is much better than the stock blower.