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Getting the first layer right

A project log for Wire 3D Printer

A 3D printer for printing with welding wire

Dominik MeffertDominik Meffert 04/10/2020 at 18:061 Comment

Even if the hardware works as it should...without the right settings printing is impossible.

I will try to figure out the right settings to get the first layer right every time on every object.

If I can get a good first layer, the printing progress is a step closer to success.

I think I should start documenting the failed attempts...

For this I used the default Simplify3D settings. I only changed the global Z offset to 2mm and the extrusion multiplier to x5.

The print failed due to the travel speed of 4800mm/min was to fast for the T8 threaded rods. Because it was the first layer it was just half the speed (first layer speed default setting: 50%). The print would have failed anyway because of the 0.2mm layer height which doesn't match to a x5 extrusion multiplier.

It sounds strange but that was the best print for the last two weeks or so :)

I think that the speed has made the difference. For the last weeks I tried printing with less speed what has lead to nothing but failed prints....

So it should be the best to print not slower than needed.

In this video I used the Simplify3D default settings but changed some settings: 

Nozzle Diameter 0.8mm 

Extrusion Width 0.8mm 

Global Z Offset 2mm

(Layer Height 0.2mm) 

Extrusion Multiplier x5,5

Default Printing Speed 2400mm/min

First Layer Speed 100%

First Layer Hight 100%

First Layer Width 100%

Temperature 0°C 

Cooling Layer 1 45%

Startcode: 

M106 P0 S70 (For Probing)

G28 

M106 P0 S120 (For Heating)

It seems like this settings are good for the first layer. I could print the same object multiple times successfully. But unfortunately it's only the first layer that works out. The second layer ends up in stubs of melted wire. That happens because the wire melts, but instead of fusing together with the underlaying layer, the layer next to it and also the "extruded" wire it breaks and looses the connection with the buildplate, what creates a stub. This happens every millimeter and leads to a brittle layer. 

At the moment I don't know what I could do against this behavior but maybe I will find it out.....

Discussions

Krzysztof wrote 04/11/2020 at 09:14 point

> This happens every millimeter and leads to a brittle layer.

It's like it melts and solidifies before another portion of wire melts... You probably already know what I want to suggest... MORE SPEED. You could offset speed with lower power, so that wire is not melting away from wire and stays "gooey", but that heat will still creep up into your nozzle. Suggestion on how to get your power level right: start with clean buildplate, remove feeding mechanism, try to print some big cube so that you have enough time for tests, set extrusion width to 1.5 or 2mm, then when printhead is moving, gently press wire and ramp up power until wire is melting properly. If you mark wire with marker about every cm or so, you could film the process and you would have exact feeding speed, or measure your extruded width and slicer will calculate it as needed.

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