Layer Adhesion Problems

I have a Prusa i3 Rework that I am building for a school project. I have been able to get it to print; however, my layer adhesion is suffering. There are gaps between the layers. How do I get the layers to bond better? Here are my printing settings: Black PLA at 220 C for the hotend and 65 C for the bed. I'm printing directly on glass. I'm not quite sure what speed I'm printing at. I didn't change any of Slicer's presets. Thank you for any help you can offer- Jacob

First off I would try lowering your print temprature. 210c should be as high as you go, I print between 192c and 201c.
If that does not help calibrate your extruder with this video.
Make sure your steps per mm are correct. on the Z axis.
Double check your bed level and Z offset.

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Prusa i3 Rework - Ramps 1.4 - E3d Lite6 - Full Graphic LCD Controller

Pla shrinks upon cooling, like most filaments do. There are a few factors that has influence on layer adhesion and delamination.

- the ratio of extrusion width and layer height should be about 1.2 as a minimum. So it should be wider than heigh. The wider it is, the more pressure is excerted, pressing the layers together.
- wall thickness, if you have thin walls like 0.5 to 2mm, the chances of delamination are higher.
- object design. If your object has large wall areas and 90 degree sharp corners there are stresses in the material due to shrinking unevenly. You can design your parts with holes to relieve the stresses, and use chamfered or rounded corners.
- If the corners don't lift during printing or after cooling, it means it's sticking very well to the bed. The consequence is that the stresses needs to go somewhere and often result in delamination. Printing in an enclosure to keep the temperature more constant may help. With pla one often uses a part cooling fan. If the ambient temperature is too low the part cools too quickly and too much.
- using a heated bed helps. For pla 40-60 degrees is usually working well.
- As said above print temperature has an effect on adhesion. Normally the higher it is the better it is. At some point it gets too high and causes stringing, blobs during retractions and expands/shrinks more.
- often when the print is just finished, it's not yet delaminated, but during cooling, too rapidly, it cracks. Let it cool slowly in an enclosure, or put a few sheets of paper kitchen towels over it to insulate it. It's also possible to use some end gcode to lower the bed temperature in steps of 10 degrees until 30 degrees is reached, waiting between each step a couple of minutes.
- if the extruder isn't extruding evenly the chance you get weak parts increases. If one layer prints thinner than the next you need to find out why the extruder isn't running consistently. Check motor current, the filament path isn't blocked or binding, the hobbed bolt should be propetly aligned and the idler should apply the proper pressure, not to much, not yoo little.
- a very level bed helps with first layer adhesion and also the next layers as they may be squeezed or too far apart.

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Kind regards
Imqqmi

NFAN CoreXY printer:
[reprap.org]

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soccerox817
I have a Prusa i3 Rework that I am building for a school project. I have been able to get it to print; however, my layer adhesion is suffering. There are gaps between the layers. How do I get the layers to bond better? Here are my printing settings: Black PLA at 220 C for the hotend and 65 C for the bed. I'm printing directly on glass. I'm not quite sure what speed I'm printing at. I didn't change any of Slicer's presets. Thank you for any help you can offer- Jacob

Before you proceed, check to make sure the tempature your printer is "saying" it is using, are the actual tempature a using a meter. 60 on the heatbed will cause your prints to warp...

But also, maybe check your z steps to make sure it isn't moving up to far too fast.