Fighting with the first layer

Recently, three events happened in a row that is leaving me with the problem of getting the first layer of my 3D prints to stick. The PLA filament that I was using ran out. An update to OctoPrint went sour, resulting in a rebuild. Lastly, I updated the version Cura I am using. 

I have tried several ways to get the print to stick. First was flipping the glass bed over. I have gone through the bed leveling process (both manual and automatic) several times. According to Bed Visualizer, I am close. In Cura, I have tweaked the 'Initial Layer Height' to 0.1 and the 'Build Plate Temperature' to 65C. The results I have gotten so far are either the filament doesn't stick or after a few layers, the edges start to curl and pull away from the bed. 

My next set of changes involved using a glue stick and switching from a skirt to a brim. I was able to get a 'CHEP Calibration Cube' to print. The print popped right of the bed. Closer inspection of the print revealed that the first layer is under extruded and the edges of the print pulled away from the bed. The top of the print (last layer) looks like the nozzle dig in a little (over extrusion).

I compared the latest print to prints from the previous roll of filament. The first layer on the previous filament is much thicker.

Possible Options

• Make sure the bed is level
• Good prints start with a level bed. 
• Did this 4 times earlier in the day
• Reduce the print speed for the first layer
• It idea behind the slower print speed is to give the filament time to flow out of the nozzle into place and harden.
• the current setting is 25 mm/s. This seems reasonable speed. I will skip with option
• Increase the height of the first layer 
• From what I have read, increasing the initial layer height can reduce the backpressure on the filament which should let the filament flow out a little easier.
• Increase the extrusion amount for the first layer
• This should force a bit more filament out. There is a possibility of the print suffering from an elephant's foot. It could also increase the backpressure on the filament.
• Increase the extruder temperature
• A little more heat could allow the filament to flow a little easier. 
• Check the filament diameter setting
• The filament size is 1.75 in the settings. 
• Checked the nozzle diameter at the same time. 

Setting up for the next test print

Reprinting the CHEP Calibration Cube. Changed the initial layer height from 0.1 to 0.12. Changed printing temperature from 195C to 200C. Used the glue stick on the bed. 

Results

The print stuck to the bed a lot better. The first layer doesn't have as many defects and imperfections. I can clearly see a space between each line the makes up the first layer. This looks under extruded.

It seems this filament like the 200C. 

Setting up for the next test print

Reprinting the CHEP Calibration Cube. Changed the initial layer height from 0.12 to 0.18. Used the glue stick again. 

Results

There is even less under extrusion with the first layer. 

Setting up for the next test print

This time, I going to print the CHEP Calibration Cube, one of the tolerance tests from Makers Muse, and a few models of my own design (drop ceiling clip). Changed the initial layer height from 0.18 to 0.20. Changed from brim to skirt. Used the glue stick on the bed.

Results

I canceled the print just as the 3rd layer was starting. One of the models was not sticking to the bed. The first layer is under extruded. 

Setting up for the next test print

Just printing the CHEP Calibration Cube. Changed the initial layer flow from 100% to 102%. Wiped the bed down with Isopropyl Alcohol. Used the glue stick.

Results

The print was really stuck down. I have to use a putty knife to get the print free. The individual lines that make up the first layer are a little fatter and there is still a bit of space between the lines. 

Wrap up

This turned out to be a good learning experience. The lesson of a 'level bed is the starting point' was re-enforced. I learned that the distance between the 'bed and the nozzle', 'how fast the material flows out of the nozzle', and 'type of bed surface' all impact each other.