When you’re experiencing difficulties with prints sticking to the build plate, there could be a few things going on. It could either mean that the first layer just doesn’t stick well enough or that the prints gets loose due to “warping” of the plastic. Warping basically happens because of the material properties. Plastics have the tendency to shrink when cooling down fast (some plastics more than others), which could eventually lead to loose and deformed corners of your print. You will especially notice this behaviour when printing ABS, which has a relatively big shrinkage.
This page describes some tips on improving the adhesion of your print to the build plate.
Heated bed temperature
When you have an Ultimaker with heated bed it’s important to use the correct bed temperature. This way you ensure the first layer of the print doesn’t cool too much, due to which it could shrink a lot. For PLA we for example recommend a temperature of 60°C, while ABS needs a temperature of 90°C. The default settings on the Ultimaker and in Cura should be fine for this, but with some materials it could help to slightly increase the bed temperature. Also the fact that the print head fans are usually turned off during the first layer helps in this case.
For printing it is very important that the first layer is nicely squished into the glass plate and sticks well. If the distance between the nozzle and build plate is too big, your print won’t stick properly to the glass plate. On the other hand, if the nozzle is too close to the build plate it can prevent the filament from extruding from the nozzle. In both cases this will lead to a bad first layer, which might eventually lead to adhesion problems. Therefore we advise to always re-level the build plate when experiencing issues with the first layer of your print.
For good adhesion it is important that the print surface is smooth and clean. There should be no traces of oil or grease (e.g. from your fingers) on the build plate, as that will only lead to worse adhesion.
If you have an Ultimaker that uses blue tape as a print surface, make sure to replace it once in a while. Tape can damage and thus cause an uneven print surface.
For Ultimakers with a heated bed it’s advised to either keep the glass plate completely clean or to apply glue to it. If you print with PLA it’s not always necessary to use glue (only with bigger objects), so mostly a clean glass plate will work. Ensure there are no greasy fingerprints on the glass plate though. If you print with a material like ABS or CPE you always need to apply glue to the glass plate. You can simply put a thin layer of glue on the glass plate and (optionally) distribute it with a damp cloth. Furthermore, you need to make sure that the glass plate is regularly cleaned. Excessive glue can be removed with some water (and soap) and to completely get rid of greasy fingerprints you could use some alcohol.
A nice feature in Cura to help preventing warping is called “Brim”. It will place a single layer thick flat area around your object, thus creating a bigger adhesion surface. This way the warping on your print will be minimized. After printing the brim can easily be removed from the print.
To use the brim you must go to the Full settings in Cura. You can find it under “Support” > “Platform adhesion type”.
In The Classroom
This is a professional development resource to allow you to learn some of the tips and tricks for producing better 3D prints in the classroom. This is not a general classroom resource, however it may be useful at the stage when students are working independently to print their own designs. If students are having problems with prints coming unstuck, share this link with them so that they can learn tips of how to address the issue.